Sweating Out a Cold: Working Out When Sick

You may have heard friends say they’re going to the gym in hopes of sweating out a cold—but, does it really work? Terry Kang, MD, UnityPoint Health explains all the things you should keep in mind if you’re considering working up a sweat while fighting off a bug.

The Science Behind Sweating Out a Cold

When trying to decide if you should consider sweating out a cold, it’s helpful to understand the effect exercise has on the body. Dr. Kang says working out usually boosts the body’s metabolism, as well as the body’s immune response. However, an intense workout usually has the opposite effect.

“During exercise, our body releases chemicals to repair itself and control the level of stress in our body. This is helpful in fighting of infections. When the levels of exercise get too intense, steroid is released by our body to fight off stress. Steroids decrease the ability of the cells that fight off infections to work and lowered our immunity, temporarily.”

The Good & the Bad of Exercising When Sick

If you’re wondering how much is too much working out with a cold, Dr. Kang says any mild to moderate, low-impact exercise for shorter periods of time, like 30 minutes, is OK and allows the body to boost immunity and metabolism to fight off infections, like a cold. Here are good ways to exercise while sick:

  • Walking
  • Light jogging
  • Yoga
  • Meditation

“When I’m sick, I generally stick to walking for 30 minutes. I advise my patients to participate in yoga and meditation because they have been proven to increase immunity,” Dr. Kang says.

If you are exercising when sick, make sure to focus on hydration. Drink plenty of fluids, and keep electrolytes in check with Pedialyte or other drinks containing electrolytes. Dr. Kang suggests skipping sports drinks, because while they may contain electrolytes, they also have a great deal of sugar, which can lead to diarrhea. 

On the flip side, if you’ve got a cold, exercising for long amounts of time, like two hours, isn’t a good idea and neither are any high-intensity options. Exercises you should skip while sick include:

  • Long races (like marathons)
  • Heavy lifting
  • Intense, interval-style workouts

Dr. Kang also says if your body is working to fight an infection, you may be weaker than normal and more vulnerable to injury.

Cold Symptoms You Shouldn’t Ignore

Dr. Kang says there are illness signs you shouldn’t ignore, especially if you are considering moderate to heavy exercise. If you notice any of the following symptoms, it’s just best to stay home and rest.

  • Fever
  • Muscle & joint pain
  • Vomiting
  • Headache
  • Diarrhea

“These symptoms are generally signs the infection is wide spread. It’s also a sign your body is busy fighting off infection and needs resources directed toward fighting off infection,” Dr. Kang says.

He adds, if you combine nausea, vomiting, diarrhea and/or sweating, you have an equation for dehydration, which isn’t safe. 

Germs at the Gym

If you don’t have a bug, the gym is a good place to get one. Dr. Kang says to keep in mind that a cold or flu can easily spread from person to person in an indoor gym, and you should take precautions to protect yourself.

“When you are in the gym, it’s easy to catch infection from other people. You are in close quarters where they are doing activities that may induce more coughing and bodily fluid loss. Make sure you wipe down the equipment before and after use. If you are coughing, you should be using a mask. Wash your hands before and after working out,” Dr. Kang says.

If you’re thinking about doing a short workout outside, Dr. Kang says you really should check the forecast first.

“You should avoid really hot or really cold environments that can quickly change your core body temperature. Your body uses temperature regulation as a way to fight off infections, such as a virus,” Dr. Kang says.

For example, running in the rain can cool down your body and prevent the body from raising its core temperature to fight off infection.

Post-Illness Return to Activity

Once the symptoms become mild, Dr. Kang says it’s OK to return to light to moderate exercise with caution.

“There is no hard guidance on how to return to exercise after resting from illness. You should keep in mind that you have used up your reserves inside to fight off the infection. Start low and go slow. Hitting the gym hard suddenly to make up for lost time can lead to muscle damage and other injuries,” Dr. Kang says.

What the Doctor Recommends

Overall, Dr. Kang says to listen to your body when determining if you feel up for getting in some exercise when sick. If you do choose to be active:

  • Keep it mild
  • Aim for shorter amounts of time
  • Take frequent breaks
  • Hydrate properly

“One study on mice tells us a good story on exercise. Three sets of mice were given flu virus. The first set included sedentary mice and least number of mice from this group caught the flu. The second set did 120 minutes of running on treadmill. Unfortunately, they had the highest number of flu infection and death from it. The third and last set of mice performed light running on a treadmill. This group had a higher number of flu infection than the sedentary group, but they recovered faster and the number of deaths was much less. From this experiment, we drew the conclusion that light exercise can expose you to more flu, but you can recover faster and have fewer complications,” Dr. Kang says.