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Trial record 1 of 1 for:    NCT 00729378
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Jump-In: Building Better Bones

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ClinicalTrials.gov Identifier: NCT00729378
Recruitment Status : Completed
First Posted : August 7, 2008
Results First Posted : December 8, 2017
Last Update Posted : December 8, 2017
Sponsor:
Information provided by (Responsible Party):
Scott Going, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

Study Type Interventional
Study Design Allocation: Randomized;   Intervention Model: Parallel Assignment;   Masking: None (Open Label);   Primary Purpose: Basic Science
Condition Adolescent Development
Intervention Other: Skeletal loading
Enrollment 509
Recruitment Details Recruitment was performed for three years (2007-2009) in a total of 16 elementary and middle schools (9 intervention and 7 control) in two Tucson, Arizona area school districts. Recruitment consisted of attending back to school days and holding recruitment assemblies before or after school.
Pre-assignment Details Intervention and control schools designated prior to recruiting. Schools were selected based on size, demographics, and student flow from elementary to middle school to prevent contamination. 739 participants completed informed consent process (agreed to participate); only 509 scheduled measurement appointments and completed study measurements.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description

Subjects in the exercise intervention arm performed activities designed to provide skeletal loading: impact activities, 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Subjects in the control arm did not take part in intervention exercises. Physical activity performed by these subjects was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).
Period Title: Baseline
Started 430 309
Completed 292 217
Not Completed 138 92
Reason Not Completed
Did not complete study measurements             72             33
Withdrawal by Subject             66             59
Period Title: 12-months
Started 292 217
Completed 192 152
Not Completed 100 65
Reason Not Completed
Lost to Follow-up             100             65
Period Title: 24-months
Started 192 152
Completed 120 101
Not Completed 72 51
Reason Not Completed
Lost to Follow-up             72             51
Period Title: 36-months
Started 120 101
Completed 105 95
Not Completed 15 6
Reason Not Completed
Lost to Follow-up             15             6
Arm/Group Title Exercise Intervention Control Total
Hide Arm/Group Description

Subjects in the exercise intervention arm performed activities designed to provide skeletal loading: impact activities, 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Subjects in the control arm did not take part in intervention exercises. Physical activity performed by these subjects was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ). Total of all reporting groups
Overall Number of Baseline Participants 292 217 509
Hide Baseline Analysis Population Description
[Not Specified]
Age, Continuous  
Mean (Standard Deviation)
Unit of measure:  Years
Number Analyzed 292 participants 217 participants 509 participants
10.6  (1.1) 10.7  (1.0) 10.7  (1.1)
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 292 participants 217 participants 509 participants
Female
292
 100.0%
217
 100.0%
509
 100.0%
Male
0
   0.0%
0
   0.0%
0
   0.0%
Ethnicity (NIH/OMB)  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 292 participants 217 participants 509 participants
Hispanic or Latino
67
  22.9%
50
  23.0%
117
  23.0%
Not Hispanic or Latino
225
  77.1%
167
  77.0%
392
  77.0%
Unknown or Not Reported
0
   0.0%
0
   0.0%
0
   0.0%
Race (NIH/OMB)  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 292 participants 217 participants 509 participants
American Indian or Alaska Native
1
   0.3%
2
   0.9%
3
   0.6%
Asian
20
   6.8%
11
   5.1%
31
   6.1%
Native Hawaiian or Other Pacific Islander
2
   0.7%
1
   0.5%
3
   0.6%
Black or African American
11
   3.8%
3
   1.4%
14
   2.8%
White
254
  87.0%
196
  90.3%
450
  88.4%
More than one race
2
   0.7%
0
   0.0%
2
   0.4%
Unknown or Not Reported
