(RxWiki News) Endurance athletes that participate in long-term exercise such as marathons, triathlons and alpine cycling could be at risk of developing permanent damage to the heart's right ventricle.
This could especially be true among athletes with a genetic predisposition toward developed damage to that side of the heart.
"Exercise to encourage a healthy heart."
Dr. André La Gerche, a postdoctoral research fellow at St Vincent’s Hospital through Australia's University of Melbourne, but currently based at the University Hospitals Leuven in Belgium, stressed that the findings did not suggest that endurance exercise is unhealthy. The results did not support that conclusion, he said.
During the study researchers followed 40 elite Australian athletes planning to compete in an endurance event. The athletes trained at least 10 hours a week, finished toward the top in their events and had no known heart problems.
Investigators performed blood tests, used echocardiography and took MRIs of the heart muscle to check for damage to the right ventricle. The tests were each performed three times: once two or three weeks before the race, within one hour of completing the race, and between six and 11 days after the race.
They found that five of them, or 13 percent, had permanent scarring of the heart muscle. Those participants had been competing in endurance sports longer than the other competitors.
In addition, following a race the athletes' hearts had changed shape and had increased volume, but reduced ventricle function. Researchers also found increased levels of B-type natriuretic peptide (BNP), a chemical secreted by the heart's ventricles after excessive stretching of heart muscle cells. No change was found in the left ventricle.
Most of the changes in the hearts of the athletes had recovered a week after taking part in a competitive event. Dr. Gerche said that in most athletes sensible training combined with an adequate recovery period rebuilds the heart so that it is more capable of sustaining similar exercise in the future.
The research, however, suggested some athletes may not experience that recovery, potentially putting those athletes at risk of reduced performance from cardiac "over-training" syndrome, or heart arrhythmias. The affected number of athletes who do not experience recovery is believed to be small, and increased by longer duration races.
Researchers called for additional multi-center trials to determine whether excessive exercise could promote heart arrhythmias in some athletes.
The research was recently published in the European Heart Journal.