Takeoff

Takeoff is the brief action in which an athlete pushes against the ground to begin a jump. Its force and timing shape the jump’s height, distance, and direction.

Ground reaction force: The force a surface exerts on a body in contact with it. The ground’s upward force changes the athlete’s momentum during the push.
Newton's laws of motion: Three principles relating an object's motion to forces acting on it. They explain why pushing against the ground accelerates the athlete upward.
Vertical jump: A jump in which performance is measured by the height reached or the body's vertical displacement. Its takeoff aims to maximize upward velocity.
Countermovement jump: A vertical jump preceded by a downward movement before the athlete pushes upward. Its preparatory dip contrasts with takeoffs that begin from a static position.
Impulse: The change in momentum produced by a force acting over time. Takeoff impulse determines the athlete’s velocity at the instant contact ends.
Center of mass: The point representing the weighted average position of a body's mass. Its velocity at takeoff predicts the body’s subsequent flight path.
Long jump: A track-and-field event in which an athlete jumps for maximum horizontal distance from a board. Its takeoff balances horizontal speed with enough upward lift for flight.
Squat jump: A vertical jump initiated from a stationary squat without a preceding countermovement. It isolates propulsion without the rapid prestretch used in many takeoffs.
Stretch-shortening cycle: A muscle action sequence in which rapid lengthening precedes shortening and can enhance force output. A quick countermovement can store and return energy during takeoff.
Momentum: A body's mass multiplied by its velocity. The takeoff push changes momentum that persists after the feet leave the ground.

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