2
   0.7%
4
   1.8%
6
   1.2%
Region of Enrollment  
Measure Type: Count of Participants
Unit of measure:  Participants
United States Number Analyzed 292 participants 217 participants 509 participants
292
 100.0%
217
 100.0%
509
 100.0%
1.Primary Outcome
Title Baseline Total Volumetric Bone Density at the Femur 4% Site
Hide Description Baseline (initial) measurement of total volumetric bone density at the femur 4% site. Measurement made by peripheral quantitative computed tomography (pQCT) at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
277.25  (33.83) 270.79  (32.97)
2.Primary Outcome
Title Baseline Volumetric Bone Density of Trabecular Bone at the Femur 4% Site
Hide Description Baseline (initial) measurement of volumetric bone density of trabecular bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
239.32  (32.2) 232.34  (31.56)
3.Primary Outcome
Title Baseline Volumetric Bone Density of Cortical Bone at the Femur 4% Site
Hide Description Baseline (initial) measurement of volumetric bone density of Cortical bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
273.80  (31.23) 267.89  (30.75)
4.Primary Outcome
Title Baseline Trabecular Bone Area at the Femur 4% Site
Hide Description Baseline (initial) measurement of trabecular bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
1039.55  (220.17) 1053.15  (227.32)
5.Primary Outcome
Title Baseline Cortical Bone Area at the Femur 4% Site
Hide Description Baseline (initial) measurement of cortical bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
1335.56  (274.22) 1348.65  (284.24)
6.Primary Outcome
Title Baseline Periosteal Circumference at the Femur 4% Site
Hide Description Baseline (initial) measurement of periosteal circumference at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
124.91  (12.42) 125.63  (12.50)
7.Primary Outcome
Title Baseline Bone Strength Index at the Femur 4% Site
Hide Description Baseline (initial) measurement of bone strength index (BSI) at the femur 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: mm^4
96.77  (28.00) 93.52  (27.39)
8.Primary Outcome
Title Baseline Total Volumetric Bone Density at the Femur 20% Site
Hide Description Baseline (initial) measurement of total volumetric bone density at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
489.70  (63.98) 478.72  (60.59)
9.Primary Outcome
Title Baseline Volumetric Bone Density of Trabecular Bone at the Femur 20% Site
Hide Description Baseline (initial) measurement of volumetric bone density of trabecular bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
163.81  (39.43) 153.11  (36.77)
10.Primary Outcome
Title Baseline Volumetric Bone Density of Cortical Bone at the Femur 20% Site
Hide Description Baseline (initial) measurement of volumetric bone density of Cortical bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
1046.01  (22.27) 1045.20  (23.07)
11.Primary Outcome
Title Baseline Periosteal Circumference at the Femur 20% Site
Hide Description Baseline (initial) measurement of periosteal circumference at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
77.43  (8.56) 77.78  (8.66)
12.Primary Outcome
Title Baseline Cortical Thickness at the Femur 20% Site
Hide Description Baseline (initial) measurement of cortical thickness at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
2.52  (.37) 2.50  (.35)
13.Primary Outcome
Title Baseline Stress-Strain Index at the Femur 20% Site
Hide Description Baseline (initial) measurement of stress-strain index at the femur 20% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: mm^3
1340.19  (404.78) 1344.66  (399.31)
14.Primary Outcome
Title Baseline Volumetric Bone Density of Trabecular Bone at the Tibia 4% Site
Hide Description Baseline (initial) measurement of volumetric bone density of trabecular bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
224.03  (27.58) 219.74  (25.56)
15.Primary Outcome
Title Baseline Total Volumetric Bone Density at the Tibia 4% Site
Hide Description Baseline (initial) measurement of total volumetric bone density at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
297.27  (37.02) 291.62  (33.17)
16.Primary Outcome
Title Baseline Volumetric Bone Density of Cortical Bone at the Tibia 4% Site
