|Title of the paper:||Human movement variability in Volleyball spike approach between zone II and zone IV with and without ball|
|Authors:||Catala, J., Fernández-Valdés, B., Moras, G.|
|Institution:||National Institute of Physical Education of Catalonia
The game of volleyball is characterized by short and explosive movement patterns. A volleyball match consists of different executions of specific technical skills of Volleyball such as, defense, blocking and attacking. Attack seems to be the most important ability to win in youth and senior games.
The variability of the players must be understood and perceived during the execution of the attack within the variables process (angular positioning of the joints, acceleration or contraction of the muscles) (1). In addition, in any time series, representing an output variable of the system, entropy is a measure of its uncertainty. From this perspective, volleyball spike approach movement (SM) oscillations can be evaluated, like any other time series, through entropy calculation techniques (2). The aim of this study was to identify the differences in human movement variability during SM from zone II and IV with and without the ball.
One WIMU(Realtrack systems) was located below L3 to forty eight female first division players (Mean ±SD: Age17,56±3,60; Height: 1,77±0,05; weight: 67,78±7,09) who performed SM in both conditions (with ball and without ball)per each area (zone IV and zone II). The players performed a standardized warm-up after which they realized in random order four sets of six SM, two of them with ball and two of them without ball, in two sessions on different days. The human movement variability was calculated with Approximative Entropy (ApEn) and Sample Entropy (SampEn) through the modulus of acceleration.
The ApEn and SampEn response variables were analysed using a Mixed linear Model, where SM with or without ball is the main variable explanatory (SMball) and, different zones as a secondary variable explanatory (SMzone). The means in SampEn were, without ball (M: zIV=0,062; zII=0,062) and with ball (M: zIV=0,089; zII=0,089), No significant differences were found in SMzone (p=0,6801); Significant differences were found in SMball (p?0,001). Also in ApEn the means were, without ball (M: zIV=0,144; zII=0,144) and with ball (M: zIV=0,165; zII=0,163), Significant differences were found in SMball (p?0,001) but not in SMzone (p=0,9485).
Movement variability of the players performing SM is not affected if it is done on the different sides of the volleyball court (zone II and zone IV), however it is increased if the SM is performed with ball.
1. Dias G et al. (2014), 2. Stergiou N. (2016)
|Topic:||Training and Testing|