The plain answer is yes. The more nuanced answer is, it depends. With 80% of people being physically inactive, exercise is one thing almost all of us should get more of. Despite this, there are plenty of articles, studies and anecdotes suggesting yes, you can get too much exercise.
Legend has it Philippides, a Greek messenger, ran 25 miles from Marathon to Athens circa 490 BC, delivered his message and promptly died. He had exerted himself to complete exhaustion. Did he die from too much exercise? The events surrounding his run aren’t fully clear and some suggest he ran 600 miles in the days before. And in the last century, millions have safely run marathons and ultramarathons.
The notion you can get too much exercise gained popularity in the 1980s when running advocate Jim Fixx died of a heart attack while running. He started the running craze and wrote five books including The Complete Book of Running. A common reaction was if someone who regularly trains and can still die exercising, what chance does everyone else have?
What gets lost, is Mr. Fixx had a strong family history of heart disease. His father had a heart attack at the age of 35 and died at 43. Mr. Fixx was a former heavy smoker and the autopsy revealed he had blockages in his heart arteries. But since he was running alone when he died, no one knows exactly what happened, whether he experienced symptoms or how hard he was running. This only added to the mystique around the safety of exercise.
Exercise Increases Risk (albeit very small)
When we exercise, our heart beats faster and works harder. This added stress is good for the heart because like any other muscle, when you work out it gets stronger. But there’s also a greater chance (albeit very small) of having a heart attack or sudden cardiac arrest. It’s about 1 death in 36.5 million hours of exercise compared to 1 in 59.4 million hours of sitting. To put this into perspective, if you live to 80 years, that’s only 700 800 hours.
Additionally, regular exercise actually lowers this risk even more. As you get better in shape, your body becomes more efficient. It’s the person who doesn’t exercise, and then exerts his/herself, who’s in the most danger. And that exertion doesn’t need to be a planned exercise, often it’s something such as snow shovelling or other unplanned activity.
Despite this very small increased risk, exercise is a proven treatment for people who’ve had a heart attack. These cardiac rehabilitation programs, in which patients exercise multiple times per week, have been shown to reduce the chance of another heart attack and early death.
Can too much exercise give you heart disease?
There are situations when too much exercise could be bad for you. Following an ultramarathon (160 km run), runners had changes in their heart’s function and physiology. These changes would be considered as damage to the heart if found in a non-exerciser. However, it’s not clear if these changes are a problem or a favourable adaptation to exercise.
The environment one is exercising in also needs to be considered. Activity in extreme heat or cold, places an added stress on the body. In hot weather, your body needs to not only keep your muscles going, but also works to cool your body. If your internal temperature gets too hot, it can lead to heat exhaustion. When it’s cold, your body takes longer to warm-up. This poses a problem with sudden and unplanned exertion, such as snow shovelling, which can increase one’s chances for a heart attack. However, this may be due to the condition of the person shovelling snow as opposed to the activity itself. For many people, snow shovelling may be the most strenuous activity they usually do. For people who regularly exercise, snow shovelling is less likely to be a problem.
There are also conflicting reports on people who exercise a lot. For example, studies comparing athletes to non-athletes show a greater risk for atrial fibrillation. In addition, endurance cross-country skiers also had a higher risk. However, regular exercise at the level of the recommended guidelines (150 min/wk of moderate/vigorous activity) or more, suggests a lower risk for atrial fibrillation. Exercise is also recommended for people who have atrial fibrillation.
Similarly, some studies suggest too much exercise may lead to atherosclerosis. This study found that men who exercised three times more than the physical activity guidelines, had greater coronary artery calcification (CAC), a potential marker of heart disease. However, our work, and that of others, show even high volumes of exercise are associated with lower risk for heart complications and early death. Other studies have shown the atherosclerotic plaques in athletes tend to be of the more stable type and less likely to lead to a heart attack compared to the plaques found in inactive people.
Overtraining
But not all of the possible negatives of too much exercise are related to dramatic outcomes such as heart problems and death. Pushing oneself to do a lot of exercise over the course of weeks and months may lead to poor performance and possible injury. This is what’s called overtraining. It’s usually due to continual hard exercise sessions and/or lack of proper recovery time.
Some early signs of overtraining include ongoing muscle soreness, irritability and poor quality of sleep. And you don’t have to be an elite athlete to succumb to overtraining. As we age it takes longer to recover from hard exercise sessions and if one applies how they trained in their 20s to being in their 50s and older, it’s unlikely to provide enough recovery time. If you do feel you’re overtraining, take a step back to rest, look to see if you’re meeting your nutritional needs and slowly return to your desired levels.
For most of us, concerns of doing too much exercise don’t apply. The overwhelming evidence suggests regular exercise is beneficial in preventing heart and other diseases, as well as increasing lifespan. While there may be adverse effects in people who do extremely high amounts of strenuous exercise, the findings are unclear. We should take pause and recognize the main problem in our society is that people don’t do enough exercise, not that they do too much.
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