Background/Objectives : Women 65 and older experience nearly three-fourths of the 2 million osteoporotic fractures annually in the United States. We investigated associations of accelerometer-measured total physical activity, light physical activity, moderate-to-vigorous physical activity (MVPA), steps, total sitting time, and mean sitting bout duration with incident osteoporotic fracture. Methods : Women from the Objective Physical Activity and Cardiovascular Health cohort ( N = 6,122; mean age: 78.7; SD : 6.7) without prior hip fracture wore the ActiGraph GT3X+ up to 7 days and were followed up to 8 years for incident osteoporotic fractures ( n = 982). Cox regression models estimated hazard ratios and 95% confidence intervals (CI) additionally containing age, race/ethnicity, education, alcohol, smoking, height, weight, falls, physical functioning, diabetes, thiazide use, and anti-osteoporosis medication use. Results : Multivariable HRs (95% CI) were 1 (ref), 1.10 0.93, 1.31, 0.93 0.77, 1.13, and 0.87 0.70, 1.07 across MVPA minutes/quartiles ( p -trend = .03) and 1 (ref), 1.10 0.90, 1.33, 1.21 1.00, 1.47, and 1.27 1.04, 1.57 across total sitting time quartiles ( p -trend = .02). The hazard ratios (95% CI) for a one- SD increment in MVPA (33 min/day) and total sitting time (103 min/day) were 0.92 0.85, 0.99 and 1.09 1.01, 1.18, respectively. The hazard ratios (95% CI) for MVPA and osteoporotic fracture was 0.82 0.73, 0.93 among women not using anti-osteoporosis medication and 1.06 0.90, 1.24 among women using anti-osteoporosis medication ( p -interaction = .02). Conclusions : More MVPA and less total sitting time, but not other accelerometer measures, were associated with lower osteoporotic fracture risk. Significance/Implications : These data support interventions and physical activity guidelines aimed at promoting moderate- or vigorous-intensity movement and decreased sitting for osteoporotic fracture prevention.
Nguyen et al. (Thu,) studied this question.