Abstract
Purpose: The main objective of this study was to evaluate the level of muscle strength by using isokinetic and isometric measurements—more specifically, the force ratio between the knee flexors and extensors (values of the torques). Methods: An experimental group of elite volleyball players (n = 14) were compared to a control group (n = 14) of healthy non-athletes of comparable ages. Torque measurements were obtained under three concentric conditions (angular velocities of 60 °/s, 180 °/s, and 300 °/s) and one static condition by utilizing the Biodex System 3. Results: In all trials, the volleyball players achieved significantly higher peak torque (PT) values for both the extensors and flexors (p < 0.05) than those of the control group. However, the strength ratio of the flexors and extensors (H/Q) in the experimental group was only 83% of the standard reported in the literature. The most developed and dominating muscles in the knee joints of the volleyball players were the extensors, which accounted for the low strength ratio and dynamic instability of this joint. Conclusion: Based on a proper assessment of the strength ratio of the knee flexors and extensors, properly selected and implemented resistance training can improve the maximum strength and power production and reduce the incidence of injuries in volleyball.
Highlights
The results of the experiments with the twenty-eight participants who were divided into two groups—fourteen volleyball players and fourteen physical education students—
The somatic parameters within the experimental group and the control group—given as arithmetic means and standard deviations—had the following values, respectively: height, 195.7 (±6.2) and 178.7 (± 6.7) cm; mass, 87.8 (±6.9) and 73.4 (±8.9) kg; BMI, 22.9 (±1.3) kg/m2, which was similar in both groups
The volleyball players were taller and heavier than the participants from the control group by 8.7% and 16.4%, respectively. This can be explained by the fact that the volleyball players were a carefully selected group of males with respect to height
Summary
Volleyball is a non-contact team sport that requires players to alternately perform high-intensity actions involving passing a ball and scoring points against the opposing team on their court [1]. The ball-passing actions involve jumping activities that are performed near the net (e.g., sets, spikes, and blocks) and a jumping serve that is executed at one end of the court. These movement structures are critical for executing such actions and have a great impact on the final game performance [2]. Additional factors for success in the game of volleyball are the quality of the jumps performed (vertical jump height), the technique of passing the ball, and the players’ anthropometry (height of the body)
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