Association between physical activity, sedentary behavior patterns with bone health among Chinese older women

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

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.

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.

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