Association between accelerometer-derived physical activity and depression: a cross-sectional study using isotemporal substitution analysis.

OBJECTIVES: Depression is a significant public health concern, and physical activity has been identified as a non-pharmacological intervention. Understanding the dose-response relationship between physical activity and depression is crucial for designing effective exercise interventions and recommending physical activity to individuals with depression. The isotemporal substitution model is considered the gold standard for estimating the dose-response effects of physical activity. This study aims to investigate the dose-response association between depression and accelerometer-measured physical activity in the Korean population.

DESIGN: Cross-sectional analysis.

SETTING: A non-probability sample of the community population was drawn from the 2014 and 2016 Korean National Health and Nutrition Examination Survey.

PARTICIPANTS: The study included 1543 adults aged 19-64 years who completed the Patient Health Questionnaire-9 (PHQ-9) and volunteered to wear an accelerometer.

MAIN OUTCOME MEASURES: Physical activity was measured using a GT3X+ accelerometer for 7 consecutive days, and activity was categorised as sedentary behaviour (SB) or light, moderate or vigorous physical activity. Depression was assessed using the PHQ-9.

RESULTS: Physical activity and SB were associated with depression. In the single-parameter model, moderate-vigorous physical activity (MVPA) showed a significant association with reduced odds of depression (OR: 0.817, 95% CI: 0.678 to 0.985). Substituting 30 min of SB with 30 min of MVPA (OR: 0.815, 95% CI: 0.669 to 0.992) was linked to a decrease in the odds of depression. Conversely, replacing 30 min of MVPA with 30 min of SB (OR: 1.227, 95% CI: 1.008 to 1.495) was associated with an increase in the odds of depression.

CONCLUSIONS: This study provides evidence of an association between physical activity and depression in the Korean population, highlighting the importance of reducing SB and increasing MVPA to prevent and manage depression. Further research is needed to confirm causality and determine optimal levels of physical activity for preventing depression in different populations.