Exercise & Training

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.

Kim A • Sensors (Basel, Switzerland) • 2026

PubMed 42944328 DOI 10.3390/s26206466

TL;DR

MOTY V showed high agreement with GymAware RS, but small positive systematic and proportional biases preclude assuming direct interchangeability.

Key Findings

Results

The motor-integrated MOTY V system gave slightly higher mean repetition velocities than the GymAware RS linear position transducer.

Mean velocities were 0.7102 ± 0.1496 m/s for MOTY V and 0.6816 ± 0.1410 m/s for GymAware RS.
The final analysis included 897 paired repetitions out of 900 planned pairs.
Fifteen male students performed deadlifts and squats at 40%, 60%, and 80% of estimated one-repetition maximum, with both devices measuring bar movement simultaneously.

Results

There was a small but statistically significant positive systematic bias of MOTY V relative to GymAware RS.

The mixed-effects mean bias (MOTY V - GymAware RS) was 0.0285 m/s (95% CI, 0.0216-0.0353).
Repeated-measures 95% limits of agreement ranged from -0.0773 to +0.1342 m/s.

Results

Error magnitudes between devices were modest.

Mean absolute error was 0.0467 m/s.
Root mean square error was 0.0609 m/s.

Results

The two devices showed strong correlation and excellent absolute agreement.

Repetition-level correlation was r = 0.933.
Set-level absolute-agreement intraclass correlation coefficient was 0.958 (95% CI, 0.929-0.973).

Results

Mean bias did not differ significantly by exercise, load, or their interaction.

Tested across deadlift and squat at 40%, 60%, and 80% of estimated 1RM.
The bias was therefore consistent across the exercise and load conditions tested.

Results

A significant proportional bias was present, meaning the difference between devices changed with velocity magnitude.

Proportional bias had β = 0.125, p < 0.001.
Together with the positive systematic bias, this led the author to conclude the devices should not be assumed directly interchangeable.

What This Means

This study compared two ways of measuring how fast a barbell moves during lifting. One was MOTY V, a training machine with a motor and built-in magnetic sensor. The other was GymAware RS, a widely used external sensor that tracks bar position. Fifteen male students did deadlifts and squats at light, moderate, and heavy loads (40%, 60%, 80% of estimated max) while both devices recorded the same repetitions, giving 897 usable paired repetitions. The two devices agreed closely overall (correlation of 0.93 for repetitions and 0.96 for sets). However, MOTY V read slightly faster on average, by about 0.03 m/s, and the gap changed somewhat with the speed of the lift. This difference was similar across both exercises and all three loads. The range of repetition-to-repetition differences was fairly wide, from about -0.08 to +0.13 m/s. This research suggests that equipment with built-in sensing can give useful velocity feedback without extra devices. But because of the small consistent differences, numbers from MOTY V may not be directly swappable with GymAware RS numbers, for example when comparing data across devices. The study involved only young men and two exercises, so results may not apply to other groups or lifts.

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Citation

Kim A. (2026). 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.. Sensors (Basel, Switzerland). https://doi.org/10.3390/s26206466

Key Findings

What This Means

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