Comparison of Two Methods to Measure Clean and Push Press Bar Velocity

Document Type

Article

Publication Date

2015

Publication Title

Journal of Strength and Conditioning Research Supplement

DOI

10.1519/JSC.0000000000001238

ISSN

1533-4287

Abstract

While bar displacement has traditionally been measured using camera-based methods, several portable systems using cords connecting directly to the bar are now available. These devices, known as Linear Position Transducers (LPT), offer multiple logistics and pragmatic benefits, including ease of use, portability and cost effectiveness when compared to labs equipped with 3D motion capture technology. Because (a) many exercises typically used in conventional strength and conditioning involve the bar moving in multiple planes, (b) bar paths and movement planes may change across load intensity, and (c) bar velocity is critical to successful weightlifting, the validity of using a LPT has practical importance. Purpose: To compare camera and LPT measurement of vertical bar velocity during cleans and push presses. Methods: Healthy men (n = 10) aged 18–30 years completed one test session during which 2 repetitions of the power clean and push press at 50, 60 and 80% of their reported 1 repetition maximum (1RM) were completed. Order of exercises performed was randomized. Simultaneous measurement of bar displacement was made by a 12 camera system (Vicon, Oxford, UK) and a LPT (Tendo Power Analyzing Unit, Tendo Power Machines, Slovak Republic), from which peak vertical velocities were computed. Correlational analyses were conducted between the 2 methods. Additionally separate method by load analysis of variance were conducted. Results: Moderate strength relationships were demonstrated between the 2 methods for both the clean (50% r = 0.96, 60% r = 0.95, 80% r = 0.80) and push press (50% r = 0.98, 60% r = 0.75, 80% r = 0.83). While the camera peak velocities were always significantly higher p (p > 0.05) for both the clean and push press at 50% (Clean: 95% CIdiff = 0.155 to 0.296 m·s−1, Push Press: 95% CIdiff = 0.079 to 0.194 m·s−1), 60% (Clean: 95% CIdiff = 0.078 to 0.215 m·s−1, Push Press: 95% CIdiff = −0.008 to 0.507 m·s−1), and 80% (Clean: 95% CIdiff = 0.024 to 0.230 m·s−1, Push Press: 95% CIdiff = −0.001 to 0.316 m·s−1) across the 3 loads for both the clean (50%) and push press. Conclusions: Given the strong association between these measurement techniques, this work suggests a portable LPT system may be efficacious for use in non-laboratory settings. However, the statistically significant difference between the 2 methods, with the cameras consistently measuring higher bar velocities, indicates that strength and conditioning professionals should realize the LPT velocities underestimate of the true bar velocity. Since this study engaged intermediate lifters, it would be of interest to investigate whether these results are seen with lifters of higher proficiency, particularly if curvature of bar trajectory affects the absolute and/or relative values of these methods. Practical Applications: Effective and accurate assessment protocols are paramount to the achievement of optimal athletic performance. With the advancement of technology and the 1 repetition maximum no longer sufficing as a comprehensive evaluation of physical performance, strength and conditioning professionals may consider the use of a LPT which are an accurate measurement tool for the assessment of bar velocity that gives them more flexibility in location.

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Copyright © 2016 by the National Strength & Conditioning Association

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