This crouching action is usually performed quickly and referred to as a counter-movement: the rapid bending of the legs and the movement of the arms to the person's sides constitute the counter-movement to the actual jumps range of movement. The counter-movement and the jump collectively are referred to as a counter-movement jump (CMJ).
This crouching action is typically executed swiftly and is called a counter-movement: the quick bending of the legs and the movement of the arms to the sides represents the counter-movement relative to the actual jump's range of motion. The counter-movement and the jump together are known as a counter-movement jump (CMJ).