A British Heart Foundation team found exercise in mice triggers molecular changes in the part of the heart that generates its natural beating rhythm.
This may explain why elite athletes have low resting heart rates and a higher risk heart rhythm disturbances, they told Nature Communications.
Endurance athletes are generally very fit.
Yet, paradoxically, they are more likely to have heart rhythm disturbances, known as arrhythmias, especially as they get older - although the risk is still small.
