Abstract and Introduction
Abstract
Objective This study examines the influence of physical activity at different ages and of different types, on the risk of developing atrial fibrillation (AF) in a large cohort of Swedish men.
Methods Information about physical activity was obtained from 44 410 AF-free men, aged 45–79 years (mean age=60), who had completed a self-administered questionnaire at baseline in 1997. Participants reported retrospectively their time spent on leisure-time exercise and on walking or bicycling throughout their lifetime (at 15, 30 and 50 years of age, and at baseline (mean age=60)). Participants were followed-up in the Swedish National Inpatient Register for ascertainment of AF. Cox proportional hazards regression models were used to estimate relative risks (RR) with 95% CIs, adjusted for potential confounders.
Results During a median follow-up of 12 years, 4568 cases of AF were diagnosed. We observed a RR of 1.19 (95% CI 1.05 to 1.36) of developing AF in men who at the age of 30 years had exercised for >5 h/week compared with <1 h/week. The risk was even higher (RR 1.49, 95% CI 1.14 to 1.95) among the men who exercised >5 h/week at age 30 and quit exercising later in life (<1 h/week at baseline). Walking/bicycling at baseline was inversely associated with risk of AF (RR 0.87, 95% CI 0.77 to 0.97 for >1 h/day vs almost never) and the association was similar after excluding men with previous coronary heart disease or heart failure at baseline (corresponding RR 0.88, 95% CI 0.77 to 0.998).
Conclusions Leisure-time exercise at younger age is associated with an increased risk of AF, whereas walking/bicycling at older age is associated with a decreased risk.
Introduction
Regular physical activity contributes to the prevention and management of many diseases and medical conditions, such as cardiovascular disease, cerebrovascular disease, hypertension, obesity, diabetes mellitus, osteoporosis, some malignancies and mental illness. The impact of physical activity on the risk of atrial fibrillation (AF) appears to be more complex. Several small case-control studies have reported that long-term regular sport activity elevates the risk of AF in young and middle-aged men. One recent large cohort study of men and women participating in a 90 km cross-country skiing event reported elevated risk of arrhythmias including AF among men and women with the fastest finishing times and greatest number of completed races. On the other hand, a prospective study of older men and women observed a reduction in risk of AF with moderate-intensity physical activity, including leisure-time exercise and walking, but found no increase in risk with high-intensity physical activity. This implies that physical activity of different intensities could have different effects on the risk of developing AF later in life.
The vast majorities of previous studies investigated athletes and individuals participating in sport competitions. Large studies investigating the association between physical activity and AF in a general population are lacking.
This study examines the associations of physical activity at different ages and of different types, with risk of developing AF in a large general population. We examined the relationship between various types of physical activity at different ages and the risk of AF in a large population-based prospective cohort of Swedish men. We hypothesised that leisure-time exercise (considered as moderate-intensity to high-intensity activity) increases the risk of developing AF later in life, while walking/bicycling for transportation (low-intensity to moderate-intensity) decreases the risk.