during adolescence has multisystem health consequences. The objective of this work was to determine whether preadolescent overweight/obese children’s bones respond to a 9-month physical activity
intervention by increasing bone density
similar to healthy weight children.
Participants included overweight/obese (BMI > 85%) and healthy weight (15% < BMI < 85%) preadolescents (8–9 yr old). Participants in the physical activity
group participated in a 9-month physical activity
curriculum every day after school. The wait list control group received no intervention. Both groups had overweight/obese children and healthy weight controls. Whole-body bone mineral content, area, and bone mineral apparent density (BMAD) were assessed using dual x-ray absorptiometry) at the beginning and end of the 9-month trial in the physical activity
and control group.
Overweight/obese preadolescent children had higher BMAD than healthy weight children (P
< 0.001 for spine, leg, and whole body). However, the density/weight (BMAD/lean mass) was lower in overweight/obese children than that in healthy weight children, indicating that the density of bones in overweight/obese children may not compensate sufficiently for the excessive load due to weight. The change in BMAD over 9 months was greater in healthy weight children than overweight/obese children in the whole body and leg, but not the lumbar spine. Physical activity
caused a site-specific increase in bone density
, affecting the legs more than the lumbar spine, but there was no significant difference in the effect of exercise between the healthy weight and the overweight/obese group.
The smaller change in BMAD over the 9 months and lower BMAD per unit lean mass in overweight/obese compared with healthy weight children may indicate a slower rate of bone mass accrual, which may have implications for bone health during skeletal growth in obese/overweight children.