The largest prospective study of athletes ever
The largest prospective study in the world is happening right here on our doorstep (that is, if you live in Melbourne) – and it is focussed on athletes and their hearts. In a recent article that appeared in Cycling Tips, Dr Andre La Gerche from the Baker Heart and Diabetic Institute provides some interesting perspectives on the investigations, which will see researchers follow athletes over a long period of time. This story has special significance for me. A synopsis follows:
Many of you would be familiar with the notion of ‘athlete’s heart’, which is essentially an enlarged heart attributed to excessive training, often associated with elite endurance athletes. But, did you know that one of the undesirable effects of a large heart is the increased tendency to experience irregular heart rhythms?
Atrial fibrillation (AF)
The most common heart rhythm disorder in people of middle-age and older is ‘atrial fibrillation’ – a random firing of electrical signals from the upper chambers of the heart that causes a rapid and irregular heartbeat.
Some people with AF do not experience symptoms, and are completely unaware that they have AF. Others may suffer symptoms, including the uncomfortable sense of an irregular heart rhythm, fatigue or breathlessness.
Is too much exercise actually bad for you?
Research has shown that there is a higher rate of AF amongst endurance athletes compared with non-athletic individuals (although, interestingly, this excess in AF has not been observed in female athletes). This begs the controversial question:
‘Can too much exercise start to cancel out the health benefits of moderate exercise?’
Despite the growing trend that warns of the dangers of over-exercising, there is a paucity of evidence to know whether the heart changes seen in athletes might cause other potentially dangerous arrhythmias. Furthermore, as La Gerche emphasises, we do not have reliable predictive measures for determining which athletes might develop problems down the track.
Food for thought … !
As someone with an existing heart muscle disorder, viz. hypertrophic cardiomyopathy, I’m obviously very interested in this research. I have a thickening in my ventricular wall which means that I am already predisposed to having irregular heart rhythms, notably non-sustained ventricular tachycardia (VT). After my diagnosis at the age of 35, I decided to take up endurance training where I could keep my heart rate down within relatively ‘safe limits’. I am very careful to keep myself in check on the odd occasion when I might run in shorter and sharper races, and I am also cautious when climbing hills. I must be careful not to get my heart rate too high, as this might trigger a potentially dangerous heart rhythm or cause my ICD/internal defribillator to discharge unnecessarily.
Hence, the article by La Gerche raises questions for me. If ‘endurance’ training has its own set of unique side effects, then someone like me with hypertrophic cardiomyopathy might not actually be taking the ‘safe course’ by concentrating on endurance, even if that accommodates a lower heart rate for training and competitions (Of course, there are many who would recommend the safest bet for me is to stay idle and not exert myself, at all – somehow that falls outside my scope of comprehension.)
If there should be any causative relationship between endurance and heart arrhythmias, does this mean that my already irregular heart rhythm is likely to become especially more unpredictable should I persist with endurance training over time? Am I more susceptible than the average Joe? Definitely, food for thought … !
The Pro@Heart Study
Researchers in Australia, Belgium and France are collaborating together to investigate the association between endurance sport and arrhythmias. They will comprehensively assess young elite athletes and follow their health and performance for many years.
Some of you might have heard of the large scale prospective studies of the general population that have contributed to our understanding of the health effects of cholesterol, blood pressure and other lifestyle factors – notably, the Framingham Heart Study (New England, USA) and the Busselton Health Study (Western Australia).
There have not been studies of this nature and scale in athletes. The Pro@Heart Study aims to be the largest propective study in the world.
Watch this space! This body of work will surely yield the most comprehensive picture of athletes’ hearts that we have to date. I know that I certainly will be following this one over time.
Author: Kara Gilbert @ KMG Communications