Harvard Heart Letter

Ask the doctor: Does exercise help damaged heart muscle?

Ask the doctor

Does exercise help damaged heart muscle?

Q. After my heart attack, my doctor told me that damaged heart muscle cannot be replaced. If this is true, why am I walking on a treadmill five days a week? Is this helping repair the damage or strengthen what's left?

A. Your skeletal muscles can repair themselves after an injury — pull your calf muscle and, after a few days or so, it heals. Until recently, it was believed that the human heart didn't have this capacity. But some exciting research indicates that the heart does, indeed, have some ability to make new muscle and possibly repair itself. The rate of regeneration is so slow, though, that it can't fix the kind of damage caused by a heart attack. That's why the rapid healing that follows a heart attack creates scar tissue in place of working muscle tissue.

Walking (and other forms of aerobic exercise) after a heart attack does several things. It strengthens the remaining heart muscle. It keeps your arteries flexible, which makes it easier for your heart to pump blood through the thousands of miles of the circulatory system. It also helps fight atherosclerosis, the process that most likely led to your heart attack. This is crucial, because it is not the heart attack you just had that you should worry about — it is preventing the next one. Exercising five times a week is a great way to do this.

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