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Exercising—or Not—When You Are Sick

William A. Primos, Jr, MD with James R. Wappes


You're not feeling great. You have a sore throat, stuffy head, and runny nose. But you feel like you could maybe log a few road miles. Should you?

Whether you're a low-key exerciser or a competitive athlete, knowing when to work out if you don't feel well can be difficult. When you have an infection such as a cold, "stomach flu," or contagious skin condition, you (and, often, your doctor) need to decide how exercise might affect your health, your performance, and the health of others. Of course, it's also good to avoid infection in the first place.

Should You Play On?

The first question to ask your infected body is if you need to push it. When your body is fighting an infection, your performance and fitness benefits will likely be less than optimal, so why bother? Missing a few days of training is not the end of the world-and it may even be a better option. And if you're a competitive athlete, taking yourself out may be the best thing for the team.

Sometimes, though, physical activity helps you feel better. For example, working out can sometimes temporarily clear a stuffed-up head when you have a cold.

So if you think exercise might help, or if you can't bear to miss a workout, do a "neck check" of your symptoms (1). If your symptoms are located "above the neck"—a stuffy or runny nose, sneezing, or a sore throat, for example-then exercise is probably safe. But start at half speed. If you feel better after 10 minutes, you can increase your speed and finish the workout or game. If you feel miserable, though, stop.

On the other hand, your "neck check" may reveal "below-the-neck" symptoms. Avoid intense physical activity if you have any of these symptoms: muscle aches, hacking cough, fever of 100°F or higher, chills, diarrhea, or vomiting. Exercising when you have below-the-neck symptoms may mean, at best, that you'll feel weak and dehydrated. Worse, you may risk such dangerous conditions as heatstroke (dangerously high body temperature) and heart failure.

You can resume exercising when "below-the-neck" symptoms subside. However, when recovering from an illness that prevented you from working out, it's important to ease back into activity gradually. A good rule of thumb is to exercise for 2 days at a lower-than-normal intensity for each day you were sick.

Stop the Spread

If you're on a team, an additional concern is whether you will infect others. And if you're healthy, you may wonder about someone else infecting you. For common illnesses like the cold, practice commonsense hygiene like washing your hands frequently and directing coughs and sneezes away from others.

Some infections, though, are readily spread in sports and require athletes to be sidelined while they are contagious. Two such conditions are measles and herpes simplex (a virus that often causes cold sores or blisters and is transmitted via skin-to-skin contact, as in wrestling). If you may have such an infection, see a doctor for treatment and information about when to resume sports.

Other conditions can also spread readily. So in addition to regular hygiene, athletes need to refrain from sharing water bottles and towels. Infections have been known to pass to other athletes via both routes.

You should also be properly immunized against diseases such as measles, mumps, tetanus, and rubella. Also, some athletes may benefit from an influenza vaccine. Ask your doctor what immunizations you need.

Common Cold, Common Sense

As is often true, deciding to exercise when you are sick largely involves common sense. Taking precautions about spreading infection and listening to your body can go a long way in getting you back into action without serious problems.


  1. Eichner ER: Infection, immunity, and exercise. Phys Sportsmed 1993;21(1):125-135

Remember: This information is not intended as a substitute for medical advice. If you have concerns about your health, consult a physician.

Dr Primos practices primary care sports medicine in Charlotte, North Carolina, and is a charter member of the American Medical Society for Sports Medicine.