Associations between accelerometer-measured physical activity, sedentary behaviour and pericardial adiposity: a prospective cohort study of UK Biobank participants.

INTRODUCTION: Physical activity (PA) reduces the risk of atherosclerotic cardiovascular disease by limiting the overgrowth of fat tissue, particularly visceral adiposity. However, no large-scale studies have investigated the relationship between PA and pericardial adiposity. METHODS: This study included 16 685 participants from the UK Biobank prospective cohort who underwent cardiac magnetic resonance assessment and had available PA data. PA was objectively measured using a wrist-worn triaxial accelerometer and categorised as light-intensity PA (LPA), moderate-intensity PA (MPA) and vigorous-intensity PA (VPA). Multivariable linear regression models were applied to estimate adjusted mean epicardial and pericardial adipose tissue (EPAT) areas across quartiles of total and intensity-specific PA, with linear trend analyses performed. Restricted cubic spline models were used to examine potential non-linear associations. The association between sedentary behaviour (SB) and EPAT area was also examined as a negative control. RESULTS: Accelerometer-derived PA duration across all intensities was negatively correlated with EPAT area. Participants in the highest quartile (Q4) demonstrated smaller EPAT areas relative to those in the lowest quartile (Q1), with relative mean reductions of 21.29% for total PA, 11.24% for LPA, 18.28% for MPA and 19.10% for VPA (all p trend ≤0.001). Conversely, prolonged SB showed a positive correlation with EPAT area. Compared with those in Q1, individuals in Q4 in SB presented 15.90% greater relative mean EPAT area (p for trend <0.001). After adjustment for visceral adipose tissue volume, these associations were attenuated but remained significant. Stratified analyses confirmed that PA-EPAT association persisted among individuals with atherosclerotic cardiovascular disease, diabetes, hypertension or hyperlipidaemia. Mediation analysis showed VAT largely mediated the relationship between PA and EPAT area. CONCLUSIONS: PA reduces epicardial adiposity by limiting the overgrowth of EPAT area. These findings highlight the importance of PA as a preventive strategy for improving obesity-related health management worldwide.