Validity and reliability of the My Lift app in determining 1RM for deadlift and back squat exercises

Abstract

Smartphone technologies are seen as a rapidly developing field of research in physical activity research. However, it is important to use smartphone applications that have proven validity and reliability in performance measurement. This study aimed to determine the validity and reliability of the My Lift mobile app used for the determining estimated 1RM for conventional deadlift and barbell back squat exercises. 10 male weightlifters (X-age: 17.50 +/- 1.27 years) voluntarily participated in the study. For the conventional deadlift and barbell back squat movements of the weightlifters, My Lift app measurements were obtained during the 1RM test simultaneously with sub-maximal loads (75-85% 1RM). Results obtained from My Lift app and actual 1RM were compared with Bland-Altman plots. The My Lift app provided high reliability interclass correlation coefficient for conventional deadlift and barbell back squat (ICC = 0.99). The results were highly correlated obtained from My Lift app and the actual 1RM test (determination coefficient for conventional deadlift: R-2 = 0.99; barbell back squat: R-2 = 0.99). When compared with the actual 1RM test, My Lift app that used to determine estimated 1RM is a very valid and reliable tool. The My Lift app can be used by athletes and coaches as a practical and valid measurement tool for determining 1RM using sub-maximal loads.