Originally Posted by
djwolford
Well I'll try to make the story short. More or less, whenever you work your muscles, you're causing microscopic tears in your muscle tissues. The point of working out is generally to try to get those muscles built back stronger and/or larger and/or denser than before. You need recovery time(Usually around 48 hours, depending on genetics, nutrition, age, and a whole list of other things.) for your body to rebuild those tissues effectively. If you don't give your body enough time to rebuild, you risk overtraining, which can cause a whole list of problems including loss of strength, loss of muscle mass, fatigue, headaches, appetite loss, lack of motivation, etc.