Study on the life fitness in Japanese

本研究的目的是：1)开发一个大样本的肌肉质量和功能测量系统；2)利用该系统记录日本人日常生活(生活健康)中的体力工作能力；3)调查维持和/或改善生活健康所需的锻炼计划的内容。主要研究结果如下。1)超声测量肌肉厚度和生物电阻抗分析有助于准确估计肢体肌肉的体积。2)与年龄相关的肌肉质量损失，下肢肌肉大于上肢肌肉。尤其是膝关节伸肌，与肢体上的其他肌肉相比，与年龄相关的丧失发生在较早的几代人。此外，随着年龄的增长，腹部肌肉也显示出更大的损失，与膝关节伸肌的损失幅度相似。3)对于肢体肌肉，衰老对发电能力的影响大于对肌肉力量的影响。4)对于老年女性来说，以自身身体质量为阻力的锻炼方案能有效地改善身体成分和下肢肌肉的发电能力。此外，老年女性的每日步行步数与膝关节伸展扭矩与肌肉体积或跟骨骨强度之间存在显著的相关性。

This study aimed 1) to develop a measurement system for assessing muscle mass and function in a large sample, 2) to document the physical working capacity in daily life (life fitness) in Japanese by the use of the system, and 3) to investigate the content of exercise programs required to maintain and/or improve life fitness. The main findings were as the following. 1) Ultrasonograpphic muscle thickness measurement and bioelectrical impedance analysis are useful for estimating accurately the volume of limb muscles. 2) Age-related loss of muscle mass is greater in the lower limb muscles than in the upper limb muscles. Especially, for the knee extensor muscles the age-related loss occurs in the earlier generations as compared to other muscles located in limb. In addition, the abdominal muscle also shows a greater loss with aging with a similar magnitude as observed in the knee extensors. 3) For the lower limb muscles, the influence of aging on the power generation capabilities is greater than that on muscle strength. 4) For elderly women, exercise program with their own body masses as a resistance is effectiveness to improve body composition and power generation capability of lower limb muscles. Moreover, there is a significant correlation between walking step per day and either knee extension torque relative to muscle volume or the bone intensity of calcaneus in elderly women.