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. It is difficult to move rhythmically out of time with the music. Most popular recorded music is in a tempo too rapid to be satisfactory for calisthenics. For this reason live music is far more satisfactory as an accompaniment, and a single instrument, preferably the piano, is most suited to it. The pianist can take the cue from the exercise leader for tempo. The piano should be played in a steady unvarying rhythmic style. Well known tunes and folk-songs should be used. The piano must be played loud and with strongly accentuated rhythm. Hulbert[49] relied largely on waltzes, marches, and folk-songs played slowly. The songs he used to advantage include “Believe Me If All Those Endearing Young Charms,” “Bonnie Dundee” and “O No, John.” In this country such songs as “The Skater’s Waltz” and “There’s a Long, Long Trail A Winding” are popular for this use. Ideally, live music should be used to accompany exercise so that the tempo can be readily adjusted to the speed of the participants. If commercial recordings must be used they should be carefully selected to rule out those containing vocal or other interludes which break up the continuity of the rhythmic pattern, and the operator should silence the machine between successive exercises. The use of music during exercises will depend upon the value attached to it by the instructor. Some may find the time and trouble required unwarranted. Others may find in it a way to get better co-operation or increased pleasure. There is one use of music in connection with group exercise which is strongly recommended. Preceding the actual period of exercise the playing of a stirring march, while the participants march to their places of assembly, acts as a stimulant and conditioner for the activity to follow. REMEDIAL EXERCISE AND DANCING