Working on particular muscle groups can be achieved by doing specific exercises that focus on these muscle groups. In fitness gyms exercises usually involve using free weights or machines. For beginners it is better to start with machines because they ensure proper movement of muscles that allows getting most efficient muscle stimulation. Later when some growth has been reached and proper movements learned free weights can be involved for more natural movements that will also involve other muscles that were not involved much during machine exercise movements.

Learning how to build up muscle properly requires analyzing closely progress of muscle growth as this is essential part of mass building. Stressing out each muscle group with particular training method eventually reaches saturation point which slows down growth process significantly and at this point there is a need to change to different training method to make further growth possible. This happens because muscles are adapting over time to particular stress and to trigger further growth it should be put under different kind of stress.

Such variation of different stress can be achieved by training method shifting that involves doing different amount of exercise sets and reps in each set for particular exercise. Recommended approach is to do one set of 10-12 reps for each exercise in beginning stages of muscle building which will allow doing most possible exercises within 60-90 minutes of training session that is optimal recommended time for workouts. Such approach is required for general muscle base strengthening before going into more intensive workout routines.

After few months of general training and analyzing of muscle growth progress that will slow down at this point shifting to 3-4 sets of 10-12 repetitions is advised. Less exercises will be involved so selection should focus on main muscle groups for legs, chest, back and arms. When another slowdown in growth is reached then maximum strength training can be performed which involves only 3-4 repetitions using maximum weight that can be lifted but for more sets like 6-10 depending on individual case and progress pace.