Can marathons damage your heart?

A new study out of Europe has linked endurance sports to heart damage, but don’t hang up your running shoes just yet.

European researchers studied 40 athletes in Australia who competed in a variety of endurance events, including marathons, endurance triathlons, alpine cycling or ultra triathlons.

The study, published on Wednesday in the online edition of the European Heart Journal, found that immediately after an endurance event, the athletes’ hearts had increased in volume and the function of the right ventricle had decreased. However, a week later, the damage had reversed itself in all by five of the 40 subjects.

But that doesn’t mean endurance activities are bad for you. Even the study’s researchers say not to use the results to avoid endurance activities.

“It is most important that our findings are not over-extrapolated to infer that endurance exercise is unhealthy,” Dr. Andre La Gerche, a postdoctoral research fellow at St. Vincent’s Hospital at the University of Melbourne, Australia, said in a news release. “Our data do not support this premise.”

“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,” he added.

“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.”

Most of the athletes in the study were also involved in long-term endurance races lasting anywhere from five to 11 hours; far longer than the average marathon run. Only seven of the 40 subjects were marathon runners.

Canadian Running senior editor Alex Hutchinson explored the issue in a blog post earlier this year about marathons and heart damage.