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CrossFit Exercise to Improve Glucose Control for Overweight and Obese Adults

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02185872
Recruitment Status : Completed
First Posted : July 10, 2014
Last Update Posted : March 31, 2015
Information provided by (Responsible Party):
Katie M. Heinrich, Kansas State University

Brief Summary:

The purpose of this study was to examine the differences in glucose control, fitness, and body composition between a standard aerobic and resistance exercise training program and a shorter-duration, high-intensity CrossFit training program in overweight and obese physically inactive adults.


  1. Both groups would improve glucose control, with the CrossFit group improving significantly more than the aerobic and resistance training group.
  2. Both groups would improve fitness, with the CrossFit group improving significantly more than the aerobic and resistance training group.
  3. Both groups would demonstrate decreases in body fat percentage and fat mass and increases in lean body mass, with the CrossFit group improving significantly more than the aerobic and resistance training group.

Condition or disease Intervention/treatment Phase
Hyperglycemia Other: High-Intensity Functional Training Other: Aerobic and Resistance Training Not Applicable

Detailed Description:
Overweight or obese participants will take part in an 8-week exercise intervention after clearance from a doctor, that is expected to improve glucose control, fitness (Eurofit and peak aerobic capacity), and body composition (body fat percentage, fat mass, and lean body mass). After stratification by age and body mass index, participants will be randomized to either a standard aerobic and resistance training exercise program or a relatively higher intensity, shorter duration CrossFit exercise program.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 23 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: The Influence of a CrossFit Exercise Program on Glucose Control in Overweight and Obese Individuals
Study Start Date : February 2012
Actual Primary Completion Date : May 2012
Actual Study Completion Date : May 2012

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: Aerobic and Resistance Training
Participants completed 24 exercise sessions based on current guidelines. Aerobic exercise (50 min) was performed on machines every session and resistance training (20 min) was performed on machines two sessions per week. Aerobic intensity was prescribed at 40-50% of heart rate reserve (HRR) Weeks 1-4 and 50-60% HRR Weeks 5-8. Resistance training was supervised by an ACE certified personal trainer. One-repetition maximums (1-RM) were assessed Week 1 (i.e., seated bicep curl, military press, seated lat pulldown, seated leg extension, triceps pulldown, bench press, reverse leg curl, seated leg press). For Weeks 2-3 participants completed, 3 sets of 15 reps at 50% 1-RM; Weeks 4-5, 3 sets of 12 reps at 60% 1-RM; Weeks 6-7, 3 sets of 10 reps at 70% 1-RM; Week 8, 3 sets of 8 reps at 75% 1-RM. Three sets of 15 unweighted crunches were completed each day. One minute of rest was taken between each set and each exercise.
Other: Aerobic and Resistance Training
The protocol was based upon current guidelines of 150 minutes moderate-intensity aerobic activity and 2 days of muscle strengthening per week.

Experimental: High-intensity functional training
Participants completed a total of 24 sessions that were pre-programmed and led by a certified instructor (CrossFit Level 2), which lasted up to 60 minutes in duration. The first two class periods were structured as an introduction to common movements used in high-intensity functional training (HIFT; e.g., squats, deadlift, press, jerks, barbell, dumbbell, and medicine ball cleans, pullups, kettlebell swings, among others). No scheduled workouts were given on days 1 and 2. Beginning on day 3 each HIFT class consisted of 10-15 minutes of stretching and warmup, 10-20 minutes of instruction and practicing techniques and movements, and 5-30 minutes for the workout of the day, performed at vigorous intensity, relative to each person's ability and fitness level. All weights and movements were individually prescribed and recorded for each participant.
Other: High-Intensity Functional Training
Participants were instructed to work as hard as they could while maintaining safe technique and proper form to achieve as many reps or rounds as possible in the prescribed time frame. As HIFT participants became accustomed to specific movements, less time was dedicated to practicing movements and technique.
Other Name: CrossFit

Primary Outcome Measures :
  1. Change from baseline in glucose control. [ Time Frame: Baseline, Week 10 ]
    Fasting plasma glucose levels were taken after an overnight fast of at least 8 hours. An oral glucose tolerance test was conducted after ingestion of a 75g oral dextrose solution with finger sticks at 30, 45, and 60 minutes from time 0. The following equation was used to calculate glucose area under the curve which was the metric utilized to ascertain changes in glucose control: [(Time 45 - Time 30) * ½ (OGTT 30 + OGTT 45)] + [(Time 60 - Time 45) * ½ (OGTT 60 + OGTT 45)]

Secondary Outcome Measures :
  1. Change from baseline in peak aerobic capacity [ Time Frame: Baseline, Week 10 ]
    Modified Balke protocol

  2. Change from baseline in sit and reach [ Time Frame: Baseline, Week 10 ]
    Eurofit protocol for sit and reach distance using flex tester box

  3. Change from baseline in standing broad jump [ Time Frame: Baseline, Week 10 ]
    Eurofit protocol

  4. Change from baseline in vertical jump [ Time Frame: Baseline, Week 10 ]
    Eurofit protocol

  5. Change from baseline in pushups [ Time Frame: Baseline, Week 10 ]
    Eurofit protocol; completed on feet or knees

  6. Change from baseline in situps [ Time Frame: Baseline, Week 10 ]
    Eurofit protocol

  7. Change from baseline in 40 meter dash [ Time Frame: Baseline, Week 10 ]
    A handheld stopwatch was used to record time from the command "Go" until the participant crossed the line at 40 meters

  8. Change from baseline in stork balance test [ Time Frame: Baseline, Week 10 ]
  9. Change from baseline in body composition [ Time Frame: Baseline, Week 12 ]
    Dual X-ray absorptiometry scan was used to assess body fat percentage, lean body mass, and fat mass.

Other Outcome Measures:
  1. Time spent completing daily workouts [ Time Frame: 24 exercise sessions over 8 weeks ]
    Time spent to complete each assigned daily workout was individually recorded for each participant

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • body mass index (BMI) of 25 - < 40, physically inactive (i.e., not participating in any structured exercise programs for the past 2 months and not exceeding 30 total minutes of physical activity per week)

Exclusion Criteria:

  • current smoker, pregnant, taking blood glucose altering medications, heart disease, type 1 or 2 diabetes mellitus, total cholesterol 200 mg/dL or higher

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02185872

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United States, Kansas
Kansas State University
Manhattan, Kansas, United States, 66506
Sponsors and Collaborators
Kansas State University
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Principal Investigator: Katie M Heinrich, PhD Kansas State University
Study Director: Pratik Patel, MS, RD Kansas State University
Publications of Results:
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Responsible Party: Katie M. Heinrich, Assistant Professor, Kansas State University Identifier: NCT02185872    
Other Study ID Numbers: #6058
First Posted: July 10, 2014    Key Record Dates
Last Update Posted: March 31, 2015
Last Verified: March 2015
Keywords provided by Katie M. Heinrich, Kansas State University:
Physical Fitness
Body Composition, Beneficial
Additional relevant MeSH terms:
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Body Weight
Glucose Metabolism Disorders
Metabolic Diseases