Clients ask us all the time, "Should I stay at home and rest or exercise when I'm sick?" and our answer is... "it depends". Of course if you are extremely sick, you should stay at home. There are some grey areas to clarify however.
David C. Nieman, PhD, director of the Human Performance Lab at North Carolina Research Campus says, "Based on…lots of case study data on athletes, we're telling people, if the symptoms are from the neck up, such as the common cold or runny nose, something easy, like a brisk walk, won't hurt or help". However, if your symptoms are a fever, wide-spread muscle weakness and tiredness, it's time to rest. "A systemic, viral illness like that can be harmful to your heart. Also, exercise might prolong these symptoms," he says.
The best thing to do is prevention. Our motto at Medical Exercise Trainers "Exercise is the key to most long term medical conditions and to the prevention thereof" is backed by thousands of studies. One of those studies published by the British Journal of Sports Medicine found people who exercise regularly take 43% less sick days than those who do not.
In the end, it's best to rest when systematically sick and get out and walk when it's just a "common cold" and runny nose. However, being active can greatly reduce your chances of getting sick in the first place.