Hide Description Baseline (initial) measurement of volumetric bone density of cortical bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
297.40  (35.63) 291.93  (31.92)
17.Primary Outcome
Title Baseline Trabecular Bone Area at the Tibia 4% Site
Hide Description Baseline (initial) measurement of trabecular bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
467.73  (100.86) 475.80  (108.85)
18.Primary Outcome
Title Baseline Cortical Bone Area at the Tibia 4% Site
Hide Description Baseline (initial) measurement of cortical bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
617.19  (117.67) 625.57  (127.11)
19.Primary Outcome
Title Baseline Periosteal Circumference at the Tibia 4% Site
Hide Description Baseline (initial) measurement of periosteal circumference at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
85.86  (8.36) 86.43  (8.82)
20.Primary Outcome
Title Baseline Bone Strength Index at the Tibia 4% Site
Hide Description Baseline (initial) measurement of bone strength index (BSI) at the tibia 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: mm^4
52.45  (15.15) 51.03  (13.63)
21.Primary Outcome
Title Baseline Total Volumetric Bone Density at the Tibia 50% Site
Hide Description Baseline (initial) measurement of total volumetric bone density at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
745.69  (59.54) 736.33  (58.07)
22.Primary Outcome
Title Baseline Volumetric Bone Density of Trabecular Bone at the Tibia 50% Site
Hide Description Baseline (initial) measurement of volumetric bone density of trabecular bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
137.39  (26.83) 131.63  (26.97)
23.Primary Outcome
Title Baseline Volumetric Bone Density of Cortical Bone at the Tibia 50% Site
Hide Description Baseline (initial) measurement of volumetric bone density of cortical bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
1070.32  (32.88) 1070.95  (31.93)
24.Primary Outcome
Title Baseline Periosteal Circumference at the Tibia 50% Site
Hide Description Baseline (initial) measurement of periosteal circumference at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
61.98  (5.43) 62.33  (5.83)
25.Primary Outcome
Title Baseline Cortical Thickness at the Tibia 50% Site
Hide Description Baseline (initial) measurement of cortical thickness at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
4.05  (.58) 4.00  (.54)
26.Primary Outcome
Title Baseline Stress-Strain Index at the Tibia 50% Site
Hide Description Baseline (initial) measurement of stress-strain index at the tibia 50% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: mm^3
1004.97  (272.40) 1023.74  (297.42)
27.Primary Outcome
Title Baseline Total Volumetric Bone Density at the Tibia 66% Site
Hide Description Baseline (initial) measurement of total volumetric bone density at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
566.04  (63.11) 552.71  (61.05)
28.Primary Outcome
Title Baseline Volumetric Bone Density of Trabecular Bone at the Tibia 66% Site
Hide Description Baseline (initial) measurement of volumetric bone density of trabecular bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
159.04  (30.48) 152.34  (28.73)
29.Primary Outcome
Title Baseline Volumetric Bone Density of Cortical Bone at the Tibia 66% Site
Hide Description Baseline (initial) measurement of volumetric bone density of cortical bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
1029.42  (32.92) 1026.07  (31.38)
30.Primary Outcome
Title Baseline Periosteal Circumference at the Tibia 66% Site
Hide Description Baseline (initial) measurement of periosteal circumference at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
71.55  (6.53) 72.34  (7.25)
31.Primary Outcome
Title Baseline Cortical Thickness at the Tibia 66% Site
Hide Description Baseline (initial) measurement of cortical thickness at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
3.06  (.49) 3.02  (.46)
32.Primary Outcome
Title Baseline Stress-Strain Index at the Tibia 66% Site
Hide Description Baseline (initial) measurement of strength-strain index at the tibia 66% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline time point (N = 503; Age = 10.6 +/- 1.1 yrs; Height = 144.5 +/- 9.7 cm; Weight = 39.2 +/- 10.5 kg).
