Sidney Licht, Music in Medicine (1946)
“ Johnson [51] believed that the strength of muscle contraction increases with the intensity and pitch of accompanying music, and that the point of fatigue is postponed when calisthenics is given to music, but that unsteadiness might result from variation in the musical score. Anything that will divert the attention from the proper execution of the exercise is a hindrance, and music should not be used until the exercise has become thoroughly mastered. Once the exercise has become second nature, music becomes very useful because it acts as a stimulus and adds interest. ”
