Can too much sport be bad for your heart?

  • Exercise is good for the heart and body, but excess can have negative consequences, such as atrial fibrillation and a higher risk of stroke.
  • Two research studies have shown that highly trained athletes can develop heart problems, indicating that overtraining may carry more risks than benefits.
  • It is not advisable to stop exercising, but it is important to pay attention to the body’s signals and consult a specialist if you experience symptoms such as palpitations, sudden shortness of breath, or deterioration in performance.


Is there a truer maxim than “Too much is too much”? Or “Everything has a limit,” even things that are good for us? Looking at it from another point of view, every excess never comes alone and sometimes brings with it unpleasant companions. In short, it is not necessarily the case that if one thing is good for you, an overdose of the same thing will do you very well; on the contrary: a glass of water is always good for you, but that does not mean that drinking 10 liters of water at one time will do you very well. Quite the opposite.

On the heels of this idea, two researches sought to explain-under the understanding that exercise IS VERY GOOD for your heart and body-whether overtraining and living an active life too “over the edge” could have negative rather than positive effects.

But let’s start with the real protagonist of this story, and that is our friend: the heart.

What exercise does to the heart

Let’s start with the basics: the heart is a muscle and, as such, can be trained and made stronger through exercise. When we train and, in proportion to the effort we are putting in, require it to put in equally adequate effort, we are also making it stronger, just like the muscles in our legs and arms.
The heart also changes its ability to pump blood: the more we require of it peripheral tissues (i.e., muscles), the more it adapts by increasing the volume of its cavities, i.e., atria and ventricles). As in everything, however, there is a limit, and two researches sought to understand whether prolonged exertion and relentless training as well as very strenuous competitions eventually require us to pay a price, and they ask just that of our most important muscle/organ.

Let’s remind that this research does not question the assumption that remains true and verified, which is that training-especially if it is continuous and prolonged-brings only benefits. Indeed, it remains true that people who are sedentary or engage in very little if any physical activity are much more likely to develop heart problems than those who exercise. And this is for a very simple reason: as a muscle, the heart is “trainable,” and an underused and neglected muscle ends up losing elasticity, strength and tone, to the most tragic outcomes.
What they possibly show is, if anything, that overtraining (like all excesses) can have more negative consequences than positive ones.

The research

That said, what did the research show? One is from 2019 and was conducted by Swedish scientists who collected the medical records of as many as 208,654 participants in the Vasaloppet, a series of grueling cross-country ski races, and then compared them with those of 527,448 people (men and women) who had not participated in the race.
The data showed that the hearts of some of them-despite being highly trained (or perhaps because of it)-were more likely to develop atrial fibrillation, which is an irregular heartbeat that can lead to blood clots and a higher risk of stroke.

The other research, published in the Clinical Journal of Sports Medicine, concerns a data collection done in 2021 on 942 middle-aged endurance athletes of both sexes who had participated in competitions. About 20% of these had been diagnosed with episodes of atrial fibrillation, and 3% had had a stroke. Most of them were men, and in a significant number were swimmers.

There is no explanation for why the phenomenon occurs more often among men, let alone why it also affects swimmers (implicating triathletes in this), but one of the researchers-Susil Pallikadavath-points out that the figure may be “tainted” by the fact that the research was mainly attended by athletes who had experienced heart complications of some kind. In other words, it is likely that the percentage figure would have been lower if the research had evaluated a larger sample, including normal, non-supertrained people.

Is it better to stop training?

Absolutely not, as Meagan Wasfy of Boston’s Mass General Brigham Hospital specifies: there is no doubt that moderate to intense training only in specific sessions is only good for you, including reducing the chance of incurring atrial fibrillation and protecting against plaque formation in the arteries, by far one of the deadliest heart diseases.

What we need to do is to pay attention to certain signals from our body and also to the data reported by the sportswatches we use (very useful in these cases):
– If you have sudden palpitations
– If you get out of breath during training (and this had never happened).
– If your performance deteriorates without any warning
– If your sportwatch reports spikes in your heart rate

then it’s best to slow down, stop, and go see a specialist as soon as possible.

All of the above-insistently emphasize the researchers-does not mean that it is wise to stop exercising; on the contrary: the benefits of an active life are beyond question.
What needs to be kept in check is, as always, overcompetitiveness and overtraining. Which, we know, for some people can become a real addiction.
However, if your heart is involved, it is better to think about it a thousand times before asking it once again for an effort that will only serve to make you feel good mentally, gratify you and pump your ego up. At the expense of your most important organ.

(via The Washington Post)


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