Accelerometer-measured physical activity and risk of incident ulcerative colitis: a population-based prospective study

BACKGROUND: Ulcerative colitis (UC) lacks established primary prevention strategies despite its economic burden. Physical activity (PA) is promising, yet studies using self-reported data show inconsistent results. We examined the association between accelerometer-measured physical activity and UC risk in a large prospective cohort. METHODS: This cohort study analyzed data from 95,197 UK Biobank participants without baseline inflammatory bowel disease and with valid accelerometer data, with follow-up from 2013 to 2015 through 2023. Machine learning models estimated time spent in sedentary behavior, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). MVPA patterns were categorized as active weekend warriors (≥231.5 min/week, ≥50% in 1-2 days), active regular (≥231.5 min/week, not meeting weekend warrior criteria), and inactive (<231.5 min/week). Cox proportional hazards regression assessed associations between PA and UC risk. RESULTS: Over 8.86 years median follow-up, 247 incident UC cases were recorded. MVPA showed a dose-response relationship with UC risk (trend p = 0.004). Compared to the lowest MVPA quartile, the third (231.5 to <402.3 min/week) and highest (>402.3 min/week) quartiles showed multivariable adjusted hazard ratios (aHRs) of 0.59 and 0.63 (95% CI: 0.40-0.85 and 0.43-0.91). Neither LPA nor sedentary time showed significant associations with UC risk. Both weekend warrior (aHR: 0.72, 95% CI: 0.53-0.99) and regular MVPA patterns (aHR: 0.57, 95% CI: 0.39-0.82) correlated with reduced UC risk. These associations remained robust across various subgroups and sensitivity analyses. CONCLUSION: Accelerometer-measured MVPA is associated with reduced UC risk. Both weekend warrior and regular MVPA patterns conferred protection, suggesting that flexibility in exercise scheduling may be feasible.