Differences in body composition and physical functions associated with sarcopenia in Chinese elderly: reference values and prevalence.

This study investigates the age-related differences in skeletal muscle mass (SM), muscle strength and physical performance in mainland Chinese. Based on available data, the reference values (criteria) for the definition of sarcopenia in elderly Chinese were explored. Body composition measurements were obtained using a bioelectrical impedance analyzer (BIA); muscle strength was determined by handgrip strength (HS); and physical function was evaluated by the subjects' 6-m gait speed (GS). In this study, HS and GS declined significantly after 55 years and very dramatically after 75 years. Appendicular SM index of <7.61kg/m(2) (males) and <6.43kg/m(2) (females); HS of <27kg (males) and <16kg (females); and GS of <0.98m/s (males) and <0.88m/s (females) were considered as low SM, low HS and low GS. Applying these suggested criteria to the study population, there were 9.55% and 6.63% of the subjects with low SM, 20.10% and 18.46% with low GS, and 14.07% and 15.38% with low HS in elderly males and females, respectively. Utilizing Asian Working Group for Sarcopenia (AWGS) criteria in our population results in a very low prevalence of low SM and low GS. If Western criteria for sarcopenia were adopted, the prevalence of low GS and low HS would be 2-4 times higher in the studied population, also exhibiting significant gender differences. These findings indicate that it is necessary to establish an outcomes-based and ethnic-specific set of reference values for the diagnosis of sarcopenia in elderly Chinese.