Learn whether it’s safe to work out when you’re not feeling well, and what types of workouts are best.
A hacking cough, sinus congestion, and muscle aches—those first symptoms of illness can trigger alarm bells in your head and send you running to the drugstore in search of a quick remedy. Not only can a common cold or the flu leave you stuck in bed for days, but it can also drain your workout momentum, especially if you’ve been going strong in a workout program. Do you push through or give yourself the day off? Will exercising while sick make you feel better or worse?
Here, Dr. Robby Sikka, M.D., team physician for the New York Yankees, senior principal consultant for the Denver Broncos, and senior medical consultant at Tonal, explains how to know when to keep going with your workout, when to call it quits, and how exercise affects your immune system.
Should You Exercise While Sick?
Most experts use the “neck rule:” When deciding if you exercise while sick, you’re safe to exercise with above-the-neck symptoms such as a stuffy nose, but it’s best to take a day off with below-the-neck symptoms such as a chest cold, cough, or nausea.
Sikka, however, takes a more nuanced approach. For below-the-neck symptoms that are less severe, he says gentle exercise may actually be beneficial.
“There are positive effects of exercise in terms of clearing your lungs and improving your blood flow so that you can increase your production of white blood cells,” he says. “A small rise in temperature can actually help reduce bacteria and improve your immunity.”
Sikka draws the line at systemic symptoms such as fever, chest pains, gastrointestinal symptoms, or significant muscle pains and body aches. In these cases, exercise is more likely to lead to worsening symptoms or injury.
Instead of the neck rule, Sikka recommends asking yourself these two questions before exercising while sick: Do you feel good enough to work? Does exercise worsen your symptoms?
“If you don’t feel good enough to do your job, you’re probably not in a good enough situation to exercise,” he says. And if you feel like even moderate exercise will aggravate your symptoms, you’re better off taking a rest day. “Do a warmup, and if the warmup is okay, proceed, and be aware of whether your symptoms are worsening or it’s just fatigue,” says Sikka.
Finally, Sikka says it’s essential to prioritize sleep, hydration, and nutrition when you’re sick. If your illness is preventing you from optimizing these factors that are essential for recovery, exercise won’t do you any good.
“If you aren’t getting enough sleep or if you’re not hydrating, you probably shouldn’t exercise because you’re not going to get the benefits,” he says. “That’s where you should spend your time and energy: Trying to get the appropriate nutrition and trying to get a little bit of rest.”
How Does Exercise Affect Your Immune System?
Although you don’t want to push your body too hard exercising while sick, regular workouts the rest of the time will actually help keep you healthy. According to a large review of studies, moderate exercise on a near-daily basis reduces the incidence and severity of upper respiratory tract infections including influenza and pneumonia.
“Physical activity reduces your risk of getting a cold,” says Sikka. “Exercise, through increasing your blood flow and increasing your body temperature actually helps to produce better immunity and slows down the release of stress hormones.”
Even in the case of viruses like Covid-19, a review of studies has shown that regular exercise reduces the severity of symptoms and mortality rate.
However, you might experience a temporary drop in immunity if you’re pushing beyond your limits or overtraining without proper recovery. For example, it’s been shown that marathon runners exhibit immune system dysfunction that creates an “open window” for infection for up to 72 hours after the race.
What Exercise Can You Do While Sick?
As a general guideline, Sikka recommends starting with a workout that’s 50 percent of your usual volume and 50 percent of your typical intensity. Exercise creates stress on the body which, when you’re healthy, triggers adaptation like muscle growth and fat loss. But when you’re sick, increased stress hormones can weaken your immunity and your body’s ability to fight off illness.
Additionally, Sikka recommends not letting your heart rate go above 75 percent of your maximum. Citing the risk of rare, but serious, post-viral heart conditions such as myocarditis, he says it’s best to avoid making your heart work harder than it has to during an illness.
The amount of exercise you can tolerate while sick also depends on your normal activity level. “If you’re doing something consistently, your body’s probably not going to take it as a stress. It’s just going to feel normal,” says Sikka. For people who exercise regularly, doing a similar workout at a reduced duration and intensity shouldn’t create too much physical stress.
On Tonal, recovery workouts at reduced weights make it easy to still get your workout in while reducing intensity. As a form of active recovery, these sessions will boost blood flow and speed up healing without pushing you too hard. Mobility, meditation, and gentle yoga classes are also safe options for moving your body while you’re recovering.
No matter what exercise you do during your illness, Sikka emphasizes the importance of rest, whether that’s between sets or between workout days, to allow your body time to recover. Now is not the time to start working out four days per week if you typically only do three, and you’d likely be better off taking a step back for now.
Bottom line: Listen to your body if you’re not feeling well and ease back into exercise gradually. Once you’re feeling better keep up your workout routine for stronger immunity.
The information provided in this article is for educational and informational purposes only. Individuals with pre-existing health conditions, injuries, or concerns should consult with their healthcare provider before trying a new exercise or nutrition regimen.