Regional fat changes induced by localized muscle endurance resistance training

The purpose of this study was to examine the effects of a localized muscle endurance resistance training program on total body and regional tissue composition. Seven men and 4 women (aged 23 ± 1 years) were trained with their nondominant leg during 12 weeks, 3 sessions per week. Each session consisted of 1 set of 960-1,200 repetitions (leg press exercise), at 10-30% 1 repetition maximum. Before and after training, body mass, bone mass, bone mineral density (BMD), lean mass, fat mass, and fat percentage were determined by dual-emission x-ray absorptiometry. Energy intakes were registered using a food recall questionnaire. At the whole-body level, body mass, bone mass, BMD, lean mass, or body fat percentage were not significantly changed. However, body fat mass significantly decreased by 5.1% (preexercise: 13.5 ± 6.3 kg; postexercise: 12.8 ± 5.4 kg, p < 0.05). No significant changes in bone mass, lean mass, fat mass, or fat percentage were observed in both the control and trained leg. A significant (p < 0.05) decrease in fat mass was observed in the upper extremities and trunk (10.2 and 6.9%, respectively, p < 0.05). The reduction of fat mass in the upper extremities and trunk was significantly greater (p < 0.05) than the fat mass change observed in the trained leg but not in the control leg. No significant changes were observed in energy intake pre- and postexercise intervention (2,646 ± 444 kcal·d-1 and 2,677 ± 617 kcal·d-1, respectively). In conclusion, the training program was effective in reducing fat mass, but this reduction was not achieved in the trained body segment. The present results expand the limited knowledge available about the plastic heterogeneity of regional body tissues when a localized resistance training program is applied.