Why are endurance athletes more prone to abnormal heart rhythms?

Molecular mechanisms underlying exercise training-induced arrythmias

Our heart requires an electrical signal to beat correctly. When this signal breaks down, disturbances in the heart beat called arrhythmias occur. Arrhythmias can cause serious health problems and even sudden death. We know that athletes who perform long-term intense exercise training are more prone to several types of arrhythmia but we do not understand why these heart rhythm disturbances develop. With BHF funding, Professor Mark Boyett and his colleagues from the University of Manchester have already found that, in an animal model, even a short period of training can alter the electrical activity in the pacemaker of the heart, and could help explain why athletes often have a slow heart rate. The researchers think that similar changes occur in the rest of the heart muscle and may be responsible for the arrhythmias. The team have now been awarded a further grant from the BHF to find out, in mice, exactly how exercise causes changes in the gene expression and proteins of the heart, and if any changes have a negative effect on the electrical activity of the heart. They will also investigate whether the potentially harmful effects can be reversed by stopping exercise or by treatment. This research may reveal how the electrical activity of the heart is affected by long-term intense exercise training and if there are ways we can prevent any damage.