A correlation study between unilateral countermovent jumps, unilateral drop jumps and different sprint distances

Abstract: Background: Sprinting and jumping is an important physical part of soccer. Games are often won or lost cause of this two factors. Also the ability to sprint, how often you can sprint and how well you can sprint late in a game is what differ between the absolute world class players and other top class players. A players ability to produce power affects the players ability to sprint and jump. Power production can be tested as well as trained with plyometric exercises. Two plyometric exercises commonly used to test players abilities are the counter movement jump and the drop jump which can be performed either unilateral or bilateral. Relationships between bilateral counter movement jump and sprint is well established. But the relationship between unilateral countermovement jumps and unilateral drop jumps and sprint are not as well examined. Aim:  The aim of this study is to examine which one of the two tests, unilateral CMJ and unilateral DJ, that have the highest correlation with short sprinting. Method: 14 male junior soccer players playing on a high national junior level participated in this study. Two blocks of sprints was performed, 0-15 m and 0-30 m with time measured on every 5 m. Two trials of unilateral countermovement jumps and unilateral dropjumps was performed on the subjects dominant leg. Spearman’s two-tailed correlation test was used and a value of > ±0.6 was considered to be a strong correlation. Results: 10 subjects attended both the sprint and jump trials. No strong correlations was found. The highest relationships was that between unilateral counter movement jump and 0-30 m sprint (rs = -0,30) and that between unilateral drop jump and time between 20-30 m sprint (rs = 0,30). No strong correlations was found. Conclusion: The results showed no strong relationships between the jumps and any of the sprint distances. Therefore neither of the jumps can be said to better predict sprint performance on any distances up to 30 m. Neither can the results from this study be of use to recommend any of the jumps before the other in training as plyometric exercises to improve performance on the acceleration phase or the top-speed phase.