Musculoskeletal disorders are common among older people. Preventive strategies require understanding of age-related changes in strength, function and body composition, including how they interrelate. We have described, and examined associations between, 9-year changes in these parameters among 2917 Health, Aging and Body Composition Study participants (aged 70-79 years). Appendicular lean mass (ALM), whole body fat mass and total hip BMD were ascertained using DXA; muscle strength by grip dynamometry; and muscle function by gait speed. For each characteristic annualised percentage changes were calculated; measures of conditional change (independent of baseline) were derived and their interrelationships were examined using Pearson correlations; proportion of variance at 9-year follow-up explained by baseline level was estimated; and mean trajectories in relation to age were estimated using linear mixed models. Analyses were stratified by sex. Median [lower quartile, upper quartile] annual percentage declines were grip strength (1.5 [0.0, 2.9]), gait speed (2.0 [0.6, 3.7]), ALM (0.7 [0.1, 1.4]), fat mass (0.4 [- 1.1, 1.9]) and hip BMD (0.5 [0.0, 1.1]). Declines were linear for ALM and accelerated over time for other characteristics. Most conditional change measures were positively correlated, most strongly between ALM, fat mass and hip BMD (r > 0.28). Proportion of variation at follow-up explained by baseline was lower for grip strength and gait speed (39-52%) than other characteristics (69-86%). Strength and function declined more rapidly, and were less correlated between baseline and follow-up, than measures of body composition. Therefore, broader intervention strategies to prevent loss of strength and function in later life are required as those targeting body composition alone may be insufficient.

中文翻译：

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肌肉骨骼老化和身体组成的长期变化率：《健康，衰老和身体组成研究》的发现。

肌肉骨骼疾病在老年人中很常见。预防策略需要了解与年龄相关的力量，功能和身体组成的变化，包括它们之间的相互关系。我们已经描述并检查了2917名健康，衰老和身体成分研究参与者（年龄70-79岁）中这些参数的9年变化之间的关联。使用DXA确定阑尾瘦体重（ALM），全身脂肪质量和总髋部BMD。握力法测肌力; 和肌肉的步态速度。对于每个特征，计算出年度百分比变化；得出条件变化的量度（独立于基线），并使用Pearson相关性检验它们之间的相互关系；估计了由基线水平解释的9年随访中的差异比例；使用线性混合模型估算了与年龄相关的平均轨迹。分析按性别分层。[下四分位数，上四分位数]年均下降百分比为握力（1.5 [0.0，2.9]），步态速度（2.0 [0.6，3.7]），ALM（0.7 [0.1，1.4]），脂肪量（0.4 [- 1.1，1.9]）和髋部BMD（0.5 [0.0，1.1]）。对于ALM，下降是线性的，而对于其他特性，下降则随时间加速。大多数条件变化测量值均呈正相关，ALM，脂肪量和髋部BMD之间的相关性最大（r> 0.28）。基线所解释的随访时变异的比例，其握力和步态速度（39-52％）低于其他特征（69-86％）。与身体成分的测量值相比，力量和功能下降得更快，并且基线和随访之间的相关性较小。因此，