Effect of physical training and its cessation on percent fat and bone density of children with obesity

Objective: We determined the effect of 4-month periods of physical training (PT) and detraining on percent fat (percent fat) and bone density of child ren with obesity. Research Methods and Procedures: Subjects were 79 7- to 11-year-old childre n with obesity; 34 were white, 44 were black, and 1 was Asian, 26 were male and 53 were female. They were randomly assigned to two groups: group 1 en gaged in PT for the first 4 months, while group 2 engaged in PT during the second 4 months. Body composition was measured with dual energy absorptiome try, and diet was measured with 4 days of recall for each 4-month period. P T was offered 5 days/week for 40 minutes/session, heart rate monitors were worn, and no dietary information was given; mean attendance was 80%, and me an heart rate per session was 157 bpm. Results: Group by time interactions across the three time-points (from anal ysis of variance) were significant fur percent fat (p=<0.001) and bone dens ity (p=0.045). Both groups declined in percent fat during the periods of PT , by an average of 1.6 %fat units; in the 3 months after cessation of PT, g roup 1 increased by 1.3 %fat. In both groups, bone density increased more d uring periods of PT (0.025 g/cm(2)) than during periods of no PT (0.010 g/c m(2)). No significant PT vs. no-PT differences were found for dietary intak e of energy, macronutrients, or calcium. Discussion: This study suggests that regular exercise, without dietary inte rvention, can enhance the body composition of children with obesity.