Dr. Hab., Associate Professor N.V. Lutkova¹
Dr. Hab., Professor Yu.M. Makarov¹
PhD, Associate Professor I.A. Panchenko²
D.A. Vasiliev^2
1Lesgaft National State University of Physical Education, Sport and Health, Saint Petersburg
²Saint-Petersburg Mining University, Saint Petersburg

Objective of the study is to improve the effectiveness of serving among skilled volleyball players by developing their ability to accurately differentiate muscle effort through the use of specialised exercise blocks.
Methods and structure of the study. Serve effectiveness indicators were assessed based on competition data: for the main team, Dynamo-LO, in the Russian Men's Championship, and for the farm club, Dynamo-LO-2, in the Russian Youth League. Parameters characterising the technique, situational conditions and direction of serves by qualified volleyball players were analysed. Ten games of the leading teams were processed using professional Data Volley 4Pro software. The initial level of preparedness of the athletes was determined during pedagogical testing. The ability to differentiate muscle effort was assessed using a DK-140 hand dynamometer, which allowed the accuracy of reproduction of specified force levels (25%, 50%, 75% of maximum effort) to be measured. The experimental part included specialised exercise blocks aimed at developing arm muscle strength and strength differentiation sensitivity. Twenty-four qualified volleyball players took part in the study.
Results and conclusions. It was found that qualified volleyball players of the Dynamo-LO 2 team perform planning serves more often than power serves during competitive activities. The indicators of the skilled volleyball players of the Dynamo-LO-2 team have statistically significant differences from the indicators of the Dynamo-LO team players in all six analysed characteristics. It has been found that it is advisable to identify four narrowly focused sets of tasks for developing the ability to differentiate muscle effort (with TRX loops, with expanders, with stuffed balls, with volleyballs). Qualified volleyball players of the Dynamo-LO-2 team showed positive dynamics in the number of planned and power serves, the effectiveness of their execution, and a decrease in the number of errors during their execution.

Keywords: differentiation of muscle efforts, means, serve, qualified volleyball players.

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