Different Accuracy of Commercial Devices for Monitoring Movement Velocity During Resistance Training

This study aimed to evaluate the accuracy of four commercial devices in monitoring movement velocity across different loads and tracking velocity fluctuations within a given set. Twenty well-trained male participants completed a free weight squat testing session consisting of an incremental loading test from self-reported 20% 1RM to 90% 1RM, followed by a set of five squats at 70% 1RM. Movement mean velocity was recorded using two linear position transducers (GymAware and Vitruve) and two inertial measurement units (Enode and Output). The Qualisys system was set as the reference. Among the tested devices, only GymAware and Enode did not exhibit systematic bias or heteroscedasticity errors across all loads compared to the Qualisys system (p ≥ .165). GymAware (error ≤6.01%) and Enode (error ≤4.43%) revealed the smallest absolute percentage difference compared to the Qualisys system. When assessing barbell velocity fluctuations within a set, Output showed weaker Spearman correlations with the Qualisys system compared to other devices (r = 0.531), while the other three devices revealed very large correlations with the Qualisys system (r ≥ 0.744). Based on these findings, GymAware and Enode were the most accurate choices during free weight squats.