Sarcopenia, age related skeletal muscle decline, is a primary factor of physical dysfunction and mobility disability. The relative expansion of extra-cellular water (ECW) is observed during aging, and thus, sarcopenia must be assessed by body cell mass or intra-cellular water (ICW). The aims of the present study were 1) to validate the newly developed segmental multi-frequency bioelectrical impedance analysis (S-MFBIA) to estimate ICW compared with chemical dilution techniques, 2) to clarify the relationship between segmental ICW and muscle strength in the elderly, 3) to examine the age related change of ICW and calculate the cutoff of sarcopenia, and 4) to examine the relationship between daily physical activity and sarcopenia. S-MFBIA was highly correlated with ICW measured by chemical dilution methods and muscle strength. The ICW estimated by S-MFBIA was significantly decreased with aging in a total of 592 Japanese adults and the cut-off values of sarcopenia were established using those data. The daily physical activity and steps recorded by tri-axial accelerometers were strongly and significantly related to sarcopenia. The results suggest that S-MFBIA is useful to assess age related skeletal muscle loss and the daily physical activity, especially the activity of 3 METs or more intensity may be important to prevent sarcopenia.

DESCENTE SPORTS SCIENCE Vol.32/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE