The day after working out should be a day of rest for the worked muscle group as much as possible. Your training will have caused micro-tears in the muscle fiber, resulting in fatigued muscles and muscle strain. To build the muscle back, rest is needed. You should also be taking in 20-30 grams of protein every 3 hours the day after your workout. This will supply your worked muscle group with the amino acids it needs to rebuild the damaged muscle tissue.