Physical Activity and Basal Metabolic Rate in Postmenopausal Women

Aging and Basal Metabolic Rate in Postmenopausal Women: Effects of Long-Term and Short-Term Physical Activity

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 Overview

• Status: Completed
• Conditions: Postmenopausal Metabolic Health
• Intervention / Treatment: Behavioral: Resistance and aerobic exercise

• Study Type: Interventional
• Enrollment (Actual): 49
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • La Jolla, California, United States, 92037
      • La Jolla YMCA
    • La Jolla, California, United States, 92093-0623
      • UCSD Human Exercise Physiology Laboratory
    • San Diego, California, United States, 92093-0990
      • UCSD General Clinical Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 40 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• naturally postmenopausal (i.e. non-surgically)/> 1 year since last menstruation
• FSH > 30 mIU/ml
• estradiol-17β < 25 pg/ml

Exclusion Criteria:

• smoker, abuser of alcohol/other drugs
• hypo- or hyperthyroid (serum TSH < 0.3 or > 5.5 microU/ml, respectively)
• underweight or severely obese (BMI < 18.5 or > 35 kg/m2, respectively)
• weight instability within the past six months (±> 5% of body weight)
• hormone replacement therapy within the past six months
• history of metabolic, respiratory or cardiovascular disease
• high blood pressure
• contraindication for maximal aerobic testing as determined by PAR-Q questionnaire and physician's examination

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Training; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in basal metabolic rate	Basal metabolic rate is the energy expended at rest and under fasting conditions.	baseline, 5, 10 and 16 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fat-free mass		baseline, 5, 10 and 16 weeks
Change in maximal aerobic capacity	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.	baseline, 16 weeks

Collaborators and Investigators

• Sponsor: University of California, San Diego
• Collaborators: National Center for Research Resources (NCRR); Sigma Xi; Wenner Gren
• Investigators: Principal Investigator: Andrew W Froehle, PhD, University of California, San Diego

Publications and helpful links

General Publications

• Froehle AW, Ngo HT, Hopkins SR, Natarajan L, Schoeninger MJ. 2010. Relationship between physical activity, body composition and basal metabolic rate in postmenopausal women. Am J Hum Biol 22:252-253. [meeting abstract]
• Froehle AW, Ngo HT, Natarajan L, Schoeninger MJ, Hopkins SR. 2011. Short-term exercise does not elevate basal metabolic rate (BMR) in postmenopausal women in the absence of increased fat free mass (FFM). Am J Hum Biol 23:259. [meeting abstract]

Study record dates

Study Major Dates

• Study Start: January 1, 2008
• Primary Completion (Actual): August 1, 2010
• Study Completion (Actual): August 1, 2010

Study Registration Dates

• First Submitted: March 5, 2012
• First Submitted That Met QC Criteria: March 9, 2012
• First Posted (Estimated): March 12, 2012

Study Record Updates

• Last Update Posted (Actual): November 29, 2023
• Last Update Submitted That Met QC Criteria: November 27, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Keywords: physical activity; menopause; metabolic syndrome; resting energy expenditure; basal metabolic rate
• Other Study ID Numbers: UCSD GCRC 1910/6766; 5M01RR000827-35 (U.S. NIH Grant/Contract)