Changes in body composition after a 12-wk aerobic exercise program in obese boys.

UNLABELLED: Previous studies have shown that vigorous aerobic training programs for obese children result in minimal weight changes, and concluded that they may not be beneficial. Weight change alone may not detect important beneficial changes in body composition associated with vigorous training in these children. Fifteen obese boys (aged 9-12 yr, body mass index (BMI) 31.8+/-6.5, average percent body fat (%BF) 41+/-4.2) underwent a supervised aerobic and resistance training program (12 wk, 2 days/wk for 30 min/session), to investigate the effects on weight and body composition. After the 3-month training period, weight loss averaged only 1.5+/-1.0 kg (not significant), but total body fat decreased by 4.1+/-1.8 kg (p<0.05) and fat-free mass (FFM) increased by 2.6+/-1.1 kg (p<0.05) based on hydrostatic weighing. As a result, %BF fell by 10% (p<0.01). There was a 5.8+/-2.8 mL/kg/min (p<0.05) increase in peak volume of oxygen uptake (VO(2)), along with a 248+/-120 kcal/d (p<0.05) increase in resting energy expenditure (REE). Activity questionnaires showed a significant increase in high intensity recreational activities (6.5+/-1.5 vs 3.5+/-0.5 h physical activity/wk; p<0.01) in the home and a significant decrease in low intensity activities (7+/-2.0 vs 12+/-3.5 h TV viewing/wk; p<0.01).
CONCLUSIONS: Vigorous supervised aerobic training in obese boys has beneficial effects on body composition, fitness and leisure time activities that are not apparent by measurement of changes in body weight alone.