INTRODUCTION: The relationship between physical activity behavior and subsequent falls in adults from midlife to older age is unclear. Falls and fall-related injuries could lessen physical activity participation. This study examined patterns and bidirectional associations between physical activity and falls from midlife to older age. METHODS: In the Australian Longitudinal Study on Women's Health, women born 1946-1951 (n=11,759, mean age: 56 years at baseline in 2004) self-reported weekly physical activity amounts (0, 1-<
150, 150-<
300, ≥300 minutes/week) and noninjurious and injurious falls every 3 years between 2004 survey and 2019 survey. Bidirectional prospective 3-year associations between physical activity and falls were examined using generalized estimating equations to estimate ORs and 95% CIs, adjusting for directed acyclic graph-informed covariates. Analyses were conducted in 2023. RESULTS: Participation in any amount of physical activity was associated with a reduced risk of injurious falls (OR CONCLUSIONS: The prospective bidirectional association between physical activity and falls supports addressing falls by promoting activity and highlighting the impact of injurious falls on reduced physical activity participation.