Validity and reliability of a novel iPhone app for the measurement of barbell velocity and 1RM on the bench-press exercise

• Published in: Journal of sports sciences 2018-01, Vol.36 (1), p.64-70
• Main Authors: Balsalobre-Fernández, Carlos, Marchante, David, Muñoz-López, Mario, Jiménez, Sergio L.
• Format: Article
• Language: English
• Subjects: Adult; Biomechanical Phenomena; Biomechanics; Humans; Male; Mobile Applications; Muscle Strength - physiology; Observer Variation; Reproducibility of Results; resistance training; Resistance Training - methods; Smartphone; Software; Strength training; Velocity; Weight Lifting - physiology; Weightlifting
• ISSN: 0264-0414; 1466-447X
• DOI: 10.1080/02640414.2017.1280610

The purpose of this study was to analyse the validity and reliability of a novel iPhone app (named: PowerLift) for the measurement of mean velocity on the bench-press exercise. Additionally, the accuracy of the estimation of the 1-Repetition maximum (1RM) using the load-velocity relationship was tested. To do this, 10 powerlifters (Mean (SD): age = 26.5 ± 6.5 years; bench press 1RM · kg −1  = 1.34 ± 0.25) completed an incremental test on the bench-press exercise with 5 different loads (75-100% 1RM), while the mean velocity of the barbell was registered using a linear transducer (LT) and Powerlift. Results showed a very high correlation between the LT and the app (r = 0.94, SEE = 0.028 m · s −1 ) for the measurement of mean velocity. Bland-Altman plots (R 2  = 0.011) and intraclass correlation coefficient (ICC = 0.965) revealed a very high agreement between both devices. A systematic bias by which the app registered slightly higher values than the LT (P