Exercise: Can There Be Too Much of a Good Thing?

By Larry Husten

Two studies in the journal Heart suggest that health benefits may be curtailed in people who exercise very frequently or very intensely.

In the first study, researchers analyzed data from exercise questionnaires and hospital records of nearly 45,000 Swedish men. Men who exercised intensively more than 5 hours a week at the age of 30 were more likely to develop atrial fibrillation (AF) than men who exercised less than 1 hour a week. Their risk was even higher if they subsequently quit exercising later in life.

In the second study, researchers followed more than 1000 patients with coronary heart disease. Overall, patients who exercised strenuously 2–4 days a week had the lowest risk for death and cardiovascular events. But there was an increase in risk in both the group who rarely exercised and in those who exercised every day.

Editorialists speculate that intensive exercise may have a proinflammatory effect that may be especially harmful in some people with atherosclerotic disease.

Adapted from CardioExchange.