Abstract
Studies on the relationship between physical activity (PA) and depression often rely on self-reported data, with a predominant focus on moderate-to-vigorous physical activity (MVPA). However, research examining accelerometer-measured PA, particularly light physical activity (LPA), and its impact on depression risk in the general population remains limited. This study explores the dose-response relationship between accelerometer-measured PA and depression, with a particular focus on varying PA intensities and high-risk groups for depression, including women and individuals with obesity. This prospective cohort study involved 90,585 participants with accelerometer-measured PA data from the UK Biobank Study. Total PA volume was assessed using the average overall acceleration (ACC). Weekly minutes of LPA, moderate PA (MPA), and vigorous PA (VPA) were recorded. Incident cases of clinical depression were identified through diagnostic codes linked to hospital records and death certificates. Cox proportional hazards models with restricted cubic splines were used to analyze the associations. During an average follow-up period of 8.35 ± 0.97 years, 1,641 participants (2.2 per 1,000 person-years) developed depression. Depression risk decreased as total ACC reached 30 mg and as time spent in LPA, MPA, and VPA increased to 2000, 500, and 50 min per week, respectively, beyond which no further reduction in risk was observed. Higher-intensity PA, particularly VPA, did not provide additional benefits for depression when total PA volume was comparable. The relationship between LPA and depression risk was moderated by gender and obesity status, with no significant risk reduction observed in women and individuals with obesity engaging in LPA. Device-measured PA across all intensities, including LPA, MPA, and VPA, was associated with a reduced risk of depression, though the reduction was more dependent on PA volume than intensity. A threshold effect was observed, beyond which additional benefits diminished. Nonetheless, MVPA remains recommended for women and individuals with obesity.