Relationships between force-time curve variables and jump height during countermovement jumps in young elite volleyball players

Background: The importance of vertical jumps has been extensively recognised in sports. Furthermore, the main indicator of success in vertical jumps is the attained height, however, there is lack of knowledge on how the eccentric and concentric force-time curve variables affect the jump height. Objective: The objective of this study was to assess the relationships between eccentric and concentric variables of the force-time curve and jump height in youth volleyball players. Methods: Twelve elite volleyball players (male, Iranian national youth volleyball players, 17 ± 0.7 years) have participated in this study. The correlations between the force-time variables, including the peak force, relative peak force, peak power, average power, relative peak power, peak velocity, and modified reactive strength index, of the eccentric and concentric phases and jump height have been assessed based on Pearson's correlation coefficient. Results: Results showed that the average power (r = .70, p = .034), relative peak power (r = .75, p = .029) and peak velocity (r = .98, p = .004) of the concentric phase and modified reactive strength index (r = .83, p = .014) significantly correlated with the jump height. Conclusions: Relative peak power and average power of the concentric phase are shown to affect jump height in young volleyball players, whereby the vertical jump is their integral part