Wang Yizhang, Wang Xintang, Luan Chenglin, Shan Wei, Gong Lijing
China Institute of Sport and Health Science, Beijing Sport University, Beijing, China.
Key Laboratory of Exercise and Physical Fitness, Ministry of Education, Beijing Sport University, Beijing, China.
Front Sports Act Living. 2024 May 30;6:1405118. doi: 10.3389/fspor.2024.1405118. eCollection 2024.
Vertical stiffness (K) can be used to evaluate sports performance and injury risk in players. The My Jump 2 smartphone application (App), is increasingly being used by researchers, coaches, and players in the competitive sports field. We aimed to analyze the reliability and concurrent validity of the My Jump 2 app for measuring K in male college players.
Twenty male college players (10 soccer players, 10 basketball players; age, 20.2 ± 1.3 years old; weight, 76.4 ± 6.0 kg; height, 178.3 ± 4.7 cm) volunteered to take part in this study. Three drop jumps were performed by participants from 30 cm to 40 cm on a force platform and retested after three days. All the jumps were recorded by both the Force platform and the My Jump 2 app. Data obtained from the above two devices were compared using the paired tests, intraclass correlation coefficient (ICC), coefficient of variation (CV), Pearson product moment correlation coefficient (), Bland-Altman plots, and one-way regression.
There was almost perfect agreement between measurement instruments for the K value (ICC > 0.972, 95% CI = 0.954-0.992, < 0.01). Almost perfect agreement was observed between evaluators (ICC > 0.989, 95% CI = 0.981-0.997, < 0.05). Also, the My Jump 2 app showed excellent intra-rater reliability in all participants (ICC = 1.000, 95% CI = 1.000-1.000, < 0.001). The My Jump 2 showed good variability when measuring K at T1 30 cm (CV = 5.4%), T1 40 cm (CV = 6.7%), T2 30 cm (CV = 5.0%), and T2 40 cm (CV = 10.3%). The test-retest reliability of My Jump 2 was moderate to good at 30 cm (ICC = 0.708, 95% CI = 0.509-0.827); however, it was lower to moderate at 40 cm (ICC = 0.445, 95% CI = 0.222-0.625). Very large correlations were observed between the force platform and the My Jump 2 for K ( > 0.9655, < 0.001).
The My Jump 2 smartphone application showed excellent reliability and intra-rater consistency in measuring K in male college players. While demonstrating excellent intra-rater consistency and strong agreement with force platform measurements, it showed slightly lower reliability at higher jump heights. Overall, the My Jump 2 app is a valid tool for evaluating K in college players with careful consideration of its limitations, particularly at higher jump heights.
垂直刚度（K）可用于评估运动员的运动表现和受伤风险。My Jump 2智能手机应用程序（App）在竞技体育领域越来越受到研究人员、教练和运动员的使用。我们旨在分析My Jump 2应用程序在测量男性大学生运动员K值方面的可靠性和同时效度。
20名男性大学生运动员（10名足球运动员，10名篮球运动员；年龄，20.2±1.3岁；体重，76.4±6.0 kg；身高，178.3±4.7 cm）自愿参加本研究。参与者在测力平台上从30 cm到40 cm进行三次下蹲跳，并在三天后重新测试。所有跳跃均由测力平台和My Jump 2应用程序记录。使用配对t检验、组内相关系数（ICC）、变异系数（CV）、皮尔逊积矩相关系数（）、布兰德-奥特曼图和一元回归对从上述两种设备获得的数据进行比较。
测量仪器之间对于K值几乎完全一致（ICC>0.972，95%CI=0.954 - 0.992，<0.01）。评估者之间观察到几乎完全一致（ICC>0.989，95%CI=0.981 - 0.997，<0.05）。此外，My Jump 2应用程序在所有参与者中显示出极好的评估者内可靠性（ICC = 1.000，95%CI = 1.000 - 1.000，<0.001）。My Jump 2在测量T1 30 cm（CV = 5.4%）、T1 40 cm（CV = 6.7%）、T2 30 cm（CV = 5.0%）和T2 40 cm（CV = 10.3%）的K值时显示出良好的变异性。My Jump 2在30 cm处的重测可靠性为中等至良好（ICC = 0.708，95%CI = 0.509 - 0.827）；然而，在40 cm处则为低至中等（ICC = 0.445，95%CI = 0.222 - 0.625）。测力平台和My Jump 2对于K值观察到非常大的相关性（>0.9655，<0.001）。
My Jump 2智能手机应用程序在测量男性大学生运动员的K值方面显示出极好的可靠性和评估者内一致性。虽然展示了极好的评估者内一致性以及与测力平台测量的高度一致性，但在较高跳跃高度时其可靠性略低。总体而言，My Jump 2应用程序是评估大学生运动员K值的有效工具，但需仔细考虑其局限性，尤其是在较高跳跃高度时。
