The correlation between two unilateral jumps and change of direction in young soccer players

Abstract: Background: A lot of previous research have studied the correlation between bilateral jumps with performance in change of direction (COD) even though COD occurs unilateral. Only a few researches have studied the relationship between COD and unilateral jumps but the results are conflicting. Neither of these have studied the correlation between COD, measured with the Zigzag agility test, and both unilateral horizontal jumps (UHJ) and unilateral lateral jumps (ULJ) among young soccer players.  Aim: The aim was to study the magnitude of the correlation between UHJ and the Zigzag agility test and between ULJ and the Zigzag agility test among young male soccer players.  Method: Thirty young male soccer players between 17-19 years were tested in a Zigzag agility test and two different jumps (UHJ and ULJ). The time of the Zigzag agility test was measured in seconds and the length of the two jumps in meters. Everything were tested during one test session. Pearson correlation coefficient was used to calculate the relationships between UHJ, ULJ and the Zigzag agility test. Following guidelines were used to determine the magnitude of the correlation: r below -0.29 for a small correlation, r= -0.30 to -0.49 for a medium correlation and r -0.50 to -1.0 for a strong correlation.    Results: Small correlation were found between UHJ and the Zigzag agility test (r= -0.028) and as well as between ULJ the Zigzag agility test (r= -0.27). The mean value (SD±) was 6.41s (0.18) for the Zigzag agility test, 1.87m (0.15) for UHJ and 1.65m (0.13) for ULJ.  Conclusion: The findings of this study showed that both UHJ and ULJ had small correlations with the Zigzag agility test as a measurement of COD performance, with a slightly higher correlation for the ULJ. This means that unilateral jumps and COD performance probably are two different skills and should be trained in different ways. Not much research has been done in this area and the results concerning the correlation between COD and unilateral jumps are still mixed. More research is needed to declare the relationship with unilateral jumps and COD performance. Interesting for the further research would also be to involve other factors such as running technique and straight sprinting to determine the importance of each factor.