Harvard Men's Health Watch

On call: Exercise and free radicals

On call

Exercise and free radicals

Q. I love to work out, but I just read that exercise would produce free radicals in my body. Am I doing more harm than good by going to the gym?

A. Free radicals take the rap for everything from cancer and heart disease to Alzheimer's disease, cataracts, and aging, but the situation is actually much more complex.

Free radicals are molecules that are missing one member of a pair of electrons. Since that leaves an electron without a partner, the molecule is internally charged up "" it has extra energy and is unstable. Nature abhors instability, and free radicals try to dump their extra energy by reacting with normal molecules. Sometimes that reaction generates more free radicals, but sometimes it can damage DNA or cell membranes, perhaps contributing to various diseases.

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