How race and socioeconomic status moderate the association between moderate-to-vigorous physical activity and depressive symptoms: a cross-sectional study with compositional data.

Objectives: This study explored how race and socioeconomic status (SES) moderated the association between moderate-to-vigorous physical activity (MVPA) and depressive symptoms with compositional data.

Methods: Participants were 2803 US adults from the 2005-2006 cycle of the National Health and Nutrition Examination Survey. Accelerometers were used to measure MVPA, light-intensity physical activity (LPA) and sedentary behaviours (SB). Participants self-reported sleep duration and depressive symptoms. SES was derived by latent class analysis using household income level, education attainment and occupation. The association between the relative time of MVPA and depressive symptoms and the moderating effects of race and SES were investigated through compositional data analysis. Isotemporal substitution analysis was employed to estimate the association of time reallocation from other movement behaviours to MVPA with depressive symptoms.

Results: Increased time spent in MVPA relative to time spent in LPA, SB and sleep was inversely associated with depressive symptoms (OR (95% CI)=0.679 (0.538-0.855)). The relative time of MVPA significantly interacted with race and SES for depressive symptoms (P for interaction <0.05). Reallocating 10-30 min from sleep, SB or LPA to MVPA was associated with lower odds of depressive symptoms solely among non-Hispanic white individuals and those with higher SES.

Conclusion: This study used compositional data to reveal a reverse association between MVPA and depressive symptoms among white individuals and those with higher SES. Our results provide evidence of how race and SES moderate the relationship between MVPA and depressive symptoms. Future research is needed to further explore these racial and socioeconomic differences.