Associations of leisure-time physical activity with muscle strength and functional fitness domains among community-dwelling older adults: a cross-sectional study

Declines in muscle strength and functional fitness in older adults are associated with multiple adverse outcomes, yet the associations between leisure-time physical activity(LTPA) and multidimensional objective functional measures remain unclear.

The linked source sample comprised 466 community-dwelling older adults who completed both the questionnaire survey and physical fitness assessments and were successfully matched at the individual level. Analyses were conducted using analysis-specific complete-case samples, with 418 participants included in the primary grip strength model. The primary exposure was total weekly LTPA, and the secondary exposure was average daily sedentary time (ST). The primary outcome was grip strength, and the secondary outcomes included the 30-s chair stand test, eyes-closed balance, choice reaction time, and a composite functional fitness Z score. Ordinary least squares (OLS) linear regression with HC3 robust standard errors was used, with sequential adjustment for sociodemographic, lifestyle, and health-related covariates. LTPA tertile analyses and sensitivity analyses were also conducted.

In the fully adjusted model, each additional 60 min/week of LTPA was associated with higher grip strength (β = 0.064 kg, 95% confidence interval (CI) 0.009 to 0.120). This association persisted after further adjustment for ST, and the direction of the association remained broadly consistent after excluding current smokers or participants with a greater chronic disease burden. In contrast, no clear independent associations were observed between LTPA and the 30-s chair stand test, eyes-closed balance, choice reaction time, or composite functional fitness Z score. Tertile analyses showed no consistent trends. ST was likewise not independently associated with grip strength or any functional fitness measure.

Among community-dwelling older adults, higher LTPA levels were associated with slightly greater grip strength, although the absolute effect size was small and its clinical significance remains uncertain. ST was not consistently associated with grip strength or functional fitness measures in this study. Across objective functional outcomes in older adults, the association of LTPA may be more pronounced for the muscle strength domain than for other functional fitness domains.