Validity and Reliability of My Jump 2 App for Jump Performance in Judo Players

Background: The height of the jump is an essential factor in judo because through this parameter, coaches can assess the power of the lower limbs, which is essential in the performance of judo techniques. The My Jump 2 (MJ2) application is a validated application to calculate the jump height, however, to the best of our knowledge, no study has tested this smartphone application in judokas. Objective: The objective of this study is to analyse the validity and reliability of the app MJ2 for measuring jump height in judokas. Methods: Twenty-one judokas were recruited, who performed 2 countermovement jumps on the Chronojump platform (42 jumps). Simultaneously, the videos of the jumps were captured using recommendations in the app and were later processed and analyzed independently by two evaluators. Results: The data revealed a good correlation for the calculated jump height with both tools used. In the Bland-Altman analysis, it was observed that the differences between instruments and the inter-evaluator differences were quite low. According to the Pearson correlation (MJ2 vs CJ), the value was r=0.97. As for the height of the jump measured using the MJ2 app, an average of 26.38 ± 8.89 cm and 26.25 ± 8.14 was obtained for each evaluator, while the average for the Chronojump platform was 26.69 ± 8.14. Conclusion: The concordant data and correlation found indicate that MJ2 application can be used as a method to estimate jump height in judokas.