# Evaluation of Lower Extremities Power, Movement, Position and Effectiveness in Volleyball
## 4 Discussion
When analyzing the height of jumps (JH), the best average values were achieved by the receiving players (45.35 cm) with 67 jumps, while the lowest average values were achieved by libero jumpers (31.98 cm) with 41 jumps. In the test of power (P), which is of interest to the authors, the highest level was found in the receiving players (50.84 W/kg) and then the setter (44.80 W/kg), the middle (43.47 W/kg) and, the most interesting, the libero players, who obtained a better result (42.75 W/kg) than the attackers (41.65 W/kg). Significant differences were found in all movement parameters in isolated conditions described by the OptoJump test methodology. The average values of the pace of jumps (Pace) werevery similar in the studied group of players, reaching values in the range (1.1-1.3 step/s). The TStance parameter achieved the greatest differences (tilts/displacements/shifts) in attacking players, reaching the value (0.38 cm). Walking Point X turned out to be the most diverse indicator in the studied group of movement parameters, and the highest mean values of tilts occurred in the receiving (\(-\)16.34 cm) and middle (\(-\)13.42 cm) players. The highest values of the Step Width index (foot spacing, step width) were achieved by setters (30.32 cm), middle (28.19 cm) and attackers (28.06 cm), the average ones for receivers (25.26 cm), and the lowest for libero (19.39 cm). This relationship may be related to the total height of the body and the length of the lower extremity [28]. Competitors who achieve the highest jump height are characterized by a large number of tilts and, at the same time, average SW values. In the opinion of the authors of the research, a greater value of step width may determine the extent or amplitude of the player's displacements in the jumps during the OptoJump test. The [PERSON]'s test (Tables 5, 6) used in the analysis confirmed the statistical significance of all jump parameters and movement parameters, excluding Walking Point X. Comparison of the power level with the reception rates shows a high correlation level of 0.677 for the GPF Reception index and 0.679 for the EF Reception index. This result indicates a high dependence between the effectiveness of receiving the serve and the power generated by the player. The research also shows a high correlation between the serve and power indices. The values of GPF Serve 0.522 and EF Serve 0.560 achieve a high level of correlation, indicating a significant dependence between the serve and the power (Figure 3). According to Figure 1, the increase in the value of the player's flight time increases his share of scoring points for the team. The study by [PERSON] et al. [29] investigated the influence of strength and power training on volleyball-specific skills like passing, attacking, and blocking. Their results showed significant improvements in strength measures and skill performance, such as an increased probability of a 'kill' attack (\(p>0.99\)). Our studies focus more on positional performance differences. [PERSON] et al. indicate that strength and power training significantly enhance the majority of volleyball skills, which is consistent with the findings of our study. The results of the study by [PERSON] et al. [30] emphasize the significance of specific physical and technical performance elements in volleyball. The results in our work partly focus on the lower limb power and its influence on player effectiveness in different playing positions, demonstrating how factors like jump height and flight time--reaching values of 35-40 cm and up to 600 ms for outside hitters and middle blockers--correlate with successful performance. On the other hand, [PERSON] et al. examined the serving skill and its performance across genders, revealing that men predominantly use the power jump serve (PJS) (75.4%). Both studies demonstrate that performance metrics are highly dependent on the player's role and the technical actions required, such as serving zones and directions. For instance, [PERSON] et al.