Vertical Jump Height Prediction with Upper-limb Counter-movement, Pre-jump Knee-Flexion and Approaching Distance in Volleyball Players

Abstract

BACKGROUND: Vertical jump height is one of the key elements to provide a powerful spike in volleyball competitions. Vertical jump is reported to be effective with the existence of the arm swing angle, countermovement jumps and approaching distance in extreme conditions. The intensity of the existed factors remains unknown. PURPOSE: To investigate the relationship between vertical jump height, upper limb counter-movement, pre-jump knee-flexion, and approaching distance. Also, this study aims at establishing a prediction model of peak vertical jump height in order to enhance jump performance for volleyball players in real sport situation. METHODS: A total of 20 experienced adult male volleyball players were recruited to undergo an experiment in the Polytechnic University. Subjects were asked to perform a series of maximal vertical jump tests with different combinations of upper limb counter-movement, pre-jump knee-flexion, and approaching distance. The joint kinematics were measured by using 16 inertia measurement units with a Noraxon marker-less motion tracking system. Force plate and a VICON motion capture system were used to collect synchronized kinetic data. The maximum vertical jump height was recorded by a vertical height meter. The received data was analysed with regularized least-squared regression by using MATLAB. RESULT: A significant correlation was found between the vertical jump height and the force, the right knee flexion-extension, right shoulder flexion-extension, the flexion-extension velocity of left shoulder, the flexion-extension velocity of right shoulder, BMI and the upper limb length. The Root Mean Square Error (RMSE) of using lasso plot equal to 7.87 cm. Results of the study suggest the importance of optimal spike jump technique to achieve a maximum vertical jump height and provide a significant reference for developing a flex sensor to observe and enhance the vertical jump height in practices. CONCLUSION: Force makes the greatest contribution to the vertical jump height. Increasing right shoulder flexion and its angular velocity can be a possible solution to enhance the vertical jump height as the can be changed immediately in real sport situation. Changing the force and knee angle may not be effective when the players decide the jump position in real sport situation.