Is Working Out While Sick Safe?

Learn when you're typically safe to exercise while sick and when you should skip your workout for the day. Plus, find tips on how to stay safe as you train.

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When a dead-of-winter cold — with its totally pleasant symptoms such as a runny nose and non-stop sneezing — hits you like a ton of bricks, you might debate whether continuing with your daily exercise routine is a good idea. While a bit of movement after lounging on the couch all day sounds rejuvenating, is working out while sick actually what the doctor would order?

Here, an exercise physiologist answers that very question. Plus, she breaks down how to stay safe and recover properly if you do decide to exercise while sick.

Should You Work Out When You're Sick?

If you’re itching to get in a workout while ill, there’s good news: For the average person, it’s typically safe to exercise while sick if you’re experiencing symptoms that occur above the neck, such as runny nose, headache, nasal congestion, or sneezing, says Heather A. Milton, M.S., R.C.E.P., C.S.C.S., a board-certified clinical exercise physiologist at NYU Langone Health's Sports Performance Center.

In fact, working out while sick may actually help you feel better, says Milton. As you exercise, your body releases the hormones and neurotransmitters epinephrine and norepinephrine, both of which increase your heart rate and contractility (the force of your heart’s contractions) and elevate your respiratory rate, she explains. Your muscles will receive more blood flow and oxygen, and your airways will open up to take in more oxygen, according to the Cleveland Clinic. And this fluid movement can simply make you feel more sprightly, says Milton. Your workout will also give you a hit of dopamine, a neurotransmitter and hormone that can boost your mood, which can be exactly what you need after sneezing in bed all day, she says. (It should go without saying, but you shouldn't exercise with others while you're sick with a contagious illness, so stick with solo workouts if that's the case.)

That said, you’ll want to skip your workout if you’re experiencing chest congestion or a hacking cough, according to the Mayo Clinic. The same rule of thumb applies if you’re dealing with a fever, says Milton. ICYDK, when you’re dealing with an infection, your body may temporarily elevate your temperature in an attempt to kill the harmful virus or bacteria, according to the National Library of Medicine. “If you have a fever, you are temporarily immunocompromised,” adds Milton. “And there’s a very, very short window of time after exercise where your immunity is decreased.” This dual layer of immunocompromise can make you more susceptible to other illnesses, so you're best off staying home, she explains. (FTR, exercise does improve your immune system over time, so this temporarily compromised state shouldn’t be a reason to skip your workouts entirely, she adds.)


How to Safely Exercise While Sick — and Recover Properly

Even if your symptoms are occurring above the neck and you feel well enough to exercise while sick, you shouldn’t tackle an incredibly demanding workout. Instead, stick with low- to moderate-intensity exercise (think: a light jog, a basic strength training session, a yoga practice) that’s simple to complete, as you may be feeling a bit more fatigued than usual. Plus, the higher the intensity of your workout, the more likely you’ll experience a temporary dip in immunity — and thus have a greater chance of catching another illness — afterward, says Milton. 

You’ll also want to avoid deviating from your usual routine, suggests Milton. “You can do a slow, steady, hour-long workout if you're used to doing that, but this is definitely not a time to try to do anything outside of your normal,” she adds. Translation: Hold off on your first powerlifting training session or an intense round of treadmill sprints until you’re illness-free.

As you ease your way through your workout, keep tabs on how you feel; if you develop lightheadedness, increased shortness of breath, nausea, or a racing heart, that’s your cue to stop exercising, says Milton. During and after your training session, remember to stay on top of your H2O consumption. “It’s always recommended to increase fluid intake when you’re sick,” says Milton. “When your immune system is fighting an infection and you’re using metabolism [physical and chemical processes in the body that convert or use energy] to do that, you do utilize water,” she explains.

This fluid use, combined with the water you lose through sweat while exercising, means staying hydrated is particularly important. The exact amount of fluid you need varies from person to person, depending on the infection, your body weight, and other factors, says Milton. Your best bet: Aim to consume at least 11.5 cups of fluid per day, the baseline recommendation for an average, healthy adult living in a temperate climate, then bump up your intake to account for your sweat and immune system processes. Generally, you'll want to take in an extra 16 ounces of fluid for every pound of sweat you lose, as Shape previously reported.

Whether you’re suffering from a snotty cold or you’re simply feeling under the weather, prioritizing sleep is a must, says Milton. Getting just four hours of sleep for one night significantly reduces the activity of natural killer cells, a type of immune cell that can kill cells infected with a virus and tumor cells, which can increase the risk for viral infections, according to the Centers for Disease Control and Prevention. And sleep deprivation can also negatively impact fitness performance factors such as reaction time, submaximal strength, and endurance, research shows. “Sleep is always overlooked, but it’s integral to recovery if you’re sick or if you’re healthy,” adds Milton.

While working out while sick may be safe for you physically, you shouldn’t force yourself to train if you aren’t feeling it mentally. Your dumbbells and running sneakers can wait until you’re back to your completely healthy self.