You wake up in the morning with that little scratchy feeling in your throat, but you shake it off. As you get ready for work, make breakfast, and get the kids ready for school, you begin to sniffle. Yes, you are coming down with a cold. The question is should you cancel your exercise session today, or is it ok to exercise when you are sick?
Mild to Moderate Exercise for the Common Cold
Based on current knowledge, if the cold is confined to your head, such as a runny nose and sore throat without a fever or body aches, exercising is fine. Studies have shown that people engaging in mild to moderate exercise, such as walking, while sick with the common cold did not experience any more sever symptoms, longer cold duration or negative effects on exercise performance. In fact, some researchers suggest that mild to moderate exercise could speed the recovery of a minor cold by stimulating immune defenses. However, you don’t want to overdo it. Exercise seems to have a curvilinear effect on immune defense. Mild to moderate exercise supports immune defense responses, but as exercise become intense or prolonged, it suppresses immune defense. Exercise intensity can be resumed a few days after the cold symptoms have cleared up.
Rest for Systemic or Symptom Complex Illness
If your illness is systemic (whole-body) or symptom complex, such as respiratory infections, fever, swollen glands, extreme fatigue, and muscle aches and pains, rest is recommended. Exercise can be resumed after adequate rest and recovery. The actual length of recovery can depend on several factors, such as the severity of the illness, quality of rest, high levels of unmanaged stress, very low-calorie intake and rapid weight reduction. Ease back into your training program by taking 2 to 4 weeks to gradually resume intensive exercise.
Hampering the Spread of Cold Viruses
Contrary to my grandmothers warnings about going outside with wet hair, current research suggests cold viruses are passed from person to person primarily through nasal and airway passages. To hamper the spread of cold viruses, coughs, sneezes and “nose-blowing” should be smothered with a tissue, or as my father use to do, with a handkerchief. Wash your hands often with soap and water to avoid spreading cold viruses to your surroundings, and disinfecting your workout area would be greatly appreciated by your fellow fitness enthusiasts. To keep your immune system healthy and strong, current knowledge suggests eating a well-balanced diet, managing stress levels, preventing chronic fatigue, getting adequate sleep, and participating in daily exercise.
Summing Up
•   Do exercise at mild to moderate intensity if the cold symptoms are from the neck up.
•    Mild to moderate exercise includes (but not limited to) walking, light resistance training and stretching.
•    Intensive exercise maybe resumed a few days after the symptoms have cleared.
•   Don’t exercise with fever, extreme fatigue, swollen glands, muscle aches and pains.
•    Ease back into your exercise training and allow approximately 2 to 4 weeks before resuming intensive exercise.
•    Do eat a well-balanced diet, manage stress, prevent chronic fatigue, and exercise daily for a healthy immune system.

Reference:
Nieman, D.C., Weidner, T., and Dick, E. Exercise and the common cold.
http://www.acsm.org/AM/Template.cfm?Section=current_comments1&Template=/CM/ContentDisplay.cfm&ContentID=8635
American College of Sports Medicine. (2009). Protect against colds with exercise. http://www.acsm.org/AM/Template.cfm?Section=About_ACSM&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=13537