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J Gerontol A Biol Sci Med Sci. 2014 Jan;69(1):93-100. doi: 10.1093/gerona/glt027. Epub 2013 May 16.
Older women have higher percent body fat, poorer physical function, lower strength, and higher rates of nonfatal chronic conditions than men. We sought to determine whether these differences explained physical performance differences between men and women.
Physical performance was assessed in the Health, Aging and Body Composition study in 2,863 men and women aged 70-79 with a composite 0-4 point score consisting of chair stands, standing balance including one-leg stand, and 6-m usual and narrow walk tests. Total body composition was measured by dual x-ray absorptiometry, thigh composition by computed tomography, and knee extensor strength by isokinetic dynamometer. Analysis of covariance estimated least square mean performance scores for men and women.
Men had higher performance scores than women (least square means: 2.33±0.02 vs 2.03±0.02, p < .0001), adjusted for race, study site, age, and height. Body composition measures (total body fat and thigh muscle area, muscle density, subcutaneous fat, and intermuscular fat) accounted for differences between men and women (least square means: 2.15±0.02 vs 2.17±0.02, p = .53). Higher strength in men partly explained the sex difference (least square means: 2.28±0.02 vs 2.12±0.02, p < .0001). Strength attenuated the association of thigh muscle mass with performance. Chronic health conditions did not explain the sex difference.
In a well-functioning cohort, poorer physical function in women compared with men can be explained predominantly by their higher fat mass, but also by other body composition differences. The higher proportion of body fat in women may put them at significant biomechanical disadvantage for greater disability in old age.
与男性相比，老年女性体脂百分比更高、身体机能更差、力量更弱、非致命性慢性疾病发病率更高。我们试图确定这些差异是否可以解释男性和女性在身体机能表现方面的差异。
在健康、衰老和身体成分研究中，我们对 2863 名年龄在 70-79 岁的男性和女性进行了身体机能表现评估，采用包含椅子站立测试、站立平衡测试（包括单腿站立测试）和 6 米常规及变窄行走测试的综合 0-4 分评分。通过双能 X 线吸收法测量全身成分，通过计算机断层扫描测量大腿成分，通过等速测力计测量膝关节伸肌力量。协方差分析估计了男性和女性的最小平方均数表现评分。
与女性相比，男性的表现评分更高（最小平方均值：2.33±0.02 对 2.03±0.02，p<0.0001），调整了种族、研究地点、年龄和身高因素。身体成分测量值（全身脂肪和大腿肌肉面积、肌肉密度、皮下脂肪和肌肉间脂肪）解释了男性和女性之间的差异（最小平方均值：2.15±0.02 对 2.17±0.02，p=0.53）。男性更强的力量部分解释了性别差异（最小平方均值：2.28±0.02 对 2.12±0.02，p<0.0001）。力量减弱了大腿肌肉质量与表现之间的关联。慢性健康状况并不能解释性别差异。
在功能良好的队列中，与男性相比，女性身体机能更差，这主要可以归因于其更高的脂肪量，但也与其他身体成分差异有关。女性体内脂肪比例较高可能使她们在老年时面临更大的残疾风险处于显著的生物力学劣势。
