Department of Health and Human Physiology, The University of Iowa, Iowa City, IA.
Med Sci Sports Exerc. 2020 Nov;52(11):2331-2341. doi: 10.1249/MSS.0000000000002380.
High-impact physical activity is associated with bone health, but higher volumes of lower-intensity activity may also be important. The aims of this study were to: 1) investigate the relative importance of volume and intensity of physical activity accumulated during late adolescence for bone health at age 23 yr; and 2) illustrate interpretation of the results.
This is a secondary analysis of data from the Iowa Bone Development Study, a longitudinal study of bone health from childhood through to young adulthood. The volume (average acceleration) and intensity distribution (intensity gradient) of activity at age 17, 19, 21, and 23 yr were calculated from raw acceleration ActiGraph data and averaged across ages. Hip areal bone mineral density (aBMD), total body bone mineral content (BMC), spine aBMD, and hip structural geometry (dual-energy X-ray absorptiometry, Hologic QDR4500A) were assessed at age 23 yr. Valid data, available for 220 participants (124 girls), were analyzed with multiple regression. To elucidate significant effects, we predicted bone outcomes when activity volume and intensity were high (+1SD), medium (mean), and low (-1SD).
There were additive associations of volume and intensity with hip aBMD and total body BMC (low-intensity/low-volume cf. high-intensity/high-volume = [INCREMENT]0.082 g·cm and [INCREMENT]169.8 g, respectively). For males only, spine aBMD intensity was associated independently of volume (low-intensity cf. high-intensity = [INCREMENT]0.049 g·cm). For hip structural geometry, volume was associated independently of intensity (low-volume cf. high-volume = [INCREMENT]4.8-6.6%).
The activity profile associated with optimal bone outcomes was high in intensity and volume. The variation in bone health across the activity volume and intensity distribution suggests intensity is key for aBMD and BMC, whereas high volumes of lower intensity activity may be beneficial for hip structural geometry.
高强度的身体活动与骨骼健康有关，但较低强度活动的更高量可能也很重要。本研究的目的是：1）研究青少年后期积累的身体活动量和强度对 23 岁时骨骼健康的相对重要性；2）说明结果的解释。
这是爱荷华骨骼发育研究的二次分析，这是一项从儿童期到成年早期的骨骼健康纵向研究。使用 ActiGraph 原始加速度数据计算 17、19、21 和 23 岁时活动的量（平均加速度）和强度分布（强度梯度），并在各年龄平均。在 23 岁时评估髋部骨面积密度（aBMD）、全身骨矿物质含量（BMC）、脊柱 aBMD 和髋部结构几何形状（双能 X 射线吸收法，Hologic QDR4500A）。对 220 名参与者（124 名女孩）的有效数据进行了多元回归分析。为了阐明显著影响，我们预测了当活动量和强度高（+1SD）、中（平均值）和低（-1SD）时骨骼结果。
量和强度与髋部 aBMD 和全身 BMC 呈累加性关联（低强度/低量与高强度/高量相比，[增量]0.082 g·cm 和 [增量]169.8 g）。仅对于男性，脊柱 aBMD 强度与量独立相关（低强度与高强度相比，[增量]0.049 g·cm）。对于髋部结构几何形状，量与强度独立相关（低量与高强度相比，[增量]4.8-6.6%）。
与最佳骨骼结果相关的活动特征是高强度和高量。骨骼健康在活动量和强度分布上的差异表明，强度对 aBMD 和 BMC 至关重要，而较低强度活动的高量可能对髋部结构几何形状有益。
