The purpose of this study was to examine relationships between age-associated loss of muscle mass (sarcopenia), muscle strength (dynapenia) and physical functions in community-dwelling older adults. This cross-sectional study included 400 older adults (73.7 ± 5.2 years) conducted in Kasama city, Ibaraki prefecture (2011-2012). Participants were classified to following four groups based on their appendicular skeletal muscle mass (sum of skeletal muscle mass in the arms and legs evaluated by bioelectric impedance analysis), and appendicular skeletal muscle strength (grip strength for upper extremity and peak reaction force during sit-to-stand movement for lower extremity): sarcopenic-dynapenia (SD), dynapenia (D), sarcopenia (S) and non-S/non-D (NSD). We evaluated participants’ physical function using 7 physical performance tests. We conducted partial correlation analysis and analysis of covariance adjusted for age, medical history of knee pain and low back pain. Appendicular skeletal muscle strength was significantly associated with all physical performance tests in both genders (P < 0.05), however appendicular skeletal muscle mass index was not. As for the results of analysis of covariance, one-leg balance with eyes open, standing time from long sitting position, functional reach, 5-repetition sit-to-stand, timed up and go, and 5-m habitual walk were significantly poorer in SD and D groups than S and NSD groups in men. On the other hand, standing time from long sitting position, functional reach, 5-repetition sit-to-stand, timed up and go, and 5-m habitual walk were significantly poorer in D group than the S group and NSD group in women. These results suggest that dynapenia has a stronger relationship with poor physical performance than sarcopenia.
