Whether you are starting to work out for the first time or you are a professional athlete, muscle fatigue is a normal side effect of exercise that may put a damper on your routine. Fatigue is your body's way of adapting to a fitness regimen and making you aware that you have reached your metabolic/psychological limit. It's common to get tired after a long or tough workout. In general, this occurs because your muscles run out of energy. Your central nervous system also loses its ability to keep moving your muscles. This causes muscle fatigue, making you feel tired
