Reliability and Validity of Mobile Device Apps for Measuring Barbell Velocity During the Bench Press

The objective of this research was to analyse the validity and reliability of mobile device apps used to measure mean velocity in the bench press exercise. 15 men completed bench press tests with 50% of their 1-repetition maximum, with mean velocity being recorded by a linear transducer (LT) and 3 mobile device apps: a mobile app based on computer vision (Metric VBT, MV), an app based on an inertial measurement unit within a mobile phone (Tempro, TP), and an app based on an inertial measurement unit inside a smartwatch (Spleeft, SF). The findings indicate the reliability hierarchy of the devices, from highest to lowest, as follows: Metric VBT (ICC = 0.935); Tempro (ICC = 0.702); and Spleeft (ICC = 0.713). The correlation between linear sensors (LT) and Metric VBT was practically perfect (r=0.937, p<0.001), whereas the app correlation based on inertial sensors within mobile devices was lower (TP: r=0.751, p<0.001; SF: r=0.733,p<0.001). These results suggest that this Metric VBT has higher validity and reliability than Tempro and Spleeft.