Exercise is good for the heart, but studies have suggested that people who participate in long-term endurance sport could run the risk of 'scarring' the organ over time. In rare cases overworking the heart can lead to an abnormal heart rhythm or even sudden cardiac arrest.
The British Heart Foundation (BHF) said a study involving male athletes aged over 50 found that around half of the participants had developed scarring on their heart to some extent. It is thought this could be caused by their high levels of exercise as during endurance sports like long-distance running and cycling the heart must work even harder to pump blood. However, it is still unclear how scarring has developed.
Experts stress that just because a person may have heart scarring, it doesn't always mean they will then have a cardiac event, and most will experience no symptoms at all. People will only usually discover they have heart scarring when they have an MRI scan, for example when they are suspected of having a heart condition.
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Glyn Jones was 55 when he suddenly collapsed while competing at the Tenby Long Course Weekend in 2019. It was discovered that Glyn, who grew up in Brecon, had been living with coronary heart disease which had been undiagnosed. Sadly, he later died in hospital.
His brother Gethin Davies-Jones, who lives near Caerphilly, is now the same age as Glyn as is similarly into his fitness. "Cycling is a huge passion of mine - I enjoy competitive time trialling and I'm a beginner triathlete. The sport is great for my mental health and since taking it up I've been able to lose 12kg in weight. However, when I get out on my bike there is always the worry in the back of my mind that what happened to my brother could happen to me," admitted Gethin, 55, who also lost his mum to a sudden cardiac arrest when she was in her late 40s.
"Losing family members when they were of a young age had a huge impact on me. There are so many conversations and memories I now won't be able to have with my brother and mum, and their experiences have put my own mortality sharply into focus."
New research by the BHF will monitor the heartbeats of 106 athletes over two years to measure how endurance exercise impacts their heart. The £320,000 project at the University of Leeds will see the athletes fitted with a small implantable monitor, around half the size of a biro pen, under the skin on their chests.
The monitor will measure every single one of their heartbeats over two years, particularly allowing researchers to assess the athletes' heart rate during and after exercise. Previously, this measurement has been carried out using sensor stickers and fitness trackers which have not always been accurate. The participants will also undergo MRI scans which will look for signs of scarring and assess heart function - alongside blood and fitness tests.
Overall, the research will aim to understand if heart scarring in athletes is linked to abnormal heart rhythms, and could inform future research around ways to avoid or reduce heart damage in endurance sports. The research is now underway at the Advanced Imaging Centre at Leeds Teaching Hospitals NHS Trust and is being led by Dr Peter Swoboda, senior lecturer at Leeds University.
Gethin, who is taking part in the study, added: "That's why my interest in this study is so immediate and deep as it will help me understand more about my own heart health. It's great that the British Heart Foundation is funding this research as it could really benefit athletes like me."
Dr Swoboda said: "Exercise is good for the heart, but studies have suggested that people who participate in long term endurance sport could lose the health benefits of exercise - and in some cases, may even be damaging their hearts over time.
"For an athlete, an abnormal heart rhythm can often result in the end of their career, and we are all familiar of the devastating but rare occurrence of sudden death during sport.
"With the implantable monitors set to detect billions of heartbeats, we are going to learn so much through this study, including whether heart scarring is linked to irregular heart rhythms. This could help identify who is most at risk, and some of the lessons we learn could be applied to younger athletes, too."
Dr Subreena Simrick, senior research advisor at the BHF, added: "Physical activity can reduce the risk of heart and circulatory diseases, helping to control your weight and reduce blood pressure and cholesterol levels.
"This research is looking at how endurance exercise impacts the heart, and whether heart scarring found in some athletes is a factor that leads to potentially dangerous irregular heartbeats. If it is, then this project could pave the way for further research into potential treatments and preventions, allowing athletes of all ages to participate in sport as safely as possible.
"For more than 60 years, the public's generosity has funded BHF research that has turned ideas that once seemed like 'science fiction' into treatments and cures that save lives every day. We urgently need the public’s support to keep our life saving research going, and to discover the treatments and cures of the future."
