Overdoing the super popular HIIT workouts can be disastrous for your health

If you work out, you know all of the health benefits that come with getting your sweat on a few times a week. However, according to a recent scientific statement from Oakland University, high-intensity exercises may increase the risk of several heart conditions, including cardiac arrest.

“Vigorous physical activity, particularly when performed by unfit individuals, can acutely increase the risk of sudden cardiac death and acute myocardial infarction in susceptible people,” researchers reported. 

The statement was published in the journal Circulation after a review of over 300 studies revealed the risks associated with extreme endurance exercises. However, the risk seems to be limited and is primarily a concern for individuals who are not accustomed to high-intensity workouts. In fact, several scientists voiced that the benefits of regular exercise far outweigh the risks. 

“Moderate exercise is still the best prescription for good physical and mental health – and competitive athletes shouldn’t give up their training schedule just yet,” cardiologist Tamanna Singh, MD, said. “While there is evidence that prolonged strenuous exercise can increase risk of atrial fibrillation, the long-term risk of this is small compared to inactivity.”

In fact, chair of the writing committee for the new Scientific Statement, Barry A. Franklin, Ph.D., said that moderation is really key here. 

“Exercise is medicine, and there is no question that moderate to vigorous physical activity is beneficial to overall cardiovascular health,” Franklin said. “However, like medicine, it is possible to underdose and overdose on exercise – more is not always better and can lead to cardiac events, particularly when performed by inactive, unfit, individuals with known or undiagnosed heart disease. More people are running marathons, participating in triathlons and doing high-intensity interval training. The purpose of this statement is to put the benefits and risks of these vigorous exercise programs in perspective.”

The study did also reveal that those who are physically active on a regular basis had a 50% lower risk of heart attack or cardiac death. And even for those who participate in high-intensity workouts, the risk was relatively low. However, the writing team recommended a slow and steady increase when it comes to exercise intensity.

Men also seem to be more at risk here. The study revealed that women were 3.5 times less likely to experience a cardiac event than men when it came to strenuous exercise. 

This also isn’t the first study to reveal heart risks with long-term endurance exercise. 

In 2013, a team of Swedish researchers conducted a study of more than 52,000 skiers. Those who had completed the most races or had the fastest times had a higher risk of heart arrhythmias.

In 2019, the same group published a similar study, this time of more than 208,000 skiers. Again, the results showed that atrial fibrillation risk was increased for the fastest and most frequent skiers. Interestingly, however, these results only held true for men. Female skiers actually experienced the opposite effect, with a lower risk of atrial fibrillation versus non-skiers. 

According to an article published by The Washington Post on the study, this may be due to swelling or scarring that occurs when the heart is stretched during long-term endurance exercise. 

“We know for sure that chronic, extreme exercise increases atrial fibrillation risk by about 500 percent, maybe as much as 800 percent,” James O’Keefe, a cardiologist in Kansas City, Mo., said. “I’ve been an exercise addict my whole life… There’s a subconscious logic that says if some is good, more is better, but that is absolutely wrong when it comes to exercise.”

Dr. Singh agreed. However, she said this still is not much of a concern for most people. 

“Extreme, long-term endurance exercise puts equally extreme demands on the cardiovascular system,” she said. “[However], despite the concern about extreme exercise, there is not much reason for the average person to worry. Exercising is far better than being inactive.”

For those who want to be more active, the American Heart Association recommends a minimum of 150 minutes of moderate physical activity per week.

“It is important to start exercising – but go slow, even if you were an athlete in high school,” Franklin said.

In any case, you should always consult your doctor before engaging in any strenuous activity or beginning a new workout program. Especially for those who have any preexisting conditions or are currently inactive/sedentary, it’s important to make sure you are exercising safely.