Doctor’s Tip: Is there such a thing as too much exercise? |

Doctor’s Tip: Is there such a thing as too much exercise?

Dr. Greg Feinsinger

The evidence is clear that regular exercise has many health benefits. It decreases the risk of heart attacks, strokes, Type 2 diabetes, osteoporosis and many forms of cancer. It lowers weight and blood pressure, helps with sleep, and relieves stress and depression. People who exercise live longer and have better quality of life as they age.

Most authorities recommend moderate-intensity aerobic exercise such as brisk walking (4 miles per hour) for at least 30 minutes a day, but only a minority of Americans achieve this. Additional benefit occurs with 60 minutes a day and even more with 90 minutes. I tell patients to walk at least 30 minutes a day, fast enough so that they could talk but not sing. People age 40 and older need to also do strength training (e.g. resistance bands, light weights, kettlebell) for 20 minutes twice a week on non-consecutive days. The reason for this is that loss of strength starts at around 40, which contributes to aging. If you exercise but sit at a desk the rest of the day, that undoes the benefit of exercise, so use a standup desk and/or walk around every 30 minutes.

Beyond about 90 minutes a day of moderate exercise or lesser amounts of intense exercise, the risks may outweigh the benefits, and in this valley we definitely see overexercisers. (Full disclosure: I include myself in this group.) These people have convinced themselves that if some exercise is good, more must be better, and are either addicted to exercise (the endorphin high) or are competitive enough that they push themselves beyond what is health-promoting.

How to define too much exercise varies with the exerciser, but as a Supreme Court justice once said about obscenity, “I know it when I see it.”

An excellent book on this subject, published earlier this year, is “The Haywire Heart, how too much exercise can kill you, and what you can do to protect your heart.” The authors are John Mandrola, M.D., a cardiac electrophysiologist (a cardiologist who subspecializes in problems of the electrical conduction system of the heart); Chris Case, editor of VeloNews; and Lennard Zinn who custom makes bicycles in Boulder. All three are elite athletes, and Zinn has a personal history of a heart arrhythmia that he attributes to overexercise.

The most common cause of death in the U.S. is heart attacks, caused by rupture of atherosclerotic plaque in a coronary (heart) artery. There’s evidence that in general heavy exercisers develop more plaque than non-exercisers, but their plaque tends to be calcified and more stable. So far there is no evidence that these athletes are at increased risk for heart attacks (non-athletic people with high calcium scores are).

Prolonged/intense exercise has been shown to cause elevation of cardiac enzymes such as troponin, indicating damage to cardiac muscle. This kind of exercise can also result in small scars, that can interfere with the heart’s electrical conduction system. Overexercisers are more prone to rhythm disturbances involving the atria (the two smaller chambers of the heart), such as atrial fibrillation. Scarring can also cause rhythm disturbances in the ventricles (the two larger heart chambers), which can be more dangerous.

So if you want a long, good-quality life, by all means exercise. If you love intense exercise and you have a family history of heart disease or sudden death (usually caused by an arrhythmia), you should see a cardiologist before engaging in heavy exercise, even if you are school-age. The usual pre-participation sports physicals usually don’t pick up the congenital problems that cause young athletes to die on the field.

If you are 40 or older and intense and/or prolonged exercise has become an important part of your life, realize that as you age you may be taking some risk. At the very least, understand that the older you get, the more important rest/recovery days become.

If you are exercising and have chest pain; unusual fatigue or shortness of breath; notice heart speedups out of proportion to the exercise you’re doing; feel dizzy or faint; or notice palpitations or an irregular pulse, stop immediately and go to the nearest ER if you’re having chest pain or if you’re having other symptoms that are severe. If the symptoms don’t include chest pain and aren’t severe, don’t exercise again until you see your primary care provider, a cardiologist or an electrophysiologist, depending on the circumstances.

To learn more, read “Haywire Heart.”

Dr. Feinsinger, who retired from Glenwood Medical Associates after 42 years as a family physician, now has a nonprofit Center For Prevention and Treatment of Disease Through Nutrition. He is available for free consultations about heart attack prevention and any other medical concerns. Call 970-379-5718 for an appointment. For questions about his columns, email him at