While exercise is helpful to vitalize the immune system to fight off disease, it is not always advisable once you fall sick. At times, it's good to step back and take some rest. However, there are times when light intensity activity may help you feel better. The question is when to get up and move and when to take the day off?
Points to keep in mind:
If your symptoms are neck up—things like sinus and nasal congestion, sore throat, etc.—exercise neither helps nor hurts.
If your symptoms are below the neck, you should probably consider taking advantage of that rest day.
If you have the flu or other forms of fever-causing systemic infections, exercise is a bad idea.
If you feel up to it, keep your regular routine. Some people feel better when they get in a good sweat.
If you feel like you want to do something active but just can't fathom your normal workout, consider scaling back on the intensity.
If you find that the physical exertion makes you feel worse rather than better, stop and rest until you are well again.
Go for a walk instead of a run. Do some yoga instead of strength training.
If you go to the gym, be considerate of others. Wash your hands before you go. Apply hand sanitizer throughout your workout to lessen the spread of germs.
Exercise is not recommended if you have these symptoms:
Wheezing, coughing, chest tightness