How to build muscle back after being ill for a long time when you get to the gym is to start slow. You know you're not a beginner, but your muscles don't remember that fact. You will need to start Nitro X Pro Muscle Building just like when you were a beginner and let them build over time. Don't make the mistake that many people do and let their ego get the better of them. If you work your muscles too hard after being ill for a long time, you are likely to tear them, or worse. It's not worth an injury that will put you out of commission for even a longer period of time, is it?