Long-term participation in community group exercise improves lower extremity muscle strength and delays age-related declines in walking speed and physical function in older adults

BACKGROUND: The effects of group exercise on the physical function of community-dwelling older adults remain unclear. The changes in lower extremity muscle strength, timed up and go (TUG) time, and the motor fitness scale (MFS), over time, among older adults who expressed a willingness to participate in community-based physical exercise groups, were determined using multilevel modelling. METHODS: We analyzed data of 2407 older adults between April 2010 and December 2019 from the registry of physical tests of community-based physical exercise groups. We conducted a retrospective cohort study to assess the effect of physical exercise on lower extremity muscle strength, TUG time, and MFS scores. The durations of the exercises were evaluated by frequency of physical test’s participate. RESULTS: A deterioration in lower extremity muscle strength was found in the short-term participant group only. However, in the mid-term and long-term participation groups, lower extremity muscle strength showed a trend of improvement. The TUG time and the MFS score were negatively correlated with increasing age in both groups divided by the duration of participation. However, there was a slower rate of deterioration in the long-term participation group. DISCUSSION: Lower extremity muscle strength, TUG time, and MFS scores decline with increasing age and there were differences in the slope of deterioration that depended on the duration of participation in community-based group exercise. CONCLUSION: Participation in group exercise improved lower extremity muscle strength, TUG time, and MFS scores of older adults living in a community. The positive effects of group exercise were dependent on long-term participation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s11556-021-00260-2.