(29) ACCURACY OF A LINEAR POWER TRANSDUCER FOR MEASURING COUNTER MOVEMENT JUMP PERFORMANCE IN ELITE FEMALE VOLLEYBALL PLAYERS

Purpose: The countermovement jump (CMJ) has become a common assessment for evaluating force and power output of the lower extremity. The evaluation of these performance characteristics is critical in athletic populations, such as female volleyball players. The purpose of this study was to compare the assessment of vertical jump performance between a linear power transducer (LPT) and a force plate system (FPS). Methods: Sixteen Division I female volleyball players (age = 19.4 ± 1.5 years, height = 176.2 ± 10.6 cm, weight = 71.5 ± 11.1 kg) participated in this study. Each participant performed two CMJ familiarization attempts, followed by three trials that were simultaneously measured with an LPT and an FPS, with 1-minute rest periods between trials. The tether from the LPT raised vertically and attached to a belt that was securely fit around the waist of each participant. Proper technique of the CMJ attempts were verified through observation by two Certified Strength and Conditioning Specialists. The peak height value (cm) from the three trials obtained via FPS (as the criterion) was recorded and analyzed. Results: The mean ± SD values for peak jump height was 48.2 ± 4.4 cm for the LPT and 36.2 ± 3.9 cm for the FPS, which was significantly different (p < 0.001). The CMJ value from LPT was significantly correlated (r = 0.89, p < 0.001) to FPS and showed a standard error of estimate (SEE) of ± 1.86 cm. Limits of agreement procedures showed a 95% confidence interval (constant error ± 1.96 SD) of 12.1 ± 4.1 cm.Conclusions: Compared to the criterion FPS, the LPT provided significantly higher mean values, yet displayed a strong correlation, small SEE value, and tight LOA when used to test CMJ in elite female volleyball players. Practical Applications: Practitioners who work with elite female volleyball players should consider the results of the study when testing CMJ with an LPT, as according to the results, it may consistently provide higher CMJ values compared to an FPS. However, due to the relatively small range of individual error, applying a correction factor may reduce the mean error associated with the LPT. Acknowledgements: none