Physical Activity and Basal Metabolic Rate in Postmenopausal Women
The primary purpose of this study is to expand research on the effects of physical activity on basal metabolic rate (BMR) in healthy postmenopausal women, and to further compare the effects of long-term habitual exercise to the results of a shorter-term (16 weeks) training program. The investigators will measure BMR by indirect calorimetry and normalize it across subjects for body size (fat free mass) and level of aerobic fitness (VO2MAX). Two groups will be compared: an intervention group (no previous participation in regular exercise, newly enrolled in this study's 16 week training program), and a long-term athlete group (have engaged in at least 5 hours of exercise per week for the past 10 years or longer). A secondary aim is to generate an equation for the prediction of BMR from fat free mass in physically active postmenopausal women, to be applied to hypotheses in biological anthropology. The investigators expect to find at baseline that, controlling for fat free mass and VO2MAX, the long-term group will have significantly higher BMR than the intervention group. At 16 weeks the investigators expect no change in BMR for the long-term group, while BMR will have increased in the intervention group. At the same time, the investigators expect to find that after completing the training regimen, the intervention group will have BMR similar to that of the long-term athletes.
|Study Design:||Allocation: Non-Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Basic Science
|Official Title:||Aging and Basal Metabolic Rate in Postmenopausal Women: Effects of Long-Term and Short-Term Physical Activity|
- Change in basal metabolic rate [ Time Frame: baseline, 5, 10 and 16 weeks ] [ Designated as safety issue: No ]Basal metabolic rate is the energy expended at rest and under fasting conditions.
- Change in fat-free mass [ Time Frame: baseline, 5, 10 and 16 weeks ] [ Designated as safety issue: No ]
- Change in maximal aerobic capacity [ Time Frame: baseline, 16 weeks ] [ Designated as safety issue: No ]The maximal oxygen consumption achieved during a graded exercise test to exhaustion. Equipment: electronically-braked cycle ergometer. Participants were screened for CVD risk prior to testing by a physician. Lead II EKG was monitored during testing, and each test was overseen by a physician.
|Study Start Date:||January 2008|
|Study Completion Date:||August 2010|
|Primary Completion Date:||August 2010 (Final data collection date for primary outcome measure)|
Sedentary women who exercised <2 hours per week and who had never engaged in a regular exercise program were enrolled in an exercise training intervention, following baseline measurements. See intervention below.
Behavioral: Resistance and aerobic exercise
Following baseline measurements, sedentary women were enrolled in a 16-week exercise training program at the YMCA in La Jolla, CA. Exercise occurred 3 times per week, for 1.5 hours each time. Exercise consisted of stretching, 20 minutes of aerobic exercise on elliptical machines, and 3 sets of 10-12 repetitions to failure for each of ten weight lifting exercises: abdominal crunch, arm curl, arm extension, chest press, lat pull-down, leg curl, leg extension, leg press, seated row, and trunk extension. Women started at 65-75% of 1-repetition-maximum, and resistance was increased as necessary to maintain the number of sets and reps and to continue to work to failure. Exercise was monitored by a TechnoGym electronic key system, and trainers instructed and supervised subjects in the gym.
No Intervention: Active
Postmenopausal women who exercised >5 hours per week and had been doing so for at least the past 10 years. These women were asked to maintain their normal activity habits for the duration of the study.
|United States, California|
|UCSD Human Exercise Physiology Laboratory|
|La Jolla, California, United States, 92093-0623|
|La Jolla YMCA|
|La Jolla, California, United States, 92037|
|UCSD General Clinical Research Center|
|San Diego, California, United States, 92093-0990|
|Principal Investigator:||Andrew W Froehle, PhD||University of California, San Diego|