Health and Fitness

Rest for muscle growth:
One of the best pieces of exercise advice is to understand that your muscles grow when you’re resting not training. That's right; you don't actually get bigger and stronger when you're in the gym. It's what you do after your workout that's the real key to muscle growth. If you don't let your muscles recover correctly, you're body will become over trained and it will be in a state of constant "catch up". This is far from the ideal state that you want your body in. What you want is to truly prime your body for your next workout and give it enough rest and recuperation to fully optimize your training.

More at: http://www.fitnessattitudes.com/strenghttraining.html