Study suggests older male endurance athletes have greater heart rhythm risk

The study, led by a team at the University of Leeds, published in the journal Circulation: Cardiovascular Imaging suggests those who have spent decades training and competing are more likely to have scarring in their hearts than non-athletes.  

While scarring occurs in many heart conditions, recent studies have suggested some lifelong endurance athletes – particularly older men – may have the condition without presenting other symptoms of heart problems. 

However, those athletes with scarring were more than 4.5 times more likely to experience an abnormal heart rhythm episode (linked with an increased risk of sudden cardiac arrest) compared to those who had no scarring, the findings suggest. 

The study involved 106 healthy male endurance athletes, aged over 50, without symptoms or a diagnosis of cardiovascular disease. All were competitive cyclists or triathletes, who had been exercising for 10 or more hours every week for at least 15 years.

At the beginning of the study, all participants had an MRI scan to identify any scarring, and an implantable loop recorder fitted to record their heart rhythm.  

Scans revealed that that nearly half had scarring in their hearts, most commonly in the bottom of their left ventricle. Athletes with scarring were on average slightly older (61.8 years compared with 57.0 years). 

This was more than four times higher when compared to a group of non-athletes, matched for age and sex, who took part in up to three hours of exercise per week.

During the two-year study, more than one in five of the endurance athletes had at least one episode of ventricular tachycardia. Of these, more than three quarters (78 per cent) had evidence of scarring in their hearts on MRI scans. 

Three suffered one or more episodes of sustained (longer than 30 seconds) ventricular tachycardia which in certain circumstances can be life threatening. All were previously identified to have scarring in their hearts. 

President of British Cycling and world governing body Union Cycliste Internationale,  Brian Cookson, 74 (pictured), was one of those involved in the trial.

In May 2024, while training at Manchester Velodrome, Cookson’s sports watch revealed his heart rate was a record 238bpm and took an estimated 15 minutes to return to normal.

As part of the trial, Cookson had been fitted with an implantable loop recorder, a small device about half the size of a biro pen placed under the skin of his chest to record his heart rhythm.

He was warned by the research team that he had suffered an episode of ventricular tachycardia – an abnormally fast heartbeat where the heart’s ventricles contract too quickly and fail to pump blood effectively.

As ventricular tachycardia can lead to cardiac arrest, Cookson was fitted with an implantable cardioverter defibrillator (ICD) to shock his heart if it went into abnormal rhythm. 

“I’m so grateful to have been part of this study. It might well have saved my life. Without it, I might have carried on pushing myself until something more serious happened. We’ve been able to take action to manage my condition, and I’m still cycling regularly,” he commented. 

Dr Peter Swoboda, associate professor in cardiology and consultant cardiologist at the University of Leeds who led the study, stressed the findings should not deter people from regular exercise.

He added it had focused on a very select group, and not all athletes involved had signs of scarring. 

Swoboda added: “In our study, the athletes who experienced dangerous heart rhythms often had symptoms first. I’d encourage anyone who experiences blackouts, dizziness, chest pain or breathlessness, whether during sport or at rest, to speak to their doctor and get it checked out.  

“These results shouldn’t put people off regular exercise. Our study focused on a very select group, and not all the athletes involved were found to have scarring in their hearts.” 

Research is now focusing on female endurance athletes, to determine whether they also experience scarring and increased risk of abnormal heart rhythms. 

Dr Sonya Babu-Narayan, clinical director at the British Heart Foundation and consultant cardiologist, said: “There’s no doubt that exercise is good for our hearts. But in some veteran male athletes, this early research suggests that intense exercise over many years may have affected their heart health.  

“More research in veteran endurance athletes – both in men and women – will be needed to identify the small number of people who have the kind of heart scarring, together with other risk factors, that mean their life could be saved by having an implantable defibrillator.”