TAKE-OFF FORCES AND IMPULSES IN THE LONG JUMP

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A series of jumps by an experienced female athlete were recorded with a force platform and a high-speed video camera. We obtained a wide range of run-up velocities by using direct intervention to set the length of the athlete’s run-up. In all jumps the horizontal take-off force was predominantly a backwards braking force and so the athlete’s horizontal velocity was substantially reduced during the take-off. The athlete’s breaking impulse increased with increasing run-up velocity, but not so much as to negate the increase in run-up velocity. The optimum long jump take-off technique is a compromise between the conflicting desires of generating vertical impulse and minimising the horizontal braking impulse. We currently have no firm recommendation as to the usefulness of a force platform in improving an athlete’s take-off technique.