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Too much high-intensity exercise can be bad for your heart, study says

Middle-aged white men are at a higher risk of developing plaque in their arteries if they do intense exercises, researchers say.
Middle-aged white men are at a higher risk of developing plaque in their arteries if they do intense exercises, researchers say. Getty Images

There’s such a thing as too much exercise, a new study suggests – at least for middle-aged white men.

According to researchers at the University of Illinois at Chicago and Kaiser Permanente, white men in particular who exercise at high intensities are 86 per cent more likely to develop plaque buildup in their arteries than those who exercise at low intensities.

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The link was not seen in black men, however.

To find this out, researchers studied the physical activity trajectories of 3,175 white and black participants in the  Coronary Artery Risk Development in Young Adults (CARDIA) study with baseline ages of 18 to 30, and looked at the presence of coronary artery calcification (CAC) in participants.

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(CAC is the buildup of calcium and plaque in the arteries of the heart. It can be a significant warning sign of impending heart disease, the study explains.)

Those who took part in the study self-reported their physical activity during at least three of eight followup examinations over a 25-year period from 1985 to 2011.

Participants were put into three categories based on their physical activity patterns. The first consisted of those who exercise below the U.S. national guidelines (less than 150 minutes a week); the second were those who met the national guidelines for exercise (150 minutes a week); and group three, which included those who exercised three times above the national guidelines (more than 450 minutes a week).

“We expected to see the higher levels of physical activity over time would be associated with lower levels of CAC,” Deepika Laddu, assistant professor of physical therapy in the UIC College of Applied Health Sciences, said in a statement.

However, Laddu and her team found the opposite was true.

In fact, those who exercised the most (Group 3) were found to be 27 per cent more likely than those who exercised the least (Group 1) to develop CAC by middle age.

After accounting for age and race, the team was able to find that white men were at the highest risk. There was a similar trend for white women, the study says, but it was not statistically significant.

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“Because the study results show a significantly different level of risk between black and white participants based on long-term exercise trajectories, the data provides rationale for further investigation, especially by race, into the other biological mechanisms for CAC risk in people with very high levels of physical activity,” Laddu said.

The study was published in Mayo Clinic Proceedings.

Other studies in the past have also found a link between high-intensity workouts and the impacts on heart health.

A 2014 study published in BMJ found that engaging in too much prolonged high-intensity exercise may actually increase the risk of death from a heart attack or stroke in people who already suffer from heart disease.

Researchers found that those who did the most strenuous daily exercise were more than twice as likely to die of a heart attack or stroke.

Another study also found that young men who engaged in endurance exercise for more than five hours a week may up their risk of developing an irregular heart beat later in life by 19 per cent compared to men who only did less than one hour a week.

However, short bouts of high-intensity workouts were found to be beneficial for those who suffer from Type 2 diabetes.

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According to the American Heart Association, patients with Type 2 diabetes who engaged in three 10-minute high-intensity workouts for five days of the week improved cholesterol, blood sugar and weight.