Marathons may damage part of heart

Some endurance athletes may suffer damage to the heart's right ventricle, research shows, but the findings do not suggest that this type of exercise is unhealthy, researchers say.

The right ventricle is one of the four chambers in the heart involved in pumping blood.

The study included 40 elite athletes in Australia who competed in one of four types of endurance events: marathons, endurance triathlons, alpine cycling or ultra triathlons. The athletes were well-trained and had no known heart problems.

The athletes' hearts were assessed two to three weeks before the race, within an hour after the race, and six to 11 days after the race.

Immediately after the events, the athletes' hearts had increased in volume and the function of the right ventricle had decreased. A week later, this damage was reversed in most of the athletes but five of them (13%) showed evidence of permanent damage, with MRI showing scarring of the heart muscle (fibrosis). The five athletes had been competing in endurance sports for longer than those who did not have fibrosis.

No changes in left ventricle

None of the athletes had any changes in the left ventricle, according to the study published in the online edition of the European Heart Journal.

"Our study identifies the right ventricle as being most susceptible to exercise-induced injury and suggests that the right ventricle should be a focus of attention as we try to determine the clinical significance of these results," Dr. Andre La Gerche, a postdoctoral research fellow at St. Vincent's Hospital at the University of Melbourne, Australia, said in a journal news release.

"Large, prospective, multi-centre trials are required to elucidate whether extreme exercise may promote arrhythmias in some athletes. To draw an analogy, some tennis players develop tennis elbow. This does not mean that tennis is bad for you; rather it identifies an area of susceptibility on which to focus treatment and preventative measures," said La Gerche, who is currently based at the University Hospital Leuven in Belgium.

"It is most important that our findings are not over-extrapolated to infer that endurance exercise is unhealthy," he added. "Our data do not support this premise."

(HealthDay News, December 2011)