FITNESS AND ENERGY-EXPENDITURE AFTER STRENGTH TRAINING IN OBESE PREPUBERTAL GIRLS

Purpose: The purpose of this study was to determine the effects of a s chool-based, low-volume strength training program on energy expenditur e, strength, and physical fitness in obese prepubertal girls. Methods: A longitudinal, 5-month strength training exercise program was undert aken by healthy, obese (>95th percentile weight-for-height, N = 11) gi rls age 7-10 yr, The following were measured: strength by the one-repe tition maximum test; fitness ((V) over dot O-2peak) by a treadmill exe rcise test; resting metabolic rate (RMR), 24-h sedentary energy expend iture (SEE)I and sleeping metabolic rate (SMR) by room respiration cal orimetry; and total energy expenditure (TEE) by the doubly labeled wat er method. Physical activity energy expenditure (AEE) was calculated a s TEE - (RMR + 0.1TEE) and physical activity level (PAL) as TEE/RMR. An age-matched, nonoverweight control group was measured for (V) over dot O-2peak and RMR over the same time period. Results: Strength incre ased by 19.6 and 20.0% in the upper and lower body (P < 0.01), respect ively. (V) over dot O-2peak (mL min(-1)) increased in both groups over time (P < 0.05), but not when covaried for fat-free mass (FFM) or wei ght. After adjusting for FFM or weight, RMR did not change, but SMR an d 24-h SEE decreased significantly in the exercise group. There were n o changes in nonprotein respiratory quotient or substrate oxidation. N o changes in TEE, AEE, and PAL occurred, either unadjusted or adjusted for FFM or weight. Conclusion: This long-term, school-based, low-volu me strength training program favorably increases strength in obese pre pubertal girls but does not increase their daily energy expenditure.