Is too much physical activity bad for the heart?

New research has highlighted that there may be such a thing as too much exercise. While regular physical activity has long been known to bring numerous health benefits, scientists are beginning to recognize that an excess of intense physical activity may bring its own health risks.

Is exercise in moderation better?

A new study has concluded that too much exercise may be bad for your heart. The results are surprising, given that inactivity is linked with health risks such as obesity, heart disease, type 2 diabetes and a multitude of chronic illnesses.

Previous research into the impact of exercise has almost exclusively focused on how much, or how little, is required to benefit health. Now scientists are looking at it the other way around; they are exploring the long-term impact of intense exercise on the body.

The results are suggesting that there may be an optimal level of in-between inactivity and intense activity, with both too much and too little being associated with different health risks.

Potential risks of intense exercise

Researchers in the US conducted a study over a period of 25 years that looked into the development of subclinical coronary artery disease (CAC) in relation to physical activity trajectories.

The results showed that those who had engaged in physical activity that was significantly over the national physical activity guidelines were at an increased risk of developing CAC by the time they reached middle age.

The study looked at 3,200 people over the course of 25 years, beginning testing at the time they were young adults. Using CT scans the researchers measured calcium-containing plaques which acted as a predictor of CAC. The participants were split into three groups relating to their level of physical activity, and the risk of CAC related to these groups was investigated.

The results showed that people who engage in physical activity that exceeds the recommended amount by at least three times were at an increased risk of developing CAC. This would be three times over the recommended 150 minutes of weekly moderate-intensity activity or 75 minutes of weekly vigorous-intensity activity.

The study also found that the risks related to extreme exercise were more prominent in white participants, finding that white participants in the intense exercise group were at an 80% higher risk of developing CAC. The effects were also greater for white men than white women.

Those who exercised less were not safe from health risks. This group was at an increased risk of developing high blood pressure and type 2 diabetes by middle age, demonstrating that both too much and too little exercise has its health risks, suggesting that a moderate amount is optimal.

Strenuous activity at work poses risk to health

In another study, researchers in Paris, France, studied 10,000 participants over a 10 year period. They investigated the impact of physical activity on health. They found that high intensity sporting physical activity was associated with health benefits and that it was physical activity at work that was the kind of activity that posed a threat to long-term health.

People whose jobs required regular exertion, such as routinely lifting heavy loads, were at a greater risk of developing abnormal neural baroreflex and greater arterial stiffness, two factors which have a negative impact on cardiovascular health. They suggest that chronic, strenuous activity at work may pose a threat to health.

Take-home message

The impact of engaging in regular, intense physical activity over time is still not fully understood, as the research in this field is still limited. However, early indications suggest that excessive exercise (three times the recommended amount) is associated with an increased risk of developing CAC.

While other studies have found that high intensity sporting physical activity is related to health benefits, the take-home message is that there is likely a limit to how much exercise is good for you. This has implications for athletes, whose long-term health should be considered in light of these findings.

Is physical activity always good for the heart? Eurekalert. Available at: https://www.eurekalert.org/pub_releases/2019-11/ind-ip103119.php.