The independent and joint association between physical activity, sleep duration and daily sitting time with bone mineral density: A real world study from NHANES 2007–2018.

Purpose

To assess the independent and joint effect of physical activity, sleep duration, and daily sitting time on bone mineral density (BMD), based on National Health and Nutrition Examination Survey (NHANES) 2007–2018.

Design

Cross-sectional design.

Methods

The primary outcome was risk of low BMD. All associations between lifestyle factors and the prevalence of low BMD were based on logistic regression, and dose-response relationships were further explored by restricted cubic spline (RCS). Finally, multiplicative and additive interaction was examined by P _interaction and relative excess risk due to interaction (RERI).

Results

10,346 individuals (N _{normal BMD} = 6353; N _{Low BMD} = 3993) were analyzed. Multivariate logistic regression indicated low intensity physical activity (odds ratio [OR] 0.84; 95 % confidence interval [95%CI] 0.78–0.90) and high intensity physical activity (0.67, 0.56–0.78) had protective impact on risk of low BMD, whereas short sleep (1.41, 1.20–1.64), long sleep (1.36, 1.03–1.79) and prolonged daily sitting (1.58, 1.32–1.88) had harmful effect. RCS revealed dose-response associations between physical activity (J-shaped), sleep duration (U-shaped), daily sitting time (positive-associated) and risk of low BMD. Multiplicative interaction between sleep duration and physical activity was observed (P _interaction = 0.003), while not between daily sitting time and physical activity (P _interaction = 0.600). Notably, negative additive interactions indicated that physical activity mitigated the increased risk of low BMD associated with irregular sleep patterns and prolonged sedentary behavior.

Conclusion

Increasing physical activity was presented as a modulating factor, potentially altering the relationship between independent variables that have deleterious effects on BMD like sleep duration and sedentary behavior. The study underscores the importance of lifestyle modifications in the prevention of early onset low BMD.