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 286 217
Mean (Standard Deviation)
Unit of Measure: mm^3
1167.94  (331.61) 1187.31  (353.09)
33.Primary Outcome
Title 12-month Change in Total Volumetric Bone Density the Femur 4% Site
Hide Description Baseline to 12-month change in total volumetric bone density at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
3.10  (15.36) 2.83  (12.32)
34.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Trabecular Bone at the Femur 4% Site
Hide Description Baseline to 12-month change in volumetric bone density of trabecular bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
3.37  (15.23) 5.89  (12.94)
35.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Cortical Bone at the Femur 4% Site
Hide Description Baseline to 12-month change in volumetric bone density of cortical bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
2.14  (14.47) 1.68  (11.47)
36.Primary Outcome
Title 12-month Change in Trabecular Bone Area at the Femur 4% Site
Hide Description Baseline to 12-month change in trabecular bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
104.16  (111.80) 144.97  (96.38)
37.Primary Outcome
Title 12-month Change in Cortical Bone Area at the Femur 4% Site
Hide Description Baseline to 12-month change in cortical bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
140.00  (131.17) 185.50  (119.42)
38.Primary Outcome
Title 12-month Change in Periosteal Circumference at the Femur 4% Site
Hide Description Baseline to 12-month change in periosteal circumference at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
6.17  (5.80) 8.09  (4.84)
39.Primary Outcome
Title 12-month Change in Bone Strength Index at the Femur 4% Site
Hide Description Baseline to 12-month change in bone strength index (BSI) at the femur 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^4
12.84  (12.67) 15.03  (14.19)
40.Primary Outcome
Title 12-month Change in Total Volumetric Bone Density at the Femur 20% Site
Hide Description Baseline to 12-month change in total volumetric bone density at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
2.40  (22.38) -2.46  (18.74)
41.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Trabecular Bone at the Femur 20% Site
Hide Description Baseline to 12-month change in volumetric bone density of trabecular bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
7.12  (12.98) 5.77  (12.38)
42.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Cortical Bone at the Femur 20% Site
Hide Description Baseline to 12-month change in volumetric bone density of cortical bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
6.87  (20.02) 4.39  (19.38)
43.Primary Outcome
Title 12-month Change in Thickness of Cortical Bone at the Femur 20% Site
Hide Description Baseline to 12-month change in thickness of cortical bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.11  (.17) .11  (.15)
44.Primary Outcome
Title 12-month Change in Periosteal Circumference at the Femur 20% Site
Hide Description Baseline to 12-month change in periosteal circumference at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
4.89  (2.21) 5.65  (2.20)
45.Primary Outcome
Title 12-month Change in Stress-Strain Index at the Femur 20% Site
Hide Description Baseline to 12-month change in strength-strain index at the femur 20% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
261.94  (137.73) 297.43  (145.31)
46.Primary Outcome
Title 12-month Change in Total Volumetric Bone Density at the Tibia 4% Site
Hide Description Baseline to 12-month change in total volumetric bone density at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
9.87  (17.29) 10.34  (19.34)
47.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 4% Site
Hide Description Baseline to 12-month change in volumetric bone density of trabecular bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
2.84  (10.22) 2.36  (9.33)
48.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 4% Site
Hide Description Baseline to 12-month change in volumetric bone density of cortical bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
9.69  (16.76) 10.10  (18.73)
49.Primary Outcome
Title 12-month Change in Trabecular Bone Area at the Tibia 4% Site
Hide Description Baseline to 12-month change in trabecular bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
29.87  (52.91) 24.65  (50.00)
50.Primary Outcome
Title 12-month Change in Cortical Bone Area at the Tibia 4% Site
Hide Description Baseline to 12-month change in cortical bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
44.85  (54.14) 39.53  (49.12)
51.Primary Outcome
Title 12-month Change in Periosteal Circumference at the Tibia 4% Site
Hide Description Baseline to 12-month change in periosteal circumference at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
3.17  (3.70) 2.77  (3.44)
52.Primary Outcome
Title 12-month Change in Bone Strength Index at the Tibia 4% Site
Hide Description Baseline to 12-month change in bone strength index (BSI) at the tibia 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^4
7.84  (5.39) 7.46  (5.53)
53.Primary Outcome
Title 12-month Change in Total Volumetric Bone Density at the Tibia 50% Site
Hide Description Baseline to 12-month change in total volumetric bone density at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
17.98  (22.27) 17.76  (22.02)
54.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 50% Site
Hide Description Baseline to 12-month change in volumetric bone density of trabecular bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
-2.74  (13.55) -3.16  (15.63)
55.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 50% Site
