How long should I wait after the flu before resuming exercise?

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Q. I have just recovered from the flu. How soon can I resume exercise again and can I go straight back to my previous routine?

A. The recommendations about when to return to exercise after respiratory infections, such as the flu, colds, or bronchitis, are vague. One major reason is that each person's response to illness is so variable. But here is my general advice.

Most healthy people who have a cold or mild bronchitis without a fever or significant cough can continue to exercise during their illness. However, you initially want to cut your intensity and duration in half. If you feel good later in the day after your lighter workout, you can gradually increase how much you do during your next session. But if you feel exhausted after exercising, take off an extra day before working out again.

With the flu or any respiratory illness that causes high fever, muscle aches, and fatigue, wait until the fever is gone before getting back to exercise. Your first workout back should be light so you don't get out of breath, and you want to progress slowly as you return to your normal routine. You may be tempted to ramp it up, but it's best to go low (low intensity) and go slow (short duration).

— by Howard LeWine, M.D.
Editor in Chief, Harvard Men's Health Watch