AGREEMENT OF MY JUMP 2 APP LATERAL VIDEOS FOR ASSESSING JUMP PERFORMANCE: A COMPARISON WITH OPTOJUMP INSTRUMENT

Purpose: The My Jump 2 (MJ2) application is a validated tool used to assess jump performance via frontal slow-motion video analysis. However, no studies have validated the use of lateral video analysis for evaluating jump tests. This perspective offers a detailed view of the vertical movement of the jump, allowing for the evaluation of height, takeoff technique, and landing. This is critically important in the biomechanical analysis of jumps, as it helps identify technical errors and injury risks. Therefore, this study aims to assess the agreement of lateral (right and left) video captured by the MJ2 app for measuring jump performance during the countermovement jump (CMJ), in comparison to measurements obtained using the validated OptoJump (OJ) photoelectric cell system. Methods: Fourteen young soccer players (age: 15 ± 0.3 years; mass: 62 ± 8.9 kg; stature: 170 ± 4.3 cm; leg length: 102 ± 5.3 cm) participated in the study. The CMJs were recorded simultaneously using the OJ system and three iOS devices with the MJ2 app at a frame rate of 240 fps: one device positioned frontally, and two devices positioned laterally to the participant. The week before the tests, the participants were familiarized with the jumping technique. On the day of the tests, each participant performed the jump test three times, following a 10-min warm-up, with a 30- second rest between each jump. Bland–Altman plots and 95% limits of agreement (95% LoA) were used to illustrate and estimate the agreement for the total sample between the OJ system and videos recorded with the MJ2 app for the flight time of the best jump. Results: The analysis showed that all data points, except one, fell within the 95%LoA. Specifically, the mean difference in flight time between measurements obtained from the OJ system and the frontal video was 1.500 ms, with a 95%LoA ranging from - 4.084 ms to 7.084 ms. When comparing with the left lateral video, the mean difference was - 0.571 ms, with a 95%LoA ranging from - 12.720 ms to 11.577 ms. Similarly, with the right video, the mean difference in flight time was - 1.714 ms, with a 95%LoA ranging from - 13.929 ms to 10.500 ms. Conclusions: These results suggest a slight difference between the methods, with OJ generally measuring lower flight times compared to both lateral video analysis and higher flight time related to frontal video. Lateral video analysis using the MJ2 app can enhance training and performance by providing detailed feedback on jump techniques