The aims of this study were to investigate the longitudinal changes in muscle and bone with aging, and to clarify the muscle–bone relationships.

In a community-based prospective study, a total of 172 men and 165 women aged ≥ 65 years who had performed body composition analysis and bone mineral density (BMD) by dual-energy x-ray absorptiometry at baseline and 5-year follow-up evaluations were included.

The rate of BMD loss in total hip was significantly associated with baseline legs lean mass and loss rate of leg strength, but not with the rate of muscle mass losses in men (r = .205 in leg lean mass, r = .170 in loss rate of leg muscle strength, p < .05 respectively). However, in women, it was significantly correlated with the rate of leg lean mass loss, but not with baseline values, and the rate of loss in leg muscle strength (r = .169 in the rate of loss in leg lean mass, r = .246 in the rate of loss in leg muscle strength, p < .05 respectively). In multivariate analyses, the rates of decrease in leg muscle strength showed independent positive associations with loss in total hip BMD in both men and women (β = 0.023 for men and β = 0.045 for women, both p < .05 respectively).

There was a gender difference in muscle and bone mass changes with aging, and muscle–bone interactions as well. However, a longitudinal change in muscle strength was the most significant independent factor associated with bone loss for both genders.