Swiss Tropical and Public Health Institute, 4053 Basel, Switzerland.
Bone. 2013 Jul;55(1):16-22. doi: 10.1016/j.bone.2013.03.005. Epub 2013 Mar 17.
As an important modifiable lifestyle factor in osteoporosis prevention, physical activity has been shown to positively influence bone mass accrual during growth. We have previously shown that a nine month general school based physical activity intervention increased bone mineral content (BMC) and density (aBMD) in primary school children. From a public health perspective, a major key issue is whether these effects persist during adolescence. We therefore measured BMC and aBMD three years after cessation of the intervention to investigate whether the beneficial short-term effects persisted.
All children from 28 randomly selected first and fifth grade classes (intervention group (INT): 16 classes, n=297; control group (CON): 12 classes, n=205) who had participated in KISS (Kinder-und Jugendsportstudie) were contacted three years after cessation of the intervention program. The intervention included daily physical education with daily impact loading activities over nine months. Measurements included anthropometry, vigorous physical activity (VPA) by accelerometers, and BMC/aBMD for total body, femoral neck, total hip, and lumbar spine by dual-energy X-ray absorptiometry (DXA). Sex- and age-adjusted Z-scores of BMC or aBMD at follow-up were regressed on intervention (1 vs. 0), the respective Z-score at baseline, gender, follow-up height and weight, pubertal stage at follow-up, previous and current VPA, adjusting for clustering within schools.
377 of 502 (75%) children participated in baseline DXA measurements and of those, 214 (57%) participated to follow-up. At follow-up INT showed significantly higher Z-scores of BMC at total body (adjusted group difference: 0.157 units (0.031-0.283); p=0.015), femoral neck (0.205 (0.007-0.402); p=0.042) and at total hip (0.195 (0.036 to 0.353); p=0.016) and higher Z-scores of aBMD for total body (0.167 (0.016 to 0.317); p=0.030) compared to CON, representing 6-8% higher values for children in the INT. No differences could be found for the remaining bone parameters. For the subpopulation with baseline VPA (n=163), effect sizes became stronger after baseline VPA adjustment. After adjustment for baseline and current VPA (n=101), intervention effects were no longer significant, while effect sizes remained the same as without adjustment for VPA.
Beneficial effects on BMC of a nine month general physical activity intervention appeared to persist over three years. Part of the maintained effects may be explained by current physical activity.
作为预防骨质疏松症的重要可改变生活方式因素，身体活动已被证明可积极影响生长过程中的骨量积累。我们之前已经表明，为期九个月的普通学校基础身体活动干预可增加小学生的骨矿物质含量（BMC）和密度（aBMD）。从公共卫生的角度来看，一个主要的关键问题是这些影响是否在青春期持续存在。因此，我们在干预停止后三年测量 BMC 和 aBMD，以调查短期的有益效果是否持续存在。
所有参与 KISS（儿童和青少年运动研究）的 28 个随机选择的一年级和五年级班级（干预组（INT）：16 个班级，n=297；对照组（CON）：12 个班级，n=205）的儿童均在干预计划停止三年后联系。干预包括九个月的日常体育课和日常冲击负荷活动。测量包括人体测量学、加速度计测量的剧烈体力活动（VPA）以及双能 X 射线吸收法（DXA）测量的全身、股骨颈、全髋和腰椎的 BMC/aBMD。随访时的 BMC 或 aBMD 的性别和年龄调整 Z 分数回归于干预（1 比 0）、基线时的相应 Z 分数、性别、随访时的身高和体重、随访时的青春期阶段、以前和当前的 VPA，同时考虑到学校内的聚类。
在基线 DXA 测量中，502 名儿童中有 377 名（75%）参与，其中 214 名（57%）参与了随访。在随访时，INT 显示全身 BMC 的 Z 分数明显更高（调整后的组间差异：0.157 个单位（0.031-0.283）；p=0.015）、股骨颈（0.205（0.007-0.402）；p=0.042）和全髋（0.195（0.036 至 0.353）；p=0.016）以及全身 aBMD 的 Z 分数更高（0.167（0.016 至 0.317）；p=0.030），与 CON 相比，INT 中的儿童的数值高出 6-8%。对于其余的骨参数，没有发现差异。对于基线 VPA 有数据的亚组（n=163），在调整基线 VPA 后，效应大小增强。在调整基线和当前 VPA 后（n=101），干预效果不再显著，而在不调整 VPA 的情况下，效应大小保持不变。
为期九个月的普通身体活动干预对 BMC 的有益影响似乎在三年后仍持续存在。部分维持的效果可能可以用当前的体力活动来解释。
