体育活动而非久坐时间会影响青少年后期的骨骼强度。

Physical activity, but not sedentary time, influences bone strength in late adolescence.

机构信息

School of Health Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Malaysia.

Department of Family Practice, Faculty of Medicine, University of British Columbia, Vancouver, Canada.

出版信息

Arch Osteoporos. 2018 Mar 20;13(1):31. doi: 10.1007/s11657-018-0441-9.

DOI:10.1007/s11657-018-0441-9

PMID:29556801

Abstract

UNLABELLED

Physical activity is essential for optimal bone strength accrual, but we know little about interactions between physical activity, sedentary time, and bone outcomes in older adolescents. Physical activity (by accelerometer and self-report) positively predicted bone strength and the distal and midshaft tibia in 15-year-old boys and girls. Lean body mass mediated the relationship between physical activity and bone strength in adolescents.

PURPOSE

To examine the influence of physical activity (PA) and sedentary time on bone strength, structure, and density in older adolescents.

METHODS

We used peripheral quantitative computed tomography to estimate bone strength at the distal tibia (8% site; bone strength index, BSI) and tibial midshaft (50% site; polar strength strain index, SSI) in adolescent boys (n = 86; 15.3 ± 0.4 years) and girls (n = 106; 15.3 ± 0.4 years). Using accelerometers (GT1M, Actigraph), we measured moderate-to-vigorous PA (MVPA), vigorous PA (VPA), and sedentary time in addition to self-reported MVPA (MVPA) and impact PA (ImpactPA). We examined relations between PA and sedentary time and bone outcomes, adjusting for ethnicity, maturity, tibial length, and total body lean mass.

RESULTS

At the distal tibia, MVPA and VPA positively predicted BSI (explained 6-7% of the variance, p < 0.05). After adjusting for lean mass, only VPA explained residual variance in BSI. At the tibial midshaft, MVPA, but not VPA, positively predicted SSI (explained 3% of the variance, p = 0.01). Lean mass attenuated this association. MVPA and ImpactPA also positively predicted BSI and SSI (explained 2-4% of the variance, p < 0.05), but only ImpactPA explained residual variance in BSI after accounting for lean mass. Sedentary time did not independently predict bone strength at either site.

CONCLUSION

Greater tibial bone strength in active adolescents is mediated, in part, by lean mass. Despite spending most of their day in sedentary pursuits, adolescents' bone strength was not negatively influenced by sedentary time.

摘要

非标记

身体活动对于获得最佳骨强度至关重要，但我们对青少年时期身体活动、久坐时间和骨骼结果之间的相互作用知之甚少。身体活动（通过加速度计和自我报告）正向预测了 15 岁男孩和女孩的骨强度和远端胫骨及中段胫骨。在青少年中，瘦体重介导了身体活动与骨强度之间的关系。

目的

研究身体活动（PA）和久坐时间对青少年晚期骨骼强度、结构和密度的影响。

方法

我们使用外周定量计算机断层扫描技术来估计青少年男孩（n=86；15.3±0.4 岁）和女孩（n=106；15.3±0.4 岁）的远端胫骨（8%处；骨强度指数，BSI）和胫骨中段（50%处；极强度应变指数，SSI）的骨强度。使用加速度计（GT1M，Actigraph），我们测量了中等到剧烈的 PA（MVPA）、剧烈的 PA（VPA）和久坐时间，以及自我报告的 MVPA（MVPA）和冲击 PA（ImpactPA）。我们在调整了种族、成熟度、胫骨长度和全身瘦体重后，研究了 PA 和久坐时间与骨骼结果之间的关系。

结果

在远端胫骨处，MVPA 和 VPA 正向预测 BSI（解释了 6-7%的方差，p<0.05）。调整瘦体重后，只有 VPA 解释了 BSI 的剩余方差。在胫骨中段处，MVPA 但不是 VPA 正向预测 SSI（解释了 3%的方差，p=0.01）。瘦体重减弱了这种关联。MVPA 和 ImpactPA 也正向预测 BSI 和 SSI（解释了 2-4%的方差，p<0.05），但仅 ImpactPA 在考虑瘦体重后解释了 BSI 的剩余方差。久坐时间在两个部位都不能独立预测骨强度。