Athletes face an increased risk of developing abnormal heart rhythms in old age, leading to them needing pacemakers, new research suggests.
A team from Manchester University, UK, looked at the possible impact of a lifetime of training and competing in endurance events such as marathons, triathlons and iron man challenges.
They tested rodents to view the effects of long-term strenuous activity on the heart, particularly focusing on heart rhythm disturbances known as arrhythmias. This showed that molecular changes take place in the heart’s pacemaker.
Researcher Dr Alicia D’Souza explains: "The heart rate is set by the heart’s pacemaker, but this is controlled by the nervous system. The ‘vagal’ nerves lower the heart rate and therefore it was assumed the low heart rate of athletes is the result of over activity of the vagal nerves.
"But our research shows this is not the case. Actually the heart’s pacemaker changes in response to training and in particular there is a decrease in an important pacemaker protein, known as HCN4, and this is responsible for the low heart rate." Details of the findings are reported in Nature Communications today (14 May).
Co-author Professor Mark Boyett said: "This is important because although normally a low resting heart rate of an athlete does not cause problems, elderly athletes with a lifelong training history are more likely to need an artificial electronic pacemaker fitted."
But he added: "Although endurance exercise training can have harmful effects on the heart, it is more than outweighed by the beneficial effects."
Professor Jeremy Pearson of the British Heart Foundation, which partly funded the research, commented: "If the findings are reproduced in humans they could have implications for heart health in older athletes. But much more research is needed before we could draw that conclusion."
D’Souza, A. et al. Nature Communications 14 May 2013.
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