Sweat It Out or Stay in Bed? Experts Reveal When It’s Safe to Exercise While Sick

A quick "neck check" could be all you need to decide whether to sweat it out or stay in bed. Here's what sports medicine specialists recommend before you lace up your sneakers while sick.

There's nothing more motivating than finally gaining momentum in your fitness journey and seeing your hard work pay off. At that point, it's easy to feel unstoppable. That is, until something like the flu threatens to slow you down.

If you're wondering whether it's safe to work out while feeling under the weather, experts say it depends. According to the American Lung Association, mild or moderate exercise is generally fine if you only have mild cold symptoms, such as a runny nose, nasal congestion and sneezing.

More often than not, however, exercising while sick isn't a great idea. It could worsen your symptoms, raise your risk of injury, prolong your recovery and put others at risk of catching what you have.

If you're struggling to decide whether to still hit the gym, there are a few factors to weigh. When you're tempted to exercise but aren't feeling your best, start by giving yourself a "neck check."

"A simple rule to follow: If your symptoms are above the neck — likely a runny nose or congestion — it's probably safe to exercise," says Cleveland Clinic sports medicine physician Heather Rainey, MD.

However, if your symptoms affect several different parts of your body, Dr. Rainey recommends resting instead, especially if you have asthma or a heart condition.

Dr. Michael Jonesco, a sports and internal medicine specialist at The Ohio State University Wexner Medical Center, shares that view. He notes that if your illness brings on symptoms below the neck, you'll probably want to stay home.

Those include "things like bad gastrointestinal symptoms, significant myalgias [muscle pain] or body aches, even a fever, which is a sign of systemic illness — you know, that your whole body is mounting this inflammatory response to try to heal a systemic bug," Dr. Jonesco said. "These are all things we say, look, probably [take] 48 hours of rest and reassess."

"A fever indicates that something a little bit more serious is going on," warns Dr. Rainey. "Anytime you add the stress of exercise on top of it, we worry you may start to have issues with dehydration and managing your body temperature."

If you've already lost fluids through vomiting or diarrhea, pushing yourself too hard could even cause you to pass out. According to Dr. Jonesco, the neck check rule of thumb works because most problems above the neck don't involve the heart and lungs. "That's really what we're trying to protect," he said.

"Listen to your body," she advises. "If you're not feeling great, maybe don't do your most intense workout." And if you start to feel worse, stop and rest.

"Sometimes, it's best to just rest for a couple of days and do something more restorative so your body gets the resources it needs to get better," says Dr. Rainey. "Even if you take a couple of days off, you'll bounce back pretty quickly."

Once you're back on your feet, you can ease into your routine with simple exercises, including a few for stronger, more stable knees.