BACKGROUND: Previous findings regarding physical activity and risk of incident atrial fibrillation (AF) are controversial, focusing on leisure-time physical activity (LTPA) and without distinguishing it from occupational physical activity (OPA). Our aim was to study the association between physical activity and risk of AF, with special attention to the possible divergent effects of OPA and LTPA.

METHODS AND RESULTS: In a prospective, observational cohort study, 17,196 subjects were included from the Copenhagen Population Register. All participants had a physical examination, a 12-lead electrocardiogram (ECG), and answered a questionnaire regarding health and physical activity. Participants without previously diagnosed AF who answered adequately regarding OPA and LTPA were included. LTPA and OPA were each graded into four levels. Follow-up were carried out between 1981-1983, 1991-1994, and 2001-2003. Information regarding hospitalization and mortality was drawn from the National Patient Registry and the Registry of Causes of Death. Outcome was incident AF as determined by follow-up ECG or register diagnosis. In univariable Cox regression analysis all sub-groups of OPA had a significant higher risk of AF compared to moderate OPA. When adjusting for confounders, the risk remained significantly increased for high OPA (hazard ratio (HR) 1.21 (95% confidence interval (CI) 1.02-1.43), p = 0.028), and very high OPA (HR 1.39 (95% CI 1.03-1.88), p = 0.034). We found no significant association between LTPA and incident AF.

CONCLUSIONS: High and very high OPA were associated with a significantly increased risk of incident AF. LTPA was not associated with risk of incident AF.