Associations of Accelerometer-Measured Physical Activity and Sedentary Behavior With Incident Clinical Osteoporotic...

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.

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.

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).

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.