Endurance sports may cause abnormal heart rate and rhythm in some athletes that can lead to a rare but life-threatening condition, Belgium researchers said today.
Ventricular arrhythmia (VA), a disturbance that occurs in the ventricles or lower chambers of the heart, is a condition that can cause sudden death in top athletes who have had no previous symptoms of the disorder.
After studying Dutch and Belgian endurance athletes with VA and other healthy sportspeople and volunteers, the researchers found that in the athletes with the problem, the right ventricle (RV) of the heart was not functioning normally.
They believe VA, which could have many underlying causes, may be triggered by intense exercise or that endurance sports could promote the arrhythmia along with genetic or environmental factors.
"Our study does not provide definitive proof for either of these explanations, but our data contribute to the accumulating, indirect evidence that endurance exercise may have detrimental effects on the RV in some athletes," said Professor Hein Heidbuchel of the University of Leuven in Belgium.
The scientists, who reported their findings in the European Heart Journal, used X-rays of the heart and measured the volume of blood flow in the right ventricle and the thickness of the walls in the chamber for the study.
The abnormality in the right ventricle they uncovered in the athletes was more subtle than in people whose VA is due to a genetic cause.
The researchers said other studies suggest that endurance exercise subjects the thin walls of the right ventricle to an increased workload that may lead to the structural changes in the chamber.
"Determining the underlying genetic profile of these athletes may provide further data and that work is under way," said Mr Heidbuchel.
"We also do not know whether substance abuse may have contributed to the observed changes, although all study subjects denied such use and there was no other evidence for it in any of them," he added.