(36) ACCURACY OF A SMARTPHONE APPLICATION 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 extremities. The evaluation of these performance characteristics is critical in athletic populations, such as volleyball players. The purpose of this study was to determine the accuracy of a smartphone application (APP) for assessing vertical jump performance in elite female volleyball athletes. 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. Following a dynamic warm-up protocol, each participant performed two CMJ familiarization attempts, followed by three recorded attempts that were simultaneously measured by an APP and a force plate system (FPS), with 1-minute rest periods between trials. A smartphone fixed to a tripod approximately 1.0 m in front of the participant was used to record the CMJ using the APP. Two Certified Strength and Conditioning Specialists observed each CMJ performance to verify proper technique. 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 35.3 ± 3.8 cm for the APP and 36.2 ± 3.9 cm for the FPS, which was significantly different (p < 0.001). The CMJ values from the two devices showed a significant correlation (r = 0.99, p < 0.001). Additionally, the APP had a standard error of estimate (SEE) of ±0.27 cm, while limits of agreement (LOA) analysis showed a 95% confidence interval (constant error ± 1.96 SD) of -0.84 ± 0.57 cm. Conclusions: The APP and FPS provided slightly different mean CMJ values. However, when compared to the criterion FPS, the APP displayed a strong correlation, and small SEE and LOA values. Therefore, it appears that the APP provides a valid assessment of CMJ in elite female volleyball players. Practical Applications: Practitioners who work with elite female volleyball players should consider using a CMJ testing APP when an FPS is unavailable. Acknowledgements: N/A