Reliability, Validity, and Comparison of Barbell Velocity Measurement Devices during the Jump Shrug and Hang High Pull

Abstract

This study examined the reliability, potential bias, and practical differences between the GymAware Powertool (GA), Tendo Power Analyzer (TENDO), and Push Band 2.0 (PUSH) during the jump shrug (JS) and hang high pull (HHP) performed across a spectrum of loads. Fifteen resistance-trained men performed JS and HHP repetitions with 20, 40, 60, 80, and 100% of their 1RM hang power clean, and mean (MBV) and peak barbell velocity (PBV) were determined by each velocity measurement device. Least-products regression and Bland–Altman plots were used to examine instances of proportional, fixed, and systematic bias between the TENDO and PUSH compared to the GA. Hedge’s g effect sizes were also calculated to determine any meaningful differences between devices. The GA and TENDO displayed excellent reliability and acceptable variability during the JS and HHP while the PUSH showed instances of poor–moderate reliability and unacceptable variability at various loads. While the TENDO and PUSH showed instances of various bias, the TENDO device demonstrated greater validity when compared to the GA. Trivial–small differences were shown between the GA and TENDO during the JS and HHP exercises while trivial–moderate differences existed between GA and PUSH during the JS. However, despite trivial–small effects between the GA and PUSH devices at 20 and 40% 1RM during the HHP, practically meaningful differences existed at 60, 80, and 100%, indicating that the PUSH velocity outputs were not accurate. The TENDO appears to be more reliable and valid than the PUSH when measuring MBV and PBV during the JS and HHP.

Using Barbell Acceleration to Determine the 1 Repetition Maximum of the Jump Shrug

“…The velocity measurement device used in the current study was a linear position transducer that identified the start of the concentric movement based on the lengthening of cable after the initial countermovement. Because the GymAware Powertool accounts for horizontal displacement in its calculations (48), the vertical displacement detected may have been influenced by additional horizontal displacement while using heavier loads. For example, although lighter loads may allow subjects to fully transition back to the mid-thigh position and jump with minimal difficulty, heavier loads may result in a breakdown of technique (33,49).…”

“…A GymAware Powertool (Kinetic Performance Technology, Braddon, Australia) was positioned on the sleeve of the barbell and used to measure vertical barbell displacement, velocity, and acceleration during each JS repetition (48). This placement was used to prevent any disruptions to the subject's grip and the measurement of barbell displacement.…”