Exercising while sick: What are the rules?

As the months get cooler, it’s tempting to avoid working out to sleep a little longer in the morning or stay rugged up on the couch at night.

It’s also the time of year when winter colds, drippy noses and sore throats can make exercising feel like a bad idea.

But can exercise actually help heal us faster or are we doing more damage by hitting the gym when we’re sick?

We asked Toby Mündel, a professor at Brock University's Department of Kinesiology, to find out whether or not the sniffles mean you need to skip your workout session or if exercise is really the best medicine.

The human body is constantly under attack from disease-causing germs (pathogens) like bacteria, viruses and fungi that want to enter and use the body’s resources for themselves.¹ Thankfully, most people’s immune systems do a great job of defending against any invading pathogens. But your immune system can’t fend off everything, resulting in most adults succumbing to at least 2 to 4 colds a year.²

There are lots of ways to support your immunity, but when it comes to exercise, it might just be the boost you need to help ward off winter nasties.

Studies suggest regular moderate exercising (less than 60 minutes a day of walking, running or cycling) can enhance immune defence activity, more than halve your risk for respiratory infections and help fight off the common cold.³

But what do you do if a cold has totally wiped you out? Is exercise still the cure?

Common sense and listening to your body can go a long way, especially when you’re sick. If you’re not feeling up to the 5km run you had pencilled in, then give it a miss.

However, if you’re feeling okay there’s no reason to put yourself to bed, says Mündel.

“If your symptoms are above the neck, such as runny nose, nasal congestion and a sore throat, you’ll still be able to manage a workout, though at a lighter-than-normal level. And in some cases, working out while sick could leave you feeling better.”

Research reveals that exercising with a cold does not increase the likelihood of getting sick again and in some cases can reduce the severity of symptoms.⁴

So, if you only have mild symptoms above the neck and want to workout, go for it. Just make sure you’re not pushing yourself too hard to where it’s difficult to catch your breath and stay well hydrated.

The more we exercise the better, right? Not necessarily, says Mündel.

For those who regularly do either very intense and/or long-duration exercise, such as athletes and avid trainers, Mündel says they’re 2 to 6 times more likely to get sore throats and flu-like symptoms than the rest of the population due to the release of stress hormones.⁵

The good news? Sex, age and activity aside, Mündel says that at least 20 minutes of activity (enough to get you huffing and puffing) most days of the week, if not all, should be enough to benefit your immune system.

“You can get these benefits if you are working out when sick, but you may want to avoid taking it too far,” says Mündel.

If you’re sick and wanting to exercise, you still need to proceed with caution and pay attention to how you feel before lacing up your running shoes.

“If you are feeling exceptionally fatigued or dizzy, you should consider resting as much as possible, especially if you’re already having trouble finding the energy to complete other daily tasks,” says Mündel.

If your symptoms are below the neck, such as chest congestion, cough, nausea or diarrhoea, or if you have a fever, muscle aches or widespread fatigue, “then you should swap your training for some R&R, regardless of how you feel,” says Mündel.

This can be a serious thing for people who push too hard, too soon while sick or shortly after, leading to lingering symptoms, exhaustion and unexplained pain.

Similarly, if symptoms worsen with exercise, or begin to evolve into something more sinister like the flu or bronchitis, Mündel recommends stopping and resting until you’re recovered. It's also a good idea to see a doctor if symptoms get worse or don’t improve.

It’s worth noting that we all have a responsibility of not spreading germs when we’re sick. If your illness is contagious, it's sensible to avoid exercising in public spaces or gyms to prevent infecting other people. If you really want to exercise, opt for at-home workouts or outdoor activities where you can maintain distance from others.

Remember, if you’ve been sidelined by an illness, respect your body's limitations and give it the time and space it needs to heal. You can always restart your routine gradually when you’re feeling better.