But a new study of former Olympians and other athletes suggests that, while years of putting in the miles can alter how the heart is shaped, it does not seem to cause lasting damage to its function.

Reporting in the latest issue of the journal Circulation, scientists from Saarland University in Germany looked at the hearts of 33 long-term male endurance athletes when they were training and compared their cardiac muscles to those of non-athletes of the same age. The athletes included six former Olympic triathletes, a one-time Ironman world champion and a former winner of the Munich Marathon, ranging in age from 30-60.

All participants underwent a battery of laboratory tests that included numerous high-tech scans to assess both the shape and function of their hearts. Results showed the athletes had significantly different heart muscles than the more sedentary men. In particular, their right ventricles were much larger; the left ventricles were also enlarged, although not as markedly.

However, in contrast with previous studies, the researchers found no signs these differences had any adverse effect on heart function.

In all cases, the athletes’ right ventricles pumped blood as efficiently as expected and in some cases better than normal. They also had lower resting heart rates than the non-athletes, suggesting superior cardiac health.

Dr Philipp Bohm, the sports medicine expert who led the study, said: “We found no evidence of lasting damage, pathological enlargement or functional impairment of either the right or left ventricle in the athletes who had been doing long-term, intensive, elite-level endurance exercise”. 

*This article was first published in Athletics Weekly. For more of the latest running and athletics news, plus performance features and much more, grab a copy of the magazine or check out www.athleticsweekly.com