Reliability and concurrent validity of seven commercially available devices for the assessment of movement velocity at different intensities during the bench press

Abstract

The aim of this study was to compare the reliability and validity of 7 commercially available devices to measure movement velocity during the bench press exercise. Fourteen men completed 2 testing sessions. One-repetition maximum (1RM) in the bench press exercise was determined in the first session. The second testing session consisted of performing 3 repetitions against 5 loads (45, 55, 65, 75, and 85% of 1RM). The mean velocity was simultaneously measured using an optical motion sensing system (Trio-OptiTrack; “gold-standard”) and 7 commercially available devices: 1 linear velocity transducer (T-Force), 2 linear position transducers (Chronojump and Speed4Lift), 1 camera-based optoelectronic system (Velowin), 1 smartphone application (PowerLift), and 2 inertial measurement units (IMUs) (PUSH band and Beast sensor). The devices were ranked from the most to the least reliable as follows: (a) Speed4Lift (coefficient of variation [CV] 5 2.61%); (b) Velowin (CV 5 3.99%), PowerLift (3.97%), Trio-OptiTrack (CV 5 4.04%), T-Force (CV 5 4.35%), and Chronojump (CV 5 4.53%); (c) PUSH band (CV 5 9.34%); and (d) Beast sensor (CV 5 35.0%). A practically perfect association between the Trio-OptiTrack system and the different devices was observed (Pearson’s product-moment correlation coefficient (r) range50.947–0.995; p,0.001) with the only exception of the Beast sensor (r 5 0.765; p , 0.001). These results suggest that linear velocity/position transducers, camerabased optoelectronic systems, and the smartphone application could be used to obtain accurate velocity measurements for restricted linear movements, whereas the IMUs used in this study were less reliable and valid.