Association Between Physical Activity, Sedentary Behavior Patterns with Bone Health Among Chinese Older Women

Introduction: We examined the association between physical activity (PA) and sedentary behavior (SEB) time with bone health and whether it changes depending on different patterns.

Materials And Methods: Cross-sectional data were derived from the baseline of the Physical Activity and Health in Older Women Study. PA and SEB were measured using Actigraph wGT3X-BT accelerometers. Bone mineral density (BMD) was derived from the SONOST-2000 ultrasound bone densitometer, with unhealthy bone defined as a BMD T-score of <2.5 standard deviation a young adult reference population's mean. A 10 min-bouted SEB was defined as an SEB duration of >10 min (allow 2 min 0 counts), similar to 30 min-bouted and 60 min-bouted SEBs. Sporadic and bouted PAs were defined by PA duration of <10 min or ≥ 10 min. Multivariate logistic regression analysis investigated the associations between PA and SEB patterns with bone health.

Results: Among 1111 female participants, 42.12 % had unhealthy bones. In a fully-adjusted model, increasing 30 min/day of SEB was associated with a higher odds ratio (OR) for an unhealthy bone (OR, 1.08; P = 0.005), similar to the 10 (OR, 1.06; P = 0.012), 30 (OR, 1.06; P = 0.043), and 60 min-bouted (OR 1.08, P = 0.032) SEBs. Total light PA (LPA) time (OR, 0.97; P = 0.005) had a lower OR for unhealthy bone. After adjusting for sporadic LPA time, bouted LPA (OR, 0.97; P = 0.005) retained this association. No association was observed between total moderate-to-vigorous PA (MVPA) and bone health, sporadic MVPA, and bouted MVPA.

Conclusions: Performing bouted LPA and reducing 10 min-bouted SEB may maintain bone health.