Can You Exercise Too Much?

The American College of Cardiology's Sports and Exercise Cardiology Leadership Council writes that "small amounts of physical activity, including standing, are associated with a lower risk of cardiovascular disease, but more exercise leads to an even greater reduction in risk of death from cardiovascular disease." (J Am Coll Cardiol, 2016;67(3):316-329). You are better off exercising than not exercising, and there is no good evidence to support any upper limit to the benefits of exercise.

However, a letter in the Journal of the American Medical Association ((April 19, 2016;315(15):1658) expresses concern that some people may reduce their exercising because of a few studies that seem to show that:

• intense exercise does not prolong life more than casual exercise does, and

• people with heart damage may be harmed by too much intense exercise. The studies that prompted this letter include:

Studies on Healthy People

• The Copenhagen Study, over 12 years, showed that the death rate for casual and moderate joggers was much lower compared to non-joggers, but there was no additional life extension for high-intensity joggers (J Am Coll Cardiol, 2015;65(5):411-419). However, there were only 36 intense joggers with two deaths out of 1,098 joggers and 3950 non-joggers, so I believe that the honest conclusion is that they did not have sufficient data on intense exercisers to make any comparison.

• The Million Women Study, over nine years, reported that the rate of strokes was the same for vigorous exercisers as for those who did not exercise, whereas those exercising two to three times a week were less likely to suffer strokes (Circulation, 2015;131(8):721-729). However, this study did not correct for differences such as smoking habits or socioeconomic class.

Studies on Heart Attack Patients

• The National Walkers’ and Runners’ Health Studies, over 10 years, showed that heart attack victims who exercised were less likely to die than those who did not exercise as long as they ran less than four miles per day or walked less than eight miles per day (Mayo Clin Proc, 2014;89(9):1187-1194).

• The German KAROLA study, over 8.1 years, showed that patients with coronary heart disease who exercised two to four times a week had a much lower death rate than those who did not exercise. However, the strenuous exercisers had a higher death rate than those who exercised two to four times a week (Heart, 2014;100(13):1043-1049).

A heart attack occurs when the blood supply to a part of the heart muscle has suddenly been shut off completely and that part of the heart muscle dies. Both of these studies suggest that people who have already had some dead heart muscle from a previous heart attack may be at increased risk for irregular heartbeats from long and intense exercise. However, nobody has shown that healthy people with undamaged hearts should limit how hard or how long they exercise.

Exercise is Medicine Dr. Paul Thompson, who has run 29 Boston Marathons over the past four decades, writes that "there is no known upper limit for moderate-intensity physical activity in healthy individuals, but doses more than 100 minutes a day do not appear to be associated with additional reductions in mortality rates. No dose of vigorous physical activity is associated with higher mortality rates than physical inactivity. Physical activity is one of the best modifiable factors for the prevention of noncommunicable diseases and mortality, so it is important for clinicians to keep emphasizing that exercise is medicine." (JAMA, November 10, 2015;314(18):1915-1916). Virtually all of the studies on elite athletes show that those who exercise to extremes live longer than their less-active countrymen (Mayo Clin Proc, 2014 Sep;89(9):1195-200).

My Recommendations Most studies on exercise and longevity show that exercisers are far less likely to suffer heart attacks, diabetes, certain cancers, dementia and premature death. If you do not compete and have a healthy heart, the odds are high that the benefits of any amount of exercise far exceed the chances that you will harm yourself.

If you are an older healthy person who competes in sports, I believe that you are better off exercising intensely rather than spending many hours at a more casual pace. Having purpose and goals is healthful and emotionally rewarding. Everyone should continue to have physical performance goals as he or she ages.

How This 83-Year-Old Exercises On Tuesdays, Thursdays and Saturdays, I ride my bike in a group for more than 30 miles at close to my fastest pace. On the other four days of the week, I do 50-pedal-stroke intervals almost as fast as I can ride, interspersed with slower riding until I recover. When my legs start to stiffen, I stop the workout. I can usually get in 20 to 30 intervals in a 40-minute workout. My legs are always sore in the morning. If they do not recover and feel fresh after a five-to-10-minute warmup, I take the day off. I also stop my workout if I feel pain in one area that worsens as I continue to exercise. 

Checked 5/2/19

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