Submitted to: Obesity
Publication Type: Abstract only
Publication Acceptance Date: 8/1/2007
Publication Date: 9/1/2007
Citation: Miller, F., Jackson, A., Sailors, M., McFarlin, B., Bray, M. 2007. Change in body composition following a 15-week, heart rate monitored aerobic exercise program: The TIGER study [abstract]. Obesity. 15(Suppl.):325-P. Interpretive Summary:
Technical Abstract: The joint goals of the Training Interventions and Genetics of Exercise Response (TIGER) study are to introduce sedentary college-age individuals to regular exercise and identify genetic factors that influence physiologic response to aerobic exercise training. The purpose of the study was to examine the body composition changes produced with a 15-week heart rate regulated aerobic exercise program. The sample included 797 participants (41% male and 59% female), age 17 to 30 y. The race/ethnic composition was; 29% non-Hispanic White: 23% Hispanic; 28% African-American; 5% Asian-Indian; 10% Asian; and 5% other. Aerobic exercise frequency was 3 days per week for a duration of 30 minutes per session at a prescribed intensity of 65-85% max heart rate. Polar heart rate monitors were used to regulate exercise intensity. Random-intercept, linear mixed model (LMM) regression evaluated changes in body composition. The fixed effect variables were gender, time (0 and 15 weeks), gender by time interaction. The dependent variables were DXA and percent body fat (%fat) and body mass index (BMI) assessed at baseline and at 15 weeks. The LLM random component was multiple time points. The analyses showed that the fixed effects of gender, time, and gender by time interaction for both DXA %fat and BMI were statistically significant (p < 0.01). The LMM analyses documented that the exercise program significantly decreased BMI and DXA %fat of both men and women, but the men's changes were larger than those found for the women. The LMM modeled 15-week BMI and DXA %fat changes were: women, -0.47 kg/m2 and -0.59%; and men, 0.73 kg/m2 and -1.05%. Post hoc within gender LMM analyses showed there was no significant time by race/ethnic group interactions. The TIGER 15-week exercise program consisting of 30 m of aerobic exercise at 65-85% max HR 3 days per week produced significant decreases in BMI and DXA %fat. These findings can be generalized to the major race/ethnic groups studied.