(1) COUNTERMOVEMENT JUMP PERFORMANCE AND THE IMPACT OF A COMPETITIVE VOLLEYBALL SEASON

Purpose: To examine in-season changes in countermovement jump (CMJ) force-time characteristics in National Collegiate Athletic Association (NCAA) Division III female volleyball players.

Methods: 17 NCAA Division III female volleyball athletes (age: 19.6 ± 1.0 years, body mass: 70.6 ± 11.3 kg, height: 174.0 ± 6.5 cm) completed two CMJ testing sessions during the competitive season as part of a long-term athlete monitoring program. The first testing session took place in the first week of the season while the second took place during the final week. During each testing session, each subject completed a standardized dynamic warm-up before performing two maximal effort CMJ trials. Each CMJ trial was performed on dual force plates and the force-time data were used to calculate jump height and propulsion mean force, velocity, and power. The average performance between CMJ trials during each testing session were used for statistical comparison. A series of paired-samples t-tests were used to examine the in-season changes in CMJ force-time characteristics. In addition, Hedge’s g effect sizes were calculated to determine the magnitude of change between testing sessions.

Results: The descriptive data for the CMJ performances during each testing session and the Hedge’s g effect sizes are displayed in Table 1. There were statistically significant decreases in CMJ height (p = 0.037) and mean velocity (p = 0.022). In contrast, the differences between beginning and end of season CMJ mean force (p = 0.686) and mean power (p = 0.079) were not statistically significant. The changes in CMJ height, mean velocity, and mean power were small while the change in mean force was trivial.

Conclusions: There was a decrease in CMJ height, mean force, mean velocity, and mean power from the beginning to the end of the competitive season. However, the changes in performance were trivial to small indicating that they may not be practically meaningful. PRACTICAL APPLICATIONS: Consistent in-season CMJ testing may provide strength and conditioning practitioners with some insight into how a team is adapting to competition stress. The current results indicate that the volleyball team on average, showed small decreases in their explosive strength characteristics as indicated by their changes in jump height, mean velocity, and mean power. However, the team was also able to maintain their propulsive mean force characteristics, demonstrating a maintenance of strength. Although the current study examined the changes in team performance, it is important to monitor individual player changes as well. In doing so, practitioners may be able to prescribe effective training stimuli to maintain or improve performance characteristics throughout a competitive season.

 

Acknowledgements: None