A long jumper runs before jumping because he

A long jumper runs before jumping primarily to gain momentum. Momentum is the product of mass and velocity; by sprinting during the approach run, the athlete increases their horizontal velocity, thereby maximizing their momentum at the point of takeoff [t1][t8]. This accumulated momentum is crucial because it allows the jumper to maintain a higher horizontal speed while airborne, which directly translates into covering a greater horizontal distance [t1][t6]. While the athlete also gains kinetic energy, the specific mechanical advantage in jumping sports is often described through the lens of momentum and inertia of motion, which helps the body continue moving forward after the feet leave the ground [t1]. The run-up allows the athlete to reach a peak velocity that can be partially converted into vertical lift while preserving enough horizontal drive to achieve maximum range [t2][t6].

Sources

1. [1] https://researchonline.ljmu.ac.uk/id/eprint/5069/1/313164.pdf