Comparing Repetition-Velocity Output from a Motor-Integrated Magnetic Sensing System with That of a Linear Position Transducer Across Resistance Exercises and Loads: A Human Trial Experiment

Equipment with integrated sensing can now provide repetition-velocity feedback without external sensors. However, whether their output agrees with that of established commercial linear position transducers has yet to be investigated. This study addresses this gap by comparing repetition-velocity measurements obtained from the motor-integrated magnetic sensing system of MOTY V with those obtained from GymAware RS to evaluate inter-device agreement and measurement characteristics. Deadlifts and squats were performed at 40%, 60%, and 80% of estimated one-repetition maximum by 15 male students, with both devices simultaneously measuring bar movement. The final analysis included 897 paired repetitions out of 900 planned pairs. Mean velocities were 0.7102 ± 0.1496 m/s for MOTY V and 0.6816 ± 0.1410 m/s for GymAware RS. The mixed-effects mean bias (MOTY V–GymAware RS) was 0.0285 m/s (95% confidence interval [CI], 0.0216–0.0353), with repeated-measures 95% limits of agreement ranging from −0.0773 to +0.1342 m/s. Mean absolute error and root mean square error were 0.0467 and 0.0609 m/s, respectively. Repetition-level correlation was r = 0.933, and set-level absolute-agreement intraclass correlation coefficient (ICC) was 0.958 (95% CI, 0.929–0.973). Mean bias did not differ significantly by exercise, load, or their interaction, whereas proportional bias was significant (β = 0.125, p < 0.001). MOTY V showed high agreement with GymAware RS, but small positive systematic and proportional biases preclude assuming direct interchangeability.