Hide Description Baseline to 12-month change in volumetric bone density of cortical bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
14.34  (22.23) 11.16  (18.91)
56.Primary Outcome
Title 12-month Change in Periosteal Circumference at the Tibia 50% Site
Hide Description Baseline to 12-month change in periosteal circumference at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
2.98  (1.33) 3.11  (1.09)
57.Primary Outcome
Title 12-month Change in Cortical Thickness at the Tibia 50% Site
Hide Description Baseline to 12-month change in cortical thickness at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.29  (.20) .31  (.20)
58.Primary Outcome
Title 12-month Change in Stress-Strain Index at the Tibia 50% Site
Hide Description Baseline to 12-month change in strength-strain index at the tibia 50% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
171.82  (68.00) 185.36  (79.04)
59.Primary Outcome
Title 12-month Change in Total Volumetric Bone Density at the Tibia 66% Site
Hide Description Baseline to 12-month change in total volumetric bone density at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
7.00  (32.41) 9.58  (29.98)
60.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 66% Site
Hide Description Baseline to 12-month change in volumetric bone density of trabecular bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate.Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
3.40  (13.49) 2.08  (14.64)
61.Primary Outcome
Title 12-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 66% Site
Hide Description Baseline to 12-month change in volumetric bone density of cortical bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 9
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
11.63  (24.00) 12.69  (21.32)
62.Primary Outcome
Title 12-month Change in Periosteal Circumference at the Tibia 66% Site
Hide Description Baseline to 12-month change in periosteal circumference at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
3.69  (2.35) 3.79  (2.06)
63.Primary Outcome
Title 12-month Change in Cortical Thickness at the Tibia 66% Site
Hide Description Baseline to 12-month change in cortical thickness at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.17  (.21) .18  (.22)
64.Primary Outcome
Title 12-month Change in Stress-Strain Index at the Tibia 66% Site
Hide Description Baseline to 12-month change in strength-strain index at the tibia 66% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 12-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
214.93  (96.58) 228.46  (103.48)
65.Primary Outcome
Title 24-month in Change in Total Volumetric Bone Density the Femur 4% Site
Hide Description Baseline to 24-month change in total volumetric bone density at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units mg/ccm.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
13.70  (22.89) 13.47  (19.09)
66.Primary Outcome
Title 24-month in Change in Volumetric Bone Density of Trabecular Bone at the Femur 4% Site
Hide Description Baseline to 24-month change in volumetric bone density of trabecular bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
8.03  (19.34) 8.23  (16.35)
67.Primary Outcome
Title 24-month in Change in Volumetric Bone Density of Cortical Bone at the Femur 4% Site
Hide Description Baseline to 24-month change in volumetric bone density of cortical bone at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Group Control Group
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
10.67  (21.83) 10.78  (17.95)
68.Primary Outcome
Title 24-month Change in Trabecular Bone Area at the Femur 4% Site
Hide Description Baseline to 24-month change in trabecular bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

.

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
160.89  (158.53) 178.04  (146.00)
69.Primary Outcome
Title 24-month Change in Cortical Bone Area at the Femur 4% Site
Hide Description Baseline to 24-month change in cortical bone area at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
237.12  (178.61) 255.67  (165.23)
70.Primary Outcome
Title 24-month Change in Periosteal Circumference at the Femur 4% Site
Hide Description Baseline to 24-month change in periosteal circumference at the femur 4% site . Measurement made by pQCT at a distance of 4% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
10.08  (7.73) 10.72  (6.88)
71.Primary Outcome
Title 24-month Change in Bone Strength Index at the Femur 4% Site
Hide Description Baseline to 24-month change in bone strength index (BSI) at the femur 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^4
28.08  (17.51) 27.81  (17.76)
72.Primary Outcome
Title 24-month Change in Total Volumetric Bone Density at the Femur 20% Site
Hide Description Baseline to 24-month change in total volumetric bone density at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
14.88  (31.73) 15.36  (28.47)
73.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Trabecular Bone at the Femur 20% Site
Hide Description Baseline to 24-month change in volumetric bone density of trabecular bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
11.83  (17.20) 9.04  (13.87)
74.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Cortical Bone at the Femur 20% Site
Hide Description Baseline to 24-month change in volumetric bone density of cortical bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
21.56  (29.46) 22.26  (29.62)
75.Primary Outcome
Title 24-month Change in Thickness of Cortical Bone at the Femur 20% Site
Hide Description Baseline to 24-month change in thickness of cortical bone at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.27  (.22) .31  (.21)
