Correlation Between Energy Balance And Body Composition Changes After 12 Weeks Of Exercise In Overweight Premenopausal Women

Abstract

The national recommendation for the amount of physical activity (PA) needed to achieve and maintain a healthy body weight is 13-26 kcal/kg/day. The wide range in exercise dose is due partly to exercise studies that inadequately assessed energy balance components that either complement or compensate for experimental increases in exercise energy expenditure (ExEE). PURPOSE:To determine the energy balance correlates of changes in body composition resulting from a 12-week endurance training intervention. METHODS:Twenty-four previously sedentary, overweight women were randomly assigned to a high (26 kcal/kg/day) or low dose (13 kcal/kg/day) of endurance exercise. Twelve-week changes in weight, body composition estimates from air displacement plethysmography, waist circumference from anthropometry, 19-hour post-exercise resting energy expenditure (REE) from indirect calorimetry, energy intake (EI) from 7-day food diaries, and spontaneous physical activity (SPA) from 7-days of wearing piezoelectric pedometers were assessed. RESULTS:There were no mean differences between high- and low-dose exercise groups in the 12-week changes in average body weight (p=0.79), fat mass (p=0.44), fat-free mass (p=0.52), waist circumference (p=0.24), EI (p=0.94), or SPA (p=0.29). When groups were combined, there were significant 12-week changes in waist circumference (-1.0 ± 1.9 cm, p=0.02) and fat-free mass (+0.6 ± 1.2 kg, p=0.03). In addition, average ExEE was inversely correlated with changes in fat mass (r=-0.50, p=0.01) and waist circumference (r=-0.56, p<0.01), and positively correlated with post-exercise REE (r=0.42, p=0.04). Moreover, post-exercise REE was inversely correlated with changes in fat mass (r-0. 47, p=0.02) and waist circumference (r=-0.60, p<0.01), and positively correlated with changes in fat-free mass (r=0.47, p=0.02) and SPA (r=0.44, p=0.03). CONCLUSIONS:Exercise-related reductions in fat mass and waist circumference are correlated with higher ExEE and post-exercise REE. Furthermore, higher post-exercise REE is also correlated with greater exercise-related increases in fat-free mass and SPA. Our findings suggest that national physical activity recommendations aimed at improving body composition focus on effective ways to sustain increases in ExEE.