Measurement of barbell velocity is a simple and effective way to control strength training. To assess the concurrent validity of different technological approaches measuring barbell velocity, video-analysis (Kinovea), linear velocity transducer (Speedograph), and an inertial measurement unit (VmaxPro) were compared. Sixty-eight female and male sport science students lifted two repetitions in the bench press exercise at self-selected barbell loads. Peak vertical barbell velocity (Vmax) was parallel measured during the concentric phase of the lift using the aforementioned devices. Concordance correlation coefficient (CCC), Deming regression (DR) and Bland-Altman analysis (BA) were used to assess relative and absolute concurrent validity of Vmax measured with Kinovea, Speedograph, and VmaxPro. Results confirmed high concurrent validity of Speedograph and VmaxPro (CCC = 0.99, standard deviation of differences [SDD] = 0.04 m·s-1) without detecting proportional or constant bias. In contrast, Vmax measured with Kinovea showed poor concurrent validity to Speedograph (CCC = 0.83) and VmaxPro (CCC = 0.81) with significant proportional and constant bias. Regression based re-calibration of Vmax from Kinovea resulted in an SDD = 0.09 m·s-1 compared to Speedograph and an SDD = 0.08 m·s-1 compared to VmaxPro. Among the three tested devices, Vmax assessed using Kinovea showed poor concurrent validity. Furthermore, as Kinovea showed proportional bias compared to Speedograph and VmaxPro, application-specific re-calibration of Kinovea should be applied when barbell velocity data is compared to Speedograph and VmaxPro.
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