Macdonald H M, Kontulainen S A, Petit M A, Beck T J, Khan K M, McKay H A
Department of Orthopaedics, University of British Columbia, #302 2647 Willow St, Vancouver, BC, Canada, V5Z 3P1.
Osteoporos Int. 2008 Oct;19(10):1445-56. doi: 10.1007/s00198-008-0589-z. Epub 2008 Mar 21.
The effects of physical activity on bone strength acquisition during growth are not well understood. In our cluster randomized trial, we found that participation in a novel school-based physical activity program enhanced bone strength acquisition and bone mass accrual by 2-5% at the femoral neck in girls; however, these benefits depended on teacher compliance with intervention delivery. Our intervention also enhanced bone mass accrual by 2-4% at the lumbar spine and total body in boys.
We investigated the effects of a novel school-based physical activity program on femoral neck (FN) bone strength and mass in children aged 9-11 yrs.
We used hip structure analysis to compare 16-month changes in FN bone strength, geometry and bone mineral content (BMC) between 293 children who participated in Action Schools! BC (AS! BC) and 117 controls. We assessed proximal femur (PF), lumbar spine (LS) and total body (TB) BMC using DXA. We compared change in bone outcomes between groups using linear regression accounting for the random school effect and select covariates.
Change in FN strength (section modulus, Z), cross-sectional area (CSA), subperiosteal width and BMC was similar between control and intervention boys, but intervention boys had greater gains in BMC at the LS (+2.7%, p = 0.05) and TB (+1.7%, p = 0.03) than controls. For girls, change in FN-Z tended to be greater (+3.5%, p = 0.1) for intervention girls than controls. The difference in change increased to 5.4% (p = 0.05) in a per-protocol analysis that included girls whose teachers reported 80% compliance.
AS! BC benefits bone strength and mass in school-aged children; however, our findings highlight the importance of accounting for teacher compliance in classroom-based physical activity interventions.
体育活动对生长过程中骨强度获得的影响尚未得到充分理解。在我们的整群随机试验中，我们发现参与一项新型的校内体育活动计划可使女孩股骨颈的骨强度获得和骨量积累提高2%至5%；然而，这些益处取决于教师对干预措施实施的依从性。我们的干预措施还使男孩腰椎和全身的骨量积累提高了2%至4%。
我们研究了一项新型的校内体育活动计划对9至11岁儿童股骨颈（FN）骨强度和骨量的影响。
我们使用髋部结构分析比较了293名参与“行动学校！不列颠哥伦比亚”（AS! BC）计划的儿童与117名对照组儿童在16个月内FN骨强度、几何形状和骨矿物质含量（BMC）的变化。我们使用双能X线吸收法（DXA）评估股骨近端（PF）、腰椎（LS）和全身（TB）的BMC。我们使用线性回归分析，并考虑随机学校效应和选定的协变量，比较两组之间骨指标的变化。
对照组和干预组男孩之间，FN强度（截面模量，Z）、横截面积（CSA）、骨膜下宽度和BMC的变化相似，但干预组男孩在LS处的BMC增加幅度更大（+2.7%，p = 0.05），在TB处的增加幅度也大于对照组（+1.7%，p = 0.03）。对于女孩，干预组女孩的FN-Z变化倾向于大于对照组（+3.5%，p = 0.1）。在一项符合方案分析中，该差异增加到5.4%（p = 0.05），该分析纳入了教师报告依从性达80%的女孩。
AS! BC计划对学龄儿童的骨强度和骨量有益；然而，我们的研究结果凸显了在基于课堂的体育活动干预中考虑教师依从性的重要性。
