Should You Work Out When You're Sick?

As a general rule, no. If you have a virus or bacterial infection and are at the very tail end of it with at least 90% energy, strength training at less than full intensity might be OK. Use your judgment and listen to your body. But aerobics and oxygen-intense cross training should wait. You won't suffer by waiting another day or two. And your body shouldn't have to decide whether to focus on recuperating fully from an illness or rebuilding itself after a tough workout. If it has to, it will do both poorly.

Better off playing it safe and making sure you're 100% before heading back to the gym (or the court, road, the trail...)