Sachs was very meticulous in his research on the movements of "stretch dance". He first discovered: "The kicking certainly does not only represent rhythmic movements, but the heavy kicking represents an extremely strong movement. Or the prelude to a successful aerialist's graceful bounce from the ground in defiance of gravity." He also found: "Bending the knee is also a global action. There are two forms, one is a static posture, and the other is rhythmic movement. The recovery movement of semi-relaxed joints seems to be the main feature..." In addition to In addition, he also pointed out that "the pinnacle of stretch dance is the vertical jump"; pointed out that "closely related to the vertical jump with unrestrained movements is the lift"; pointed out that "a gentler form of upward stretching" It is to raise the knees - quickly lift the thighs in turn"; pointed out that "the characteristic of toe dance is to stretch upward, the human body does not leave the ground, and the muscles are relaxed as much as possible"...