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Cardiac Problems in Endurance Athletes
We all know that exercise is good for your heart. It decreases blood pressure, lowers blood cholesterol, maintains healthy body weight, and diminishes your risk of developing chronic diseases including diabetes mellitus. But are there instances when exercise – specifically, endurance exercise such as distance running – may be harmful? I grit my teeth as I painfully type the word “Yes”… But, yes. Even if your brain and your spirit crave that morning glide through the heathery foothills, there may be a few things to think about before pronouncing to the world that THIS is THE BEST way to maintain a happy heart.
- The scary stuff. These are the unpredictable, and often inherited, problems that result in sudden death. It can include structural problems with the muscle of the heart itself (e.g., hypertrophic cardiomyopathy), valve problems (e.g., aortic stenosis), electrical problems resulting in abnormal coordination of the pumping action (e.g., Wolff-Parkinson-White syndrome, long QT syndrome), or plumbing problems where the blood supply does not get to the muscle normally, creating an oxygen deficit (known as congenital anomalies of the coronary arteries). Fortunately, they are uncommon. But for those that do have these problems, endurance exercise is more or less forbidden.
- Athlete’s heart. It is well recognized that the heart muscle experiences structural changes with exercise, commonly observed as a global thickening of the main pumping chamber. (Not surprising, considering that structural changes with every other muscle in your body occur with exercise as well.) Historically, this has not been considered a bad thing, and has been shown to reverse after training is discontinued. However, there has recently been a body of literature that suggests some of this remodeling effect observed in high level athletes – which specifically includes enlargement of the one of the upper chambers of the heart – may serve as a nidus for an annoying, though usually not life-threatening, rhythm problem known at atrial fibrillation. The data are not perfect here, but multiple studies from several countries have replicated this association, and the increased risk appears to be pretty substantial (2-10x increased risk).
- Is this You, you may ask? Well, the answer is, we just don’t know. “High level” has had multiple definitions: 3 hours or more per week of intense training, 1500 lifetime hours of endurance exercise, being within the highest category of a large population polled, or simply just participating in a couple of long distance events (marathons, the Tour de France, cross-country ski races… Who cares, those crazy endurance people are all alike anyway, right?!). To say the least, the optimal dosing of frequency and intensity of endurance training has yet to be determined. And to add insult to injury… We don’t know the risk among women, as they have been underrepresented in these studies.
- Are there other risks? The main risk with atrial fibrillation includes stroke. However, most athletes have few risk factors that make this a major concern. Talk to your doctor.
- Gimme some good news?!!. Low to moderate amounts of exercise show NO such association with atrial fibrillation. Among those afflicted, detraining may help – a few weeks off, then a couple of 3-4 mi runs per week may be tolerated. Lastly, there are effective medical therapies also available.
- When to worry/seek help. If you experience chest discomfort, unusual breathing trouble, sudden exercise intolerance, and/or lightheadedness with exercise, seek immediate help. If you lose consciousness for unclear reasons, seek help. If you experience funny “skipping” sensations that last for more than a few seconds, especially if they are associated with lightheadedness, seek help. Lastly, if any of your family members has a problem listed in #1 above, you should also be seen by a Cardiologist for screening.
Stay safe and Happy Trails, Betties!
