BMJ Group Jul 30 2025 Exercise-based cardiac rehabilitation lessens the severity, frequency, and recurrence of the most common form of irregular heart rhythm, atrial fibrillation, or AF for short, finds a pooled data analysis of the available research, published online in the British Journal of Sports Medicine. It also improves general exercise capacity and mental health, without incurring any serious side effects, the findings show. AF occurs when the heart's upper chambers (atria) don't