OLD SCHOOL One Muscle Group A Day Training

This system of training is for natural intermediate and advanced bodybuilders only.
It is a well established fact that the body needs anywhere from 24 to as many as 72 hours of total rest and recuperative sleep between workouts for muscle restoration and growth to take place.
During a particular workout session you don't have to save your energy for other muscle groups, so it is much easier to motivate yourself to train with more intensity.