The Validity and Reliability of the My Jump 2 App for Measuring the Reactive Strength Index and Drop Jump Performance

T Haynes, C Bishop, M Antrobus, Jon Brazier

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)
40 Downloads (Pure)

Abstract

BACKGROUND: This is the first study to independently assess the concurrent validity and reliability of the My Jump 2 app for measuring drop jump performance. It is also the first to evaluate the app's ability to measure the reactive strength index (RSI).

METHODS: Fourteen male sport science students (age: 29.5±9.9 years) performed three drop jumps from 20 cm and 40 cm (totaling 84 jumps), assessed via a force platform and the My Jump 2 app. Reported metrics included reactive strength index, jump height, ground contact time, and mean power. Measurements from both devices were compared using the intraclass correlation coefficient (ICC), Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation (CV) and Bland-Altman plots.

RESULTS: Near perfect agreement was seen between devices at 20 cm for RSI (ICC=0.95) and contact time (ICC=0.99) and at 40 cm for RSI (ICC=0.98), jump height (ICC=0.96) and contact time (ICC=0.92); with very strong agreement seen at 20 cm for jump height (ICC=0.80). In comparison with the force plate the app showed good validity for RSI (20 cm: r=0.94; 40 cm; r=0.97), jump height (20 cm: r=0.80; 40 cm; r=0.96) and contact time (20 cm=0.96; 40 cm; r=0.98).

CONCLUSIONS: The results of the present study show that the My Jump 2 app is a valid and reliable tool for assessing drop jump performance.

Original languageEnglish
Pages (from-to)253-258
Number of pages6
Journal The Jounral of Sports Medicine and Physical Fitness
Volume59
Issue number2
Early online date27 Mar 2018
DOIs
Publication statusPublished - 1 Feb 2019

Keywords

  • physical performance
  • drop jumps
  • Plyometrics
  • testing

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