Man is this a good question or what? I get asked this so often and understandable so. It is hard to know if you are helping or hurting the miserable state you currently are in. Steve Edwards from Team Beachbody has some thoughts on this great question.
When you’re sick, your body uses its recovery properties to fight the illness. When you exercise, you use these same properties to recover. To your body, trying to exercise when you’re sick is effectively the same thing as overtraining. You won’t be able to recover from exercise, rendering it useless, as well as increasing the risk of making your illness worse and lengthening your downtime.
Believe it or not, there are actually a couple of upsides to being sick. It both raises your metabolism and heightens your immune response, meaning that you can eat more than normal and not gain weight. Your immune system also releases performance-enhancing hormones that both fight the infection and help you heal microtrauma incurred during your training program. Because of these factors, when I’m sick during a training cycle I consider it my recovery week. Here is my protocol:
At the onset of symptoms I bump my vitamin C and zinc levels, drink a ton of water, and sleep as much as possible. If I catch it early enough, I’ll miss the cold. However, your body plays an insidious trick on you at the onset of a cold. Before you feel symptoms, your adrenal system kick-starts the immune response, which often results in a great workout—too good. Prior to a competition, if an athlete sets a personal record or looks too strong, their coach will often shut them down in anticipation of potential pending illness. If a workout feels spectacular out of the blue, consider backing off and adding immune-boosting supplements to your regimen.
Once I know I’m sick, I rest as much as I possibly can. I clear my social schedule, work as little as possible, and shelve any projects (even mental ones) that can wait. My diet becomes very clean. No coffee, alcohol, sugar, junk, and I drink a ton of water. Also, I eat a lot of small meals all day long. Your body needs nutrients when it’s sick but doesn’t want the energy burden of digesting large meals.
Finally, there are times when you’re sick when hard exercise might help, but it’s rare. The most common is near the end of a cold, where the infection has run its course but you still have minor symptoms. You might have heard someone say, “I blew the cold out of my system” with exercise. Just be careful you don’t try this too early or you’ll get worse. Patience may not be your favorite part of training, but sometimes you gotta not do what you gotta not do.