76.Primary Outcome
Title 24-month Change in Periosteal Circumference at the Femur 20% Site
Hide Description Baseline to 24-month change in periosteal circumference at the femur 20% site . Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
8.25  (3.38) 9.29  (3.08)
77.Primary Outcome
Title 24-month Change in Stress-Strain Index at the Femur 20% Site
Hide Description Baseline to 24-month change in strength-strain index at the femur 20% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 20% of total femur length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
504.12  (202.34) 582.69  (202.42)
78.Primary Outcome
Title 24-month Change in Total Volumetric Bone Density at the Tibia 4% Site
Hide Description Baseline to 24-month change in total volumetric bone density at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
28.22  (30.58) 26.76  (29.35)
79.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 4% Site
Hide Description Baseline to 24-month change in volumetric bone density of trabecular bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
7.37  (13.97) 7.23  (17.18)
80.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 4% Site
Hide Description Baseline to 24-month change in volumetric bone density of cortical bone at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
27.29  (29.54) 25.94  (28.46)
81.Primary Outcome
Title 24-month Change in Trabecular Bone Area at the Tibia 4% Site
Hide Description Baseline to 24-month change in trabecular bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
34.81  (70.70) 35.83  (75.98)
82.Primary Outcome
Title 24-month Change in Cortical Bone Area at the Tibia 4% Site
Hide Description Baseline to 24-month change in cortical bone area at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: square millimeters (mm^2).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters squared (mm^2)
65.50  (69.84) 66.42  (73.94)
83.Primary Outcome
Title 24-month Change in Periosteal Circumference at the Tibia 4% Site
Hide Description Baseline to 24-month change in periosteal circumference at the tibia 4% site . Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
4.64  (4.82) 4.65  (5.15)
84.Primary Outcome
Title 24-month Change in Bone Strength Index at the Tibia 4% Site
Hide Description Baseline to 24-month change in bone strength index (BSI) at the tibia 4% site. Bone Strength Index (BSI) is a measurement of the resistance to compression forces at the epiphyses of long bones. Measurement made by pQCT at a distance of 4% of total tibia length from the distal growth plate. Measurement units: mm^4.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^4
17.28  (9.35) 16.86  (10.14)
85.Primary Outcome
Title 24-month Change in Total Volumetric Bone Density at the Tibia 50% Site
Hide Description Baseline to 24-month change in total volumetric bone density at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
37.26  (29.74) 39.83  (32.94)
86.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 50% Site
Hide Description Baseline to 24-month change in volumetric bone density of trabecular bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
-3.51  (15.84) -4.00  (14.16)
87.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 50% Site
Hide Description Baseline to 24-month change in volumetric bone density of cortical bone at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
33.70  (27.35) 31.06  (26.75)
88.Primary Outcome
Title 24-month Change in Periosteal Circumference at the Tibia 50% Site
Hide Description Baseline to 24-month measurement of periosteal circumference at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
5.26  (2.12) 5.27  (1.63)
89.Primary Outcome
Title 24-month Change in Cortical Thickness at the Tibia 50% Site
Hide Description Baseline to 24-month change in cortical thickness at the tibia 50% site . Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.51  (.28) .53  (.28)
90.Primary Outcome
Title 24-month Change in Stress-Strain Index at the Tibia 50% Site
Hide Description Baseline to 24-month change in strength-strain index at the tibia 50% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 50% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
322.78  (114.10) 336.49  (112.47)
91.Primary Outcome
Title 24-month Change in Total Volumetric Bone Density at the Tibia 66% Site
Hide Description Baseline to 24-month change in total volumetric bone density at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
17.83  (38.18) 19.26  (41.46)
92.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Trabecular Bone at the Tibia 66% Site
Hide Description Baseline to 24-month change in volumetric bone density of trabecular bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
4.48  (14.20) 1.69  (16.02)
93.Primary Outcome
Title 24-month Change in Volumetric Bone Density of Cortical Bone at the Tibia 66% Site
Hide Description Baseline to 24-month change in volumetric bone density of cortical bone at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: milligrams per cubic centimeter (mg/ccm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: milligrams per cubic centimeter (mg/ccm)
28.96  (28.71) 31.06  (28.49)
94.Primary Outcome
Title 24-month Change in Periosteal Circumference at the Tibia 66% Site
Hide Description Baseline to 24-month change in periosteal circumference at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
6.75  (3.07) 6.82  (3.06)
95.Primary Outcome
Title 24-month Change in Cortical Thickness at the Tibia 66% Site
Hide Description Baseline to 24-month change in cortical thickness at the tibia 66% site . Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: millimeters (mm).
