Department of Bioengineering, Northeastern University, Boston, MA.
Department of Psychology, Northeastern University, Boston, MA.
Med Sci Sports Exerc. 2020 Feb;52(2):434-440. doi: 10.1249/MSS.0000000000002148.
Obesity 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.
青少年肥胖会对多个系统的健康造成影响。本研究旨在确定青春期前超重/肥胖儿童的骨骼是否会对 9 个月的身体活动干预做出反应，从而像健康体重儿童那样增加骨密度。
参与者包括超重/肥胖（BMI＞85%）和健康体重（15%＜BMI＜85%）的青春期前儿童（8-9 岁）。身体活动组的参与者每天在课后参加 9 个月的身体活动课程。等待对照组没有接受干预。两组均包括超重/肥胖儿童和健康体重对照组。在身体活动组和对照组中，在 9 个月的试验开始和结束时，使用双能 X 线吸收法（DXA）评估全身骨矿物质含量、面积和骨矿物质表观密度（BMAD）。
超重/肥胖的青春期前儿童的 BMAD 高于健康体重儿童（脊柱、腿部和全身 P＜0.001）。然而，超重/肥胖儿童的密度/体重（BMAD/瘦体重）低于健康体重儿童，表明超重/肥胖儿童的骨骼密度可能不足以充分补偿体重带来的过度负荷。在整个身体和腿部，健康体重儿童的 BMAD 在 9 个月内的变化大于超重/肥胖儿童，但在腰椎则不然。身体活动导致骨骼密度的部位特异性增加，腿部的影响大于腰椎，但运动对健康体重和超重/肥胖组的影响没有显著差异。
与健康体重儿童相比，超重/肥胖儿童在 9 个月内的 BMAD 变化较小，单位瘦体重的 BMAD 较低，这可能表明骨量积累的速度较慢，这可能对肥胖/超重儿童在骨骼生长期间的骨骼健康产生影响。
