Playing the piano requires activation of muscles of the upper limbs, neck and back. to play the keys, the fingers must generate rapid, small movements that vary in force generation to play the keys sometimes very hard (larger amounts of force) and sometimes very soft (very little amounts of force), and everything in between. the elbow flexors hold the elbow joint at the same comfortable angle throughout the duration of play, which can last several hours. additionally, the player must also sit upright at the piano bench for these long durations without the back or neck muscles fatiguing. for piano playing, which muscles would have the fewest fibers controlled by each motor neuron