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: millimeters (mm)
.32  (.27) .32  (.31)
96.Primary Outcome
Title 24-month Change in Stress-Strain Index at the Tibia 66% Site
Hide Description Baseline to 24-month change in strength-strain index at the tibia 66% site. Stress-strain index (also called strength-strain index and stress-strength index in the literature) is a measure of the resistance to torsional and bending forces at diaphyseal sites of long bones. Measurement made by pQCT at a distance of 66% of total tibia length from the distal growth plate. Measurement units: mm^3.
Time Frame Baseline to 24-months
Hide Outcome Measure Data
Hide Analysis Population Description
Population consists of all participants that had complete measurements at the baseline, 12-month and 24-month time points (N=207). At 12-months: Age=11.8 +/- 1.0 yrs; Height=153.3 +/- 9.9 cm; Weight=44.0 +/- 9.3 kg. At 24-months: Age=12.8 +/- 1.0 yrs; Height=158.8 +/- 9.1 cm; Weight=50.0 +/- 10.7 kg.
Arm/Group Title Exercise Intervention Control
Hide Arm/Group Description:

Participants randomized to the exercise intervention group performed activities designed to provide skeletal loading: impact activities 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities were introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Physical activity performed by these subjects (in addition to intervention activities) was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire PYPAQ).

Participants randomized to the control arm did not perform intervention activities. Physical activity was objectively assessed by pedometer (7-day wear period) and further assessed by a validated past year physical activity questionnaire (PYPAQ).
Overall Number of Participants Analyzed 109 98
Mean (Standard Deviation)
Unit of Measure: mm^3
421.49  (172.67) 435.13  (164.78)
Time Frame Since the time frame was based on a "school year", adverse event data were collected twice a year (at the end of each school semester) for up to 5 years (the duration of the study).
Adverse Event Reporting Description [Not Specified]
 
Arm/Group Title Exercise Intervention Arm Control Arm
Hide Arm/Group Description

Implementation of intervention program designed to provide skeletal loading through high impact activities.

Skeletal loading: impact activities, 3 times per week, increasing the number of jumps (up to 40) and increasing height (from 6 inches to 24 inches per repetition) over the initial 8-weeks (2 months). New activities will be introduced approximately every 2-3 months in order to continually stress the skeleton over 2 years.

Participants in this arm will not take part in intervention exercises. All activities performed by subjects in control arm will be assessed by physical activity questionnaire and use of pedometer.
All-Cause Mortality
Exercise Intervention Arm Control Arm
Affected / at Risk (%) Affected / at Risk (%)
Total   --/--   --/-- 
Hide Serious Adverse Events
Exercise Intervention Arm Control Arm
Affected / at Risk (%) Affected / at Risk (%)
Total   0/292 (0.00%)   0/217 (0.00%) 
Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 0%
Exercise Intervention Arm Control Arm
Affected / at Risk (%) Affected / at Risk (%)
Total   0/292 (0.00%)   0/217 (0.00%) 
Certain Agreements
All Principal Investigators ARE employed by the organization sponsoring the study.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Dr. Scott Going, Ph.D.
Organization: University of Arizona
Phone: 520-626-3432
EMail: going@u.arizona.edu
Layout table for additonal information
Responsible Party: Scott Going, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
ClinicalTrials.gov Identifier: NCT00729378    
Other Study ID Numbers: HD050775
First Submitted: August 5, 2008
First Posted: August 7, 2008
Results First Submitted: April 24, 2017
Results First Posted: December 8, 2017
Last Update Posted: December 8, 2017