A cross-sectional study of loss of muscle mass corresponding to sarcopenia in healthy Chinese men and women: reference values, prevalence, and association with bone mass

A cross-sectional survey was conducted in Shanghai, eastern China, to evaluate the prevalence of loss of muscle mass corresponding to sarcopenia in Chinese men and women and compare the results with the prevalence in other populations. We also analyzed the differences between men and women, and assessed the effect of lean mass and fat mass of different regions on bone mass. A total of 1766 men and 1778 women aged 18-96 years participated in this study. Bone mineral density of spine and femur, and lean mass and fat mass of several body regions were measured by dual-energy X-ray absorptiometry. Class 1 and class 2 sarcopenia were defined as the appendicular lean mass (ALM) index (ALM/height(2)) 1 and 2 standard deviations below the sex-specific means for young adults. Mean values for ALM index were 7.93 for men and 6.04 kg/m(2) for women, aged 18-40 years. The reference values for classes 1 and 2 sarcopenia were 7.01 and 6.08 kg/m(2) in men and 5.42 and 4.79 kg/m(2) in women. The prevalence of sarcopenia was 4.8 % in women and 13.2 % in men aged 70 years and older, which is lower than that in Caucasian populations, but the same as that in Japanese and Koreans in Asia. Men demonstrated greater declines in muscle mass with aging than women, partly due to the protective effect of fat mass on lean mass in women. Leg lean mass was the strongest factor on femur bone mass; however, trunk lean mass was the strongest factor on spine bone mass. Maintaining a healthy weight is important for the elderly in order to avoid osteoporosis and sarcopenia.