Efficiently training for increased muscle size involves manipulating just a few of the training variables. First, the number of repetitions performed is typically in the range of 8 to 12. Second, the movement speed during training is normally rather slow, in the range of two to three seconds to lift the weight and three to four seconds to lower the weight. In addition, exercises that involve movement at multiple joints and, as a result, a great amount of muscle mass, are emphasized over single-joint exercises that recruit a smaller amount of muscle mass.