Objective The aim of this research is to study the level and the degree of influence of speed as a determining biomechanical parameter to achieve the best performance of vertical jump in attacking volleyball players during the various stages of execution of the smash. Materials and methods As part of our research, we chose nine volleyball attackers cadets boys (average age: 16.55 ± 0.53 years, average size: 181.11 ± 9.74 cm, average body weight: 69.70 ± 10.77 kg), including one taken as a reference sample. We measured, determined and calculated for each player a certain number of kinematic and dynamic parameters and this through the analysis of video sequences, carried out using Kinovea, Origin and Deadline softwares. The statistical analysis of the results allowed us to know the level and the degree of influence of the components of speed (the maximum speed reached during momentum, the speed of extension) as well as the main biomechanical parameters depending on the latter (the average vertical support force and the average inertial arm force) influencing the vertical jump. Results Our study highlights the level and the degree of influence of the components of speed during the various stages of execution of the smash in order to achieve the best vertical jump possible. Thus, despite the nonexistence of a correlation between the maximum speed reached during the momentum and the vertical jump, the fact remains that this speed makes it possible to determine the average inertial arm strength, a component of the average vertical arm strength which is correlated with vertical expansion (R = 0.819, R2 adjusted = 67 %, P < 0.01). The extension speed (R = 0.999, R2 adjusted = 99.66 %, P < 0.001) and the average vertical down-force (R = 0.925, R2 adjusted = 83.42 %, P < 0.001) are closely and positively correlated with the vertical trigger. The speed remains the most decisive parameter for achieving the best performance in vertical jump when playing volleyball smash. Its influence is either direct during the extension phase (extension speed) or indirect during the call stage (maximum momentum speed). The average vertical arm strength can be improved by increasing the maximum momentum which ameliorates the average inertial arm strength. The speed of extension represents the paramount parameter for obtaining the best value of the vertical jump among all the attacking volleyball players of the study sample and contributes enormously to the determination of the average vertical support force. The latter is the second parameter most correlated with vertical expansion.
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