Abstract
BACKGROUND: Physical function declines with ageing; however, the changes in the prevalence of impaired physical function during ageing and how the changes would be affected by physical activity are not well investigated. This study aimed to address the issues. METHODS: We included participants aged ≥ 65 years in the 2008-2010 wave, who were followed-up in the 2012-2014 and the 2016-2018 waves of the Health and Retirement Study. Types of impaired physical function included weak grip strength, slow walking speed, and poor standing balance. Their prevalence in each wave was calculated and their changes over time were estimated using the mixed-effects logistic regression model. RESULTS: A total of 6,537 older adults were included. The prevalence of slow walking speed ranked the highest in all the types of impaired physical function in all the 3 individual waves (all P(comparison) <0.001). During follow-up, participants were increasingly being older and the prevalences of all the types of impaired physical function were gradually increased after multivariate-adjustment (all P(trend) <0.001). These increases were unlikely to be significantly moderated by weight status, drinking history or the presence of diabetes (all P(interaction) ≥0.19). However, the increases in the prevalences of weak grip strength and slow walking speed were nonsignificant in participants with regular physical activity, but was significant in those without (P(interaction) = 0.009 and 0.01, respectively). CONCLUSIONS: Despite gradual increases in the prevalence of impaired physical function during ageing, regular physical activity may help to preserve physical function in older adults. CLINICAL TRIAL REGISTRATION: Not applicable.