Biomechanical model characteristics of attacking hit performance in volleyball

Methods of strain measurement, optoelectronic recording and electro-myography were used to study the determining biomechanical model characteristics of attacking hit performance in volleyball. We saw longer average electrical activity of muscles in the preparatory phase as compared to the main phase. It means that the player during the attacking hit spends more time on the perception of elements of the task content and solution than on the hit, and the dynamic stereotype in the main phase is more stable than in the preliminary phase. From the physiological point of view, this is due to the fact that the longer the person makes the move, the more it is subjected to correction. This proves by the consistent display of electrical activity in the muscles of the athlete. When performing the accurate attacking hit, the highest coefficient of electrical activity parameters variation is observed in the main phase of movement. Consequently, the internal mechanisms of the cognitive program of the game action form in the preparatory phase and are implemented in the main phase through the motor program under control of the higher parts of the central nervous system. The perception of the environment of the game in solving tactical problems is determined by fixing the attention of athletes on objects in search for the problem and understanding its essence. The priority direction of the symmetry axis is allocated as the are for searching the target. Performance of techniques in sports connected with accurate hits of the ball in the target is characterized by consecutive inclusion in the movement of the "working" muscles providing realization of the target-hitting function, and also relative stability of indicators of work of these muscles by amplitude, time and order of their inclusion in work; relative stability of kinematic characteristics of movement: time and values of components of support reaction, angle sizes, angle speeds of body links, etc. At the same time performance of techniques in sports that do not provide accurate hits of the ball is characterized by lack of synchronization in consecutive inclusion of "working" muscles (late inclusion, disorder in inclusion, etc.) and also high variability of indicators of work of these muscles by amplitude, time and an inclusion order; high variability of kinematic characteristics of movement by all indicators of reaction of support and angle values; increase in time of reaction of support in all components (to Fx, Fy, Fz) and increase in values of indicators of horizontal, forward and back elements of support reaction up to 12% (rather accurate attempts). Thus, the measure of technical and tactical skills of athletes in sports associated with the successful implementation of tactical decisions can serve as a performance technique at optimum stability of the kinematic characteristics (the form of movement), and certain sequences included in the necessary work of muscles and stability of their performance (the mechanism of movement).

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