EXPLOSIVE STRENGTH, ARM SWING JUMP CONTRIBUTION AND ECCENTRIC UTILIZATION RATIO IN YOUTH AND JUNIOR FEMALE VOLLEYBALL PLAYERS

Abstract

Vertical jumps are a defying predictor of performance in sports that require explosive action. Objectives of the present study are: 1) to evaluate anthropometric characteristics (height, body mass and BMI), explosive strength (squat jump, countermovement jump and countermovement jump with an arm-swing) and kinematic parameters (the arm swing jump contribution and the eccentric utilization ratio) in female volleyball players; and 2) to compare assessed parameters between youth and junior players. Thirty participants, players that are part of Macedonian Youth (N=15) and Junior (N=15) National Teams, aged 13-18 years, were included in the study. Anthropometric characteristics were measured according to the WorldHealth Organization manual, explosive strength was assessed with the Optojump system, and kinematic parameters were calculated as proposed by Abdel-Rahman (2013). SPSS 23 statistical package was used to perform statistical analysis. Normality of data distribution was tested by K-S test, Skewness and Kurtosis values. Appropriate statistical methods were used to calculate descriptive statistical parameters, and t-test was applied to determine the significance of the difference between youth and junior players. In addition, Cohen’s d was applied to calculate the effect size. No statistically significant differences were found between youth and junior players in parameters assessed. Coaches should take in consideration anthropometric and morphological characteristics of the players during the selection process, and work more in a direction of motor abilities development and improvement of technical skills, especially in pioneer and youth categories, instead of putting the main emphasis on player specialization at early age.