Concurrent validity and reliability of real time barbell velocity and power measurement in the squat exercise

Velocity-based training (VBT) has become popular for managing loads during training sessions. Evaluating the validity of these tools is crucial. This study aimed to independently assess the validity and reliability of a smartphone app, My Jump Lab, which provides real-time barbell velocity and power estimations. Fifty sports science students performed two sets of five squats on a Smith machine with a 30-kg load. Barbell velocity measurements were made using a linear position transducer and the app on an iPad mini-6. Concurrent validity was evaluated using Pearson’s correlation coefficient (r) and Bland-Altman plots, while reliability was examined through intraclass correlation coefficient (ICC), coefficient of variation and standard error of measurement. Results showed a high correlation between the instruments for mean concentric velocity (r = 0.860) and mean power (r = 0.844), with Bland-Altman plots indicating minimal bias. The app demonstrated excellent reliability for both variables (ICC > 0.90), with acceptable coefficients of variation for mean concentric velocity (7.62%) and mean power (8.17%). These findings suggest that My Jump Lab is a valid and reliable tool for measuring real-time barbell velocity and power in lower body exercises.