Post Graduation Program in Movement Sciences, Sao Paulo State University - UNESP , Presidente Prudente , Brazil.
Departament of Physical Education, Universidade Nove de Julho - UNINOVE , Sao Paulo , Brazil.
Phys Sportsmed. 2019 Sep;47(3):336-340. doi: 10.1080/00913847.2019.1568770. Epub 2019 Jan 22.
: Youth is a crucial period for bone gain, and physical activity (PA) has shown to increase bone mineral density (BMD) in this period. However, whether PA affects regional BMD is unclear. Thus, the aim of this study was to analyze the relationship between PA levels and regional BMD in youths. Methods: The sample included 110 children and adolescents aged 6-14 years. Body mass, height, sitting trunk length, and leg length were obtained for body mass index and maturity offset calculation. The arms, pelvis, spine, trunk, and legs BMD were measured by double energy X-ray absorptiometry. The PA was evaluated by questionnaire, and youths were classified as low, moderately, or highly physically active. : The sample included 63.7% boys and 36.3% girls with mean age of sample 9.5 (±1.6) yrs. Age, body mass index, and maturity offset were similar between sexes (p > 0.05). Boys with low PA levels had lower BMD Z-score for arms (-0.20 ± 0.71 vs. 0.30 ± 1.19, p = 0.006) and legs (-0.14 ± 1.00 vs. 0.35 ± 1.06, p = 0.026) compared to highly physically active youths. Multiple linear regression showed a positive linear relationship between legs BMD and PA in boys (β = 0.72 [95% CI = 0.09; 1.36]). : In boys, low PA levels are associated with lower BMD in arms and legs.
: 青少年时期是骨骼生长的关键时期，身体活动（PA）已被证明可以增加这个时期的骨矿物质密度（BMD）。然而，PA 是否会影响区域 BMD 尚不清楚。因此，本研究旨在分析青少年时期 PA 水平与区域 BMD 之间的关系。
样本包括 110 名 6-14 岁的儿童和青少年。为计算体重指数和成熟度偏移，获取体重、身高、坐高和腿长。通过双能 X 射线吸收法测量手臂、骨盆、脊柱、躯干和腿部的 BMD。通过问卷评估 PA，将青少年分为低、中、高体力活动水平。
样本中男生占 63.7%，女生占 36.3%，平均年龄为 9.5（±1.6）岁。年龄、体重指数和成熟度偏移在性别之间无差异（p＞0.05）。低 PA 水平的男孩手臂（-0.20±0.71 与 0.30±1.19，p=0.006）和腿部（-0.14±1.00 与 0.35±1.06，p=0.026）的 BMD Z 评分低于高 PA 水平的青少年。多元线性回归显示，男孩腿部 BMD 与 PA 呈正线性关系（β=0.72[95%CI=0.09;1.36]）。
在男孩中，低 PA 水平与手臂和腿部较低的 BMD 有关。
