The purpose of this study was to examine the association of muscle mass and muscle strength with mobility limitation and history of falls in community-dwelling older adults. This cross-sectional study included 420 older adults (207 men, 213 women, 73.7 ± 5.2 years). The participants were classified to following four groups according to their appendicular skeletal muscle mass index (AMI) which was evaluated by bioelectric impedance analysis for skeletal muscle mass in the arms and legs and appendicular skeletal muscle strength Z-score (ASZ) which was calculated from hand-grip strength for upper extremity and peak reaction force during sit-to-stand movement for lower extremity: 1) Low AMI and Low ASZ, 2) Low AMI alone, 3) Low ASZ alone, and 4) Normal. Mobility limitation and history of falls were assessed as a self-reported questionnaire. We used a poisson regression analysis with an adjustment for age, body mass index, knee pain, and back pain. The prevalence of mobility limitation was significantly higher at Low AMI and Low ASZ (relative risk, RR = 5.09, 95% confidence interval, CI 2.08–12.46) and Low ASZ alone (RR = 4.79, 95% CI 2.01–11.39) in men and Low AMI and Low ASZ (RR = 1.70, 95% CI 1.01–2.88) in women than Normal. History of falls was significantly associated with Low ASZ alone (RR = 2.00, 95% CI 1.02–3.91) just in men. These results suggest that low muscle strength per weight rather than low muscle mass per height is an important risk factor to increase mobility limitation in both genders and falls in men.

Introduction: The purpose of this study was to investigate the effects that a group exercise activity managed by elderly volunteers would have on the physical function of older women after they participated in a formal exercise program taught by fitness experts.

Methods: Subjects were 47 community-dwelling older women who had completed a 3-month exercise program led by expert instructors in Kasama City, Ibaraki. After completing this exercise program, 28 subjects continued to participate in a group exercise activity led by elderly volunteers for approximately 11 months. The remaining 19 subjects did not join the group activities after the formal program. In both the initial, expert-led exercise program and the subsequent, volunteer-led group activity, subjects mainly engaged in the square-stepping exercise, which is a novel exercise for improving lower extremity physical function. In order to assess participants' physical function, we conducted five physical performance tests at both the baseline and follow-up; the former is the last day of the exercise program and the latter is approximately a year after the baseline.

Results: Two-way ANOVA demonstrated a significant interaction in the timed up and go test (P=0.003). The performance of subjects who had participated in the volunteer-managed group activity improved between the baseline and follow-up tests (P=0.007).

Conclusion: Participating in a group exercise activity managed by elderly volunteers can improve mobility skills of older women who had previously completed a formal exercise program led by expert instructors.