Horizontal and vertical jump assessment: reliability, symmetry, discriminative and predictive ability

Objectives: The purpose of this study was to: (1) establish the reliability of a new unilateral concentric only horizontal jump assessment (HSJ) then compare the reliability of this test to other types of unilateral vertical and horizontal jumps; (2) compare the tests to whether they differ in their ability to determine limb asymmetries; and (3) investigate the relationship between these jumps and sprint running. Methods: Eighteen sportsmen performed unilateral jump assessments involving the horizontal squat jump, horizontal countermovement jump, horizontal repetitive jump, vertical squat jump, vertical countermovement jump, and vertical repetitive jump. Results: Reliability for the new test was found to be the equal if not better than the other more established tests of leg power, with the within trial variation (CV = 1.1-1.9%) and test-retest reliability (ICC = 0.89-0.90). None of the tests were found to have greater discriminative ability in determining limb asymmetries. Stretch shorten cycle enhancement was greater in the vertical tests (12.1%) compared to the horizontal tests (1.3%). Horizontal jump assessments (r = -0.73 to -0.86) were found better predictors of 20-m sprint performance than the vertical assessments (r = -0.52 to -0.73), with the horizontal cyclic assessment being the best predictor (r = -0.86). Conclusion: Horizontal leg power assessment appears an inexpensive, easy to administer, reliable and valid method to assess unilateral leg power. (c) 2005 Published by Elsevier Ltd.