Relationship between strength qualities and performance in standing and run-up vertical jumps.

BACKGROUND: The purpose of this investigation was to determine the relationships between the strength qualities of the leg extensor musculature and performance in vertical jumps (VJ) performed from a standing position and a run-up.
METHODS: Twenty-nine males with experience in jumping activities were tested for vertical jumping capacities with a standing VJ (double leg takeoff) and run-up jumps from a 1, 3, 5 and 7 stride approach (single leg takeoff). The speed-strength and maximum strength qualities of the leg extensors were assessed by tests involving concentric, stretch-shortening cycle (SSC) and isometric muscular actions. Pearson's correlations and stepwise multiple regression was performed to describe the relationships with jumping performance.
RESULTS: The speed-strength tests correlated significantly with both jump types (r = 0.55-0.82), but maximum strength did not. A drop jump test considered to measure reactive strength correlated more strongly with the run-up jump than the standing VJ. The standing VJ was best predicted by a low stretch load SSC test, whereas the run-up jump was best predicted by a model that also including the test of reactive strength.
CONCLUSION: The role of maximum strength in jumping performance was not clear but speed-strength qualities were considered important. It was concluded that reactive strength is relatively more important for jumping from a run-up than for the standing VJ, and this should be reflected by appropriate training methods and test protocols for the assessment of athletes who jump.