Effect of exercise at different loads in gene expression of both atria in male rats

Strenuous exercise increases the risk of atrial fibrillation, while moderate physical activity has been suggested to decrease its risk, Data from animal models suggest that intensive exercise, but not moderate training, increases atrial fibrosis and could be on the basis of the increased atrial fibrillation risk. The impact of the transition from moderate to strenuous exercise on atrial fibrillation risk and its underlying mechanisms remain poorly understood. We aimed to analyze biatrial remodeling after moderate and strenuous exercise. We conducted an RNA microarray of right and left atria of sedentary, mdoeratel-trained, and intensively-trained rats to uncover the mechanisms leading to atrial fibrosis in intensively trained rats. A group of male Wister rats were randomized into a moderate exercise (mod, 35 cm/s for 45 min, 5 days/week), strenuous exercise (int, 60 cm/s for 60 min, 5 days/week), or a sedentary group for 16 weeks.