Is It a Bad Idea to Exercise When I’m Sick?

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Written by Thomas Best, M.D., Ph.D., FACSM
Primary Care Physician, University of Miami Health System
Research Director, University of Miami Sports Medicine Institute

Thomas M Best

It can be frustrating to be sidelined by the common cold, but working out when you’re sick can worsen symptoms and slow your recovery. For those who work out or play sports regularly, not being able to exercise isn’t an easy prescription to fill. But, there are certain symptoms that can serve as a warning sign to stop or at least cut back on exercising until you feel better.

If you feel up to it, it’s safe to exercise when your symptoms are all above your neck.

These include a mild sore throat, runny nose, ear pain, or sinus congestion. Even so, it’s best to take it easy and reduce your workout’s intensity or duration, especially if you have less energy than usual.

Don’t exercise when symptoms are below your neck.

These include fever, vomiting, diarrhea, or a wet cough (with phlegm). These are signs that your body would benefit from rest.

When you have a fever over 100°F (or 37.8°C), your body is working overtime to fight infection. Adding exercise, particularly at high intensities, will further stress your system. In general, if your fever is above 101°F, you should not be exercising at all. This applies to both adults and children. With a fever like this, you probably won’t feel like getting much physical activity anyway.

While regular exercise has been shown to boost immunity, there’s no truth to the notion that an intense workout can aid recovery. In fact, it’s the opposite, as running a marathon can increase your risk of a cold or similar infection for at least two weeks following the race. During periods like this, you may want to try zinc tablets to boost your immune system.

Exercise increases your heart rate and body temperature, which can increase your risk for dehydration. If you’re already running a fever and get dehydrated, this can impair your ability to regulate your body temperature. Significant increases in body temperature are dangerous.

In addition, having a fever will most likely make you feel fatigued and decrease your muscle strength, endurance, speed, coordination, and tolerance for physical exertion. Avoid overexertion and injury by taking a break from physical activity.

Once your fever breaks (body temperature lowers, and you suddenly feel hot and sweaty instead of chilled), I recommend waiting a day or two before resuming exercise. During this time, stay well hydrated, eat a balanced diet, sleep at least as much as you normally do, and avoid overexertion.

While you’re recovering, listen to your body.

Rest when you need to, and ease your way back into your normal workout routine. It may take a few weeks for you to return to your usual intensity and duration, so be patient.

Keep in mind that some symptoms of COVID-19 infection are the same as those of the common cold, a sinus infection, an upper respiratory infection, or the seasonal flu. The above medical guidance is intended for generally healthy adults infected with the common cold or a mild viral or bacterial infection — not COVID-19. If you feel sick and may be infected with the novel coronavirus, use the symptom checker, socially distance, and wear a mask even at home around family and friends until symptoms resolve. If appropriate, get tested for COVID-19.

If you feel ill in any way, take measures to limit the spread of infection to others. Wash your hands and disinfect gym equipment and commonly touched surfaces.

While it’s natural to want to exercise with other people, this is the time to self-isolate and not give others your germs.

 


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