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Is it safe to exercise when I’m sick?

April 03, 2018 | UC Irvine Health
man exercising while sick

Exercise: It lowers the risk of heart attacks and strokes, as well as the chances of developing many chronic conditions requiring medications that in turn cost the U.S. health system bundles.

Physical activity also boosts immune systems and moods, increases life spans and improves quality of life.

It is so beneficial that Brian Y. Kim, MD, a UCI Health primary care physician who also specializes in sports medicine, considers exercise to be medicine.

Yet sometimes when you’re feeling under the weather, it’s best to skip a workout lest you make yourself sicker.

Whether to exercise or not depends on the type of illness you have and the physical activity you’re considering, Kim said. He offered the following guidelines.

Neck and up, work it out

As a rule of thumb, it’s generally safe to exercise if your symptoms are from the neck up, such as sore throat, stuffiness or earache.

Engaging in cardiovascular, muscle strengthening or other sports activities when you feel up to it shouldn’t compromise your ability to get well. It may even help get you back on your feet a bit sooner and improve your mood.

Shoulders on down, take a break

If your symptoms are below the neck — fatigue, muscle ache, productive cough, gastrointestinal distress — it’s best to take a few days off. Vigorous exercise might make you feel worse, plus it could add days to the healing process.

Instead, consider yoga, balancing exercises or stretches when your illness is at its peak.

Working out when you have a fever over 100 degrees can increase the risk of heat-related injury and dehydration, especially if you’re in a hot or humid environment. It’s best to avoid exertion.

Consider your medications

If you’re taking over-the-counter analgesics such as Tylenol or Dayquil for a mild ailment, it’s OK to exercise. Related: Use care with acetaminophen ›

But if you’re relying on those or other medications to feel normal, be aware that the drugs are likely masking more serious symptoms, which means you should take a break.

Decongestants, such as Sudafed or Afrin, are also concerning because they affect blood vessels in such a way as to make it harder for your body to regulate heat and cool off. So stay away from intense workouts, especially if you have a fever or are exercising in a hot environment.

Evaluate your symptoms

“The threshold for exercising depends to a certain extent on the individual,” Kim said. “You also have to take into account the severity of your sickness — the sicker you are, the more you should rest.”

But say you’ve been training for months for a race or competition and you feel a virus coming on, or you wake up on event day with a full-blown cold?

“A few days off your training shouldn’t make a difference in your fitness,” Kim advised. “It’s also important to be realistic about your goals. If you get sick on race day, you might have to expect a slower time. Or if your symptoms are severe enough, you may have to bite the bullet and sit out the race.”

“Just because a professional athlete like LeBron James is playing a basketball game with a fever and the flu doesn’t mean you should.”

Be considerate of others

If you are exercising when you have mild symptoms, don’t forget that you’re infectious from a day before you get sick until several days into the illness. Make sure to wipe down exercise equipment in gyms.

That’s a pretty good practice for healthy people, too, especially during cold and flu season.

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