Exercise can be hazardous to your health. Even deadly. Consider this scenario: Your leg is broken and in a cast. To help promote healing, will your doctor advise you to rest and keep your leg propped up, or to dance, do jumping jacks, and hop on that broken leg? The obvious thing to do is rest.
But what if you have a bad cold? Should you skip that kickboxing class you have this afternoon? Definitely. Engaging in vigorous exercise while you are sick is dangerous. The idea that you can sweat out your illness through intense exercise is a myth. The only thing you’ll be sweating out is your white blood cells. That’s because research has found that your immune system does not function as effectively during – and up to 72 hours after – heavy exercise.
How your immune system responds to exercise is indeed an interesting topic that merits your attention. Did you know that research has found that athletes who engage in heavy training are at greater risk of contracting upper respiratory infections than healthy, sedentary people? Ironically, when I dropped those seven sizes and was in the best shape of my life, I contracted an upper respiratory infection that eventually turned into pneumonia and landed me in the hospital.
How could this happen? Well, it turns out that when you engage in continuous, intense exercise, your body undergoes changes that impair your immune system. Some of the processes that result are fairly complicated and require a whole scientific explanation which I will not cover here, but you can get a brief overview of them on p. 239 here. Therefore, the risk for infection can increase, and if you are already sick, exercise will make it worse.
The research seems to point to vigorous exercise as the culprit for a suppressed immune system, citing that moderate exercise does not produce the same effect, and can perhaps strengthen the immune system. This is a decision that should be a well-thought-out one for you. Discuss things with your doctor, but become your biggest advocate by getting informed and listening to your body.
Sickness is not the only thing that can keep you from exercising. If you are on a recommendation from your doctor to decrease physical activity (say, for a high-risk pregnancy), then you should follow the advice of your physician. If you are dealing with a health issue, it is important to discuss with your doctor how you should incorporate exercise into your life.
The pneumonia I dealt with several years ago caused a huge blow to my immune system, and it has never fully recovered. I get sick a lot easier now, and it takes me longer to recuperate when I do.
There are some generally accepted recommendations regarding whether you should exercise when sick. These come from an article by Dr. David Nieman, a professor of health and exercise science:
- If you have a common cold (without the fever and body aches), intense exercise can be resumed a few days after the symptoms completely go away.
- Mild to moderate exercise (like walking) does not appear to be harmful if you have a common cold.
- If you suffer from the following symptoms: fever, extreme tiredness, muscle aches, and swollen lymph glands, you should wait 2-4 weeks before engaging in vigorous exercise.
Sometimes, depending on your illness, you may need to wait longer. I have had to. And you know what? Contributing to your dream body in a big way is still possible, even when you have to go weeks or months without exercise. Your diet can make significant contributions to your ultimate weight-loss goals.
Rather than being hard on yourself because you cannot exercise, focus your efforts instead on recovering. Do what you can to get better. And when you do start exercising again, start slow. Give your body a fair chance to adjust. Your health will thank you for it.
