You've got a miserable cold, but are anxious to get up and around again. Is it okay to hop on the treadmill, or will that use up energy that you need to fight off the bug?
Use good judgment, doctors say. It's usually all right to exercise as long as you feel okay, your symptoms are minor, and you don't overdo it. But going to the gym and pushing yourself too hard is not a good idea. Vigorous exercise can stress the immune system. Also keep in mind that you might spread your illness to others. Wash your hands with soap and water frequently or use hand sanitizer.
Symptoms above the neck: Some experts say that exercise in moderation is fine if your symptoms are mild and above the neck - such as a stuffy nose, sneezing, or scratchy throat. Just be sensible and reduce the length and intensity of your workout. Think "low-impact." For example, if you usually jog 30 minutes, consider a 15-minute walk instead. But remember, feeling sick may be a sign that your body needs a rest.
Symptoms below the neck: Exercise is not usually advised if you have symptoms below the neck, such as muscle aches, vomiting, diarrhea, chills, or a cough. And don't exercise if you have fever or feel extremely tired. In all these cases, working out could put stress on the immune system that could hamper recovery or make you feel worse.
Easy does it
When your illness seems to be letting up, slowly work back into your fitness routine. Give yourself several days of rest after a bad cold and at least a week or so after the flu before you go full-tilt. Depending on how sick you were and what your doctor advises, you may need to wait up to 2 weeks before hitting the gym again.
When resuming workouts, limit the intensity and duration of your sessions for a few days or weeks after your illness. Perhaps plan on exercising half your usual time. Or go half-speed on aerobics and lift less weight until you regain your endurance and strength. When you find that you are no longer exhausted, you'll know it's time to ease back into your regular routine.
Don't worry about losing the fitness gains you made before you were sick. Taking a little time off doesn't mean you have to go back to square one. On the other hand, working out too soon or too hard before you are fully recovered can put you back in the sick bay.