Condition
Conditions
Brief summary
The overall goal is to determine whether any energy expenditure compensation in response to 16 weeks of aerobic exercise at a higher-dose is greater compared to a lower-dose intervention in older women, and to begin to investigate underlying physiological mechanisms that influence energy expenditure changes in older women.
Detailed description
The overall goal is to determine whether any energy expenditure compensation in response to 16 weeks of aerobic exercise at a higher-dose is greater compared to a lower-dose intervention in older women, and to begin to investigate underlying physiological mechanisms that influence energy expenditure changes in older women. Changes in all components of energy expenditure, as well as concentrations of plasma leptin and serum free T3, in response to the two different exercise programs (14 and 8 kcal/kg body weight weekly, 60-65% VO2max, 4 days/wk) will be compared in older, non-obese women (60-75 yrs, BMI=18-30 kg/m2). Specific Aim 1: To determine whether differential changes in total daily energy expenditure and its components occur in older women in response to two exercise programs of different doses. State-of-the-art methods will be used (total daily energy expenditure by doubly labeled water; non-exercise activity thermogenesis using Physical Activity Monitoring System; resting metabolic rate and thermic effect of food via indirect calorimetry). Primary Hypothesis: Due to a greater decline in NEAT, women will exhibit a smaller increase in total daily energy expenditure in response to the higher-dose, compared to the lower-dose, exercise program, despite greater increases in resting metabolic rate and thermic effect of food. Specific Aim 2: To explore whether differential changes occur in plasma leptin and serum free triiodo-L-thyronine (free T3) concentrations in older women in response to 16-week aerobic exercise programs of two different doses. We hypothesize that in response to the higher-dose exercise program, women will exhibit larger decreases in plasma leptin and serum free T3 concentrations, compared to the lower-dose exercise program. We will also determine whether women exhibit greater improvements in plasma lipids, insulin sensitivity (using homeostasis model assessment, HOMA, score), blood pressure, and aerobic fitness in response to the higher-dose, compared to the lower-dose, exercise program.
Interventions
BEHAVIORALLow Dosage
Exercise dose of 8kcal/kg/week
BEHAVIORALHigh Dosage
Exercise dose of 14kcal/kg/week
Sponsors
University of South Carolina
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
SUPPORTIVE_CARE
Masking
NONE
Eligibility
Sex/Gender
FEMALE
Age
60 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
* BMI 18-30 * Sedentary (exercising less than 20 minutes no more than 3 times per week) * Non-smoking * Weight stable (+/- 5%) over past 3 months
Exclusion criteria
* Self-reported cardiovascular disease * Additional self-reported medical conditions * Medications known to affect metabolism * Excess caffeine use * Self-reported contradictions according to ACSM * Unwillingness to provide informed consent
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Change from baseline total daily energy expenditure and its components (resting metabolic rate, thermic effect of food, non-exercise activity thermogenesis)in 4 months | Baseline (pre-intervention); 4 months (post-intervention) |
Secondary
| Measure | Time frame |
|---|---|
| Change from baseline plasma leptin and serum free triiodo-L-thyronine (free T3) concentrations in 4 months | Baseline (pre-intervention); 4 month (post-intervention) |
Countries
United States
Outcome results
None listed