There are numerous approaches you can take to gaining muscle size and strength. If you’re just getting started in the weight room, a study published in The Journal of Sports Medicine and Physical Fitness offers interesting insight into workout program planning.
Thirty untrained men in the early 20s took part in a 10-week program that hit each muscle group once or twice a week. All subjects performed the same volume of training regardless of which group they were assigned to.
At the end of the program, the muscle thickness of elbow flexors increased an average of 1.73 mm in the once weekly group and 2.31 mm for subjects in the twice weekly group. Subjects in the twice weekly group also experienced greater increases in strength.