Should You Work Out When You're Sick? Here's When You Need To Be The Most Cautious, According To Research

Her palms are sweaty, knees weak, arms are heavy. There's vomit on her sweater already, mom's spaghetti. No, I'm not rapping along to Eminem's smash hit "Lose Yourself." I'm talking about you being sick AF right now. If you're a dedicated gym-goer, you might be considering sucking it up, putting on a brave face, and hitting the StairMaster so you can "sweat it out." Before you pull the trigger, though, let's discuss this. Should you work out when you're sick? There's a solid possibility the decision to go even when you feel like you've been hit by a semi isn't heroic at all. In fact, it could be plain old foolish.

While some of the answers are somewhat vague and subjective, there are a few general things science seems to agree on when it comes to working out when you're sick.

Tackling Your Sweat Sesh While You Have A Fever

Let's get one thing out of the way, first. While science is still split about whether a fever is a sure sign you're contagious — Prevention says it's a common myth — the general consensus is yes, it is, as HealthLine reminds us. And when your temperature is skyrocketing, you need to be extra cautious.

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Regardless of which side of the fence you fall on, if you have a fever, play it safe and stay home until it goes down. Wouldn't you rather be safe than sorry? (Of course.)

Furthermore, Dr. David Geier, an orthopedic surgeon and sports medicine specialist, gives even more reasons not to exercise with a fever. He notes it can make it especially challenging to regulate your body temperature, possibly increasing it further. It can even make your illness worse, causing your symptoms to be more pronounced and lengthening the time you are ill. This is one case where you simply will not sweat out the bad stuff. You'll only feel lousier.

TIME quotes David Nieman, a professor and director at Appalachian State University, echoing a similar thought: "A lot of athletes have this idea that, if I have a fever, I should sweat it out. That’s the craziest idea ever."

So, fever + exercise = no go.

Now, what if you don't have a fever but are otherwise sick?

Exercising With Mild Illness

Let's say you have a cold but feel well enough to still get a workout in. Smart move, or no? The Mayo Clinic says light to moderate exercise is typically safe and may even help you feel better, as it opens up your nasal passages and helps you breathe better.

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Sure enough, research published in the journal Medicine and Science in Sports and Exercise found moderate exercise had no effect on the severity or length of illness. Bear in mind that would include any positive effects, too. At least, though, it shouldn't make your cold worse.

The Mayo Clinic advises, however, you should hit the gym only if your symptoms are above the neck — like a runny nose or slight sore throat. If they are below the neck — like congestion in your chest, overwhelming muscle aches, or an upset belly — sit this one out. Nobody wants to have a coughing attack or have to run to the bathroom in the middle of working those back squats.

If you're stuck on what specifically you can do, think walking, light running, yoga, and swimming — activities that are low-intensity and low-impact.

Exercising With More Severe Illness

You don't have a fever, but it's not merely a cold, either. You do have the flu. Now what? Research widely agrees once your illness hits this point, rest and recovery are your best bet. One study from the 1990s published in the journal Sports Medicine, Training and Rehabilitation found evidence suggesting exercising with the flu could noticeably increase your odds of developing a type of chronic fatigue syndrome that could last for years.

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While total and complete rest — meaning sitting on your can and doing a whole lot of nothing — is frequently not in your best interest, in this case it might be, until you start feeling better. If the flu is plaguing you, pass on even the most low-intensity of workouts, and focus on sleeping and drinking plenty of fluids. Once you get to a place more akin to a harmless cold, it's probably safe to start thinking about getting your booty moving a little.

Perhaps as important as any research is this: listen to your body. Nobody knows you better than you. If you feel like it's best to skip the gym, it probably is. You're not weak or lazy — you're sick. Feel better!