Abstract
To determine the cross-sectional associations of accelerometer-measured time spent in physical activity intensity categories (sedentary, low and high light intensity, or moderate to vigorous intensity physical activity (MVPA) with physical performance outcomes [stair climb ascent, 40 foot walk test, and short physical performance battery (SPPB)] in older women and examine differences by race/ethnicity. Data were from 1,256 Study of Women's Health Across the Nation (SWAN) participants [aged 64.9 (2.7) years at Visit 15 (2015-16); 54.1% non-White]. Three sets of adjusted multivariable linear or logistic regression models were built to test the study objectives using the backward elimination approach to identify relevant covariates. In the full analytic sample, a 10 min increment in MVPA was related to faster performance on the stair climb [β = -0.023 (95% CI: -0.04, -0.005) seconds] and 40 foot walk test [β = -0.066 (95% CI: -0.133, -0.038) seconds], and a 9% lower odds [OR: 0.91; 95% CI: 0.87, 0.96; p = 0.004] of limitations based on the SPPB. Statistically significant differences by race/ethnicity were found for the stair climb ascent time as MVPA was associated with better performance for White, Chinese, and Japanese participants while high light intensity physical activity, but not MVPA, was deemed beneficial in Black women. Findings from the isotemporal substitution models were consistent. Findings further support the importance of MVPA on physical performance outcomes in older women. Further research is needed to examine the complex associations between physical (in)activity and physical performance outcomes by race/ethnicity to provide more targeted recommendations.