AUTHOR=Balsalobre-Fernández Carlos , Marchante David , Baz-Valle Eneko , Alonso-Molero Iván , Jiménez Sergio L. , Muñóz-López Mario 

TITLE=Analysis of Wearable and Smartphone-Based Technologies for the Measurement of Barbell Velocity in Different Resistance Training Exercises

JOURNAL=Frontiers in Physiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2017.00649

DOI=10.3389/fphys.2017.00649

ISSN=1664-042X

ABSTRACT=<p>The purpose of this study was to analyze the validity, reliability, and accuracy of new wearable and smartphone-based technology for the measurement of barbell velocity in resistance training exercises. To do this, 10 highly trained powerlifters (age = 26.1 ± 3.9 years) performed 11 repetitions with loads ranging 50–100% of the 1-Repetition maximum in the bench-press, full-squat, and hip-thrust exercises while barbell velocity was simultaneously measured using a linear transducer (LT), two <italic>Beast</italic> wearable devices (one placed on the subjects' wrist –BW–, and the other one directly attached to the barbell –BB–) and the iOS <italic>PowerLift</italic> app. Results showed a high correlation between the LT and BW (<italic>r</italic> = 0.94–0.98, SEE = 0.04–0.07 m•s<sup>−1</sup>), BB (<italic>r</italic> = 0.97–0.98, SEE = 0.04–0.05 m•s<sup>−1</sup>), and the <italic>PowerLift</italic> app (<italic>r</italic> = 0.97–0.98, SEE = 0.03–0.05 m•s<sup>−1</sup>) for the measurement of barbell velocity in the three exercises. Paired samples <italic>T</italic>-test revealed systematic biases between the LT and BW, BB and the app in the hip-thrust, between the LT and BW in the full-squat and between the LT and BB in the bench-press exercise (<italic>p</italic> &lt; 0.001). Moreover, the analysis of the linear regression on the Bland-Altman plots showed that the differences between the LT and BW (<italic>R</italic><sup>2</sup> = 0.004–0.03), BB (<italic>R</italic><sup>2</sup> = 0.007–0.01), and the app (<italic>R</italic><sup>2</sup> = 0.001–0.03) were similar across the whole range of velocities analyzed. Finally, the reliability of the BW (ICC = 0.910–0.988), BB (ICC = 0.922–0.990), and the app (ICC = 0.928–0.989) for the measurement of the two repetitions performed with each load were almost the same than that observed with the LT (ICC = 0.937–0.990). Both the <italic>Beast</italic> wearable device and the <italic>PowerLift</italic> app were highly valid, reliable, and accurate for the measurement of barbell velocity in the bench-press, full-squat, and hip-thrust exercises. These results could have potential practical applications for strength and conditioning coaches who wish to measure barbell velocity during resistance training.</p>