Criterion validity, and interunit and between-day reliability of the FLEX for measuring barbell velocity during commonly used resistance training exercises
Journal article
Weakley, Jonathon, Chalkley, Daniel, Johnston, Rich, García-Ramos, Amador, Townshend, Andrew, Dorrell, Harry, Pearson, Madison, Morrison, Matthew and Cole, Michael. (2020). Criterion validity, and interunit and between-day reliability of the FLEX for measuring barbell velocity during commonly used resistance training exercises. Journal of Strength and Conditioning Research. 34(6), pp. 1519 - 1524. https://doi.org/10.1519/JSC.0000000000003592
Authors | Weakley, Jonathon, Chalkley, Daniel, Johnston, Rich, García-Ramos, Amador, Townshend, Andrew, Dorrell, Harry, Pearson, Madison, Morrison, Matthew and Cole, Michael |
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Abstract | The aim of this study was to assess the criterion validity, interunit reliability (accounting for technological and biological variance), and between-day reliability of a novel optic laser device (FLEX) for quantifying mean concentric velocity. To assess the validity against a three-dimensional motion capture system and interunit reliability with both technological and biological variation, 18 men and women completed repetitions at 20, 40, 60, 80, 90, and 100% of one repetition maximum in the free-weight barbell back squat and bench press. To assess interunit (technological only) reliability, a purpose-built, calibrated rig completed a set protocol with 2 devices. To assess between-day reliability of the technology, the same protocol was repeated 21 days later. Standardized bias, typical error of the estimate (TEE; %), and Pearson's correlation coefficient (r) were used to assess validity, whereas typical error and coefficient of variation (CV%) were calculated for reliability. Overall, TEE (±90 CL) between the FLEX and criterion measure was 0.03 (±0.004) and 0.04 (±0.005) m·s−1 in the back squat and bench press, respectively. For measures of reliability, overall interunit technological variance (CV% [± 90% confidence interval]) was 3.96% (3.83–4.12) but increased to 9.82% (9.31–10.41) and 9.83% (9.17–10.61) in the back squat and bench press, respectively, when biological variance was introduced. Finally, the overall between-day reliability was 3.77% (3.63–3.91). These findings demonstrate that the FLEX provides valid and reliable mean concentric velocity outputs across a range of velocities. Thus, practitioners can confidently implement this device for the monitoring and prescription of resistance training loads. |
Keywords | back squat; bench press; mean concentric velocity; velocity-based training; measurement |
Year | 2020 |
Journal | Journal of Strength and Conditioning Research |
Journal citation | 34 (6), pp. 1519 - 1524 |
Publisher | Lippincott Williams & Wilkins |
ISSN | 1533-4287 |
Digital Object Identifier (DOI) | https://doi.org/10.1519/JSC.0000000000003592 |
Scopus EID | 2-s2.0-85085538867 |
Page range | 1519 - 1524 |
Research Group | School of Behavioural and Health Sciences |
Publisher's version | File Access Level Controlled |
Place of publication | United States of America |
https://acuresearchbank.acu.edu.au/item/89447/criterion-validity-and-interunit-and-between-day-reliability-of-the-flex-for-measuring-barbell-velocity-during-commonly-used-resistance-training-exercises
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