Can It Prevent the Flu or a Cold?
Maybe. The best way to stay well is to keep your immune system strong. When you exercise, your white blood cells -- the ones that fight infections -- travel through your body faster and do their jobs better.
Regular exercise may be the ticket. And you don't have to run a marathon, either. Moderate activity is all you need.
Some studies show that "moderate intensity" exercise may cut down the number of colds you get. That type of activity includes things like a 20- to 30-minute walk every day, going to the gym every other day, or biking with your kids a few times a week.
In one study in the American Journal of Medicine, women who walked for a half-hour every day for 1 year had half the number of colds as those who didn't exercise. Researchers found that regular walking may lead to a higher number of white blood cells, which fight infections.
In another study, researchers found that in 65-year-olds who did regular exercise, the number of T-cells -- a specific type of white blood cell -- was as high as those of people in their 30s.
There are other benefits to being more active, like less stress and better sleep. Stress is bad for your body and mind. You can ease it with regular exercise. Get 7 to 8 hours sleep a night, too, because that also helps keep your body's defenses in good shape.
On the other hand, too much exercise -- like spending hours at the gym or running marathons -- can bring your immune system down. Extreme workouts can slash the number of white blood cells you have and boost the level of stress hormones in your bloodstream.
Can I Work Out if I Have the Flu?
Try to take it easy. Rest gives your body a chance to recover. Your immune system works best when it isn’t in overdrive.
If you have a fever, skip the workout. People usually run a fever for 2 to 5 days when they have the flu. It means your body is battling the infection. A high temperature pulls moisture out of your body. So does a workout. If you get too dried out, it could delay your recovery.
Also, the flu is contagious. You can spread it to others for up to 7 days after your symptoms start. If you work out around other people, wait until your fever breaks and stays down on its own for at least 24 hours before you go back to your routine.
If you don't have a fever yet but you do have other flu symptoms, talk to your doctor before you head to the gym.
What About When I Have a Cold?
It's usually safe to do it as long as you listen to your body. You'll need to watch out for certain risky situations.
Physical activity increases your heart rate, but so can some cold medicines. So a combo of exercise and decongestants can cause your heart to pump very hard. You may become short of breath and have trouble breathing.
Also be careful about working out too hard when you have a cold. It can make you feel worse and slow down your recovery.
Too Much Exercise May Increase Colds
It's not a problem for most of us, but if you're an exercise fiend, make sure you take time for rest and recovery after periods of intense training.
When workouts get too strenuous, the number of infection-fighting white blood cells in your body can go down. At the same time, your stress hormone cortisol may go up, which may interfere with the ability of certain immune cells to work right.
When Should You Call the Doctor About Exercise and Colds?
If you exercise with a cold, call your doctor if you notice:
- Your chest is more congested.
- You cough and wheeze.
Stop your activity and get emergency medical help if you:
- Feel chest tightness or pressure
- Have trouble breathing or get very short of breath
- Get lightheaded or dizzy
- Have problems with balance