Age-related differences across the adult lifespan: a comparison of six field assessments of physical function.

Background: Age-related declines in physical capabilities often result from decreased lower-limb muscle strength and power, which are measurable through field tests. Various tests can detect functional declines in older adults, but their responsiveness to age-related differences is less understood in those without substantial impairments. Therefore, this study evaluated and compared the ability of field tests to detect age-related changes in physical and muscle function across adulthood.

Methods: 304 participants (52% female; 19-85 years) completed six field tests: handgrip strength (HGS), maximal gait speed (MGS) over a 10-m course, 5-repetition sit-to-stand power (STSP), timed up and go (TUG), countermovement jump (CMJ), and stair climbing power (SCP). Segmented regression analysis determined the relationship between age and field test performance, and identified the age at which the rate of decline increased. A multilevel linear mixed model compared decline rates between tests.

Results: Before 60 years, SCP and CMJ were responsive to age-related differences (-0.70 to -0.81%/year, p < 0.05), whereas TUG and STSP (lower age-related decline, -0.18% to -0.52%/year, p < 0.05) and HGS and MGS (no significant age-related decline) exhibited lower responsiveness. After 60, most tests (except the STSP) demonstrated increased responsiveness to age-related differences, although these differences remain most pronounced in SCP and CMJ (-1.61 to -1.75%/year, p < 0.05).

Conclusions: These findings imply that most field tests are responsive to age-related declines in physical and/or muscle function after 60. In younger age groups, field tests that evaluate lower-limb power and have minimal ceiling effects, such as SCP and CMJ, should be prioritized.