Reliability of technologies to measure the barbell velocity: Implications for monitoring resistance training

Abstract

This study investigated the inter-and intra-device agreement of four new devices marketed for barbell velocity measurement. Mean, mean propulsive and peak velocity outcomes were obtained for bench press and full squat exercises along the whole load-velocity spectrum (from light to heavy loads). Measurements were simultaneously registered by two linear velocity transducers T-Force, two linear position transducers Speed4Lifts, two smartphone video-based systems My Lift, and one 3D motion analysis system STT. Calculations included infraclass correlation coefficient (ICC), Bland-Altman Limits of Agreement (LoA), standard error of measurement (SEM), smallest detectable change (SDC) and maximum errors (MaxError). Results were reported in absolute (m/s) and relative terms (%1RM). Three velocity segments were differentiated according to the velocity-load relationships for each exercise: heavy (� 80% 1RM), medium (50% < 1RM < 80%) and light loads (� 50% 1RM). Criteria for acceptable reliability were ICC > 0.990 and SDC < 0.07 m/s (~5% 1RM). The T-Force device shown the best intra-device agreement (SDC = 0.01-0.02 m/s, LoA <0.01m/s, MaxError = 1.3-2.2%1RM). The Speed4Lifts and STT were found as highly reliable, especially against lifting velocities �1.0 m/s (Speed4Lifts, SDC = 0.01-0.05 m/s; STT, SDC = 0.02-0.04 m/s), whereas the My Lift app showed the worst results with errors well above the acceptable levels (SDC = 0.26-0.34 m/s, MaxError = 18.9-24.8%1RM). T-Force stands as the preferable option to assess barbell velocity and to identify technical errors of measurement for emerging monitoring technologies. Both the Speed4Lifts and STT are fine alternatives to T-Force for measuring velocity against high-medium loads (velocities � 1.0 m/s), while the excessive errors of the newly updated My Lift app advise against the use of this tool for velocity-based resistance training.

The Validity and Reliability of Commercially Available Resistance Training Monitoring Devices: A Systematic Review

“…In stating this, future research must consider utilising a broader range of exercises (e.g., Olympic weightlifting exercises and their derivatives) and loads to be confident of the reliability and validity of devices. For the assessment of reliability, only three studies have assessed the agreement between two different devices of the same brand (i.e., inter-device) [22,36,51]. In contrast, there has been a substantial amount of research concerning intra-device reliability [28,48,52]; however, it must be noted that all but one of these studies [22] failed to differentiate technological variation from biological variation to establish their respective influence on the unit's reliability.…”

“…Finally, with the increasing interest in monitoring resistance training performance, mobile phone apps have also become available [10,24,36,69,70]. While there is conflicting evidence [24,36,51,70], it appears that substantial bias and error can be introduced when different devices and/or users implement these measuring tools [23]. Thus, practitioners should ensure thorough familiarisation and standardised protocols when using these applications.…”

Validity and Reliability of Mobile Applications for Assessing Strength, Power, Velocity, and Change-of-Direction: A Systematic Review

“…Characteristics of the included studies can be found in Table 3 . The apps presented in the included articles were compared with motion a capture system [ 40 , 61 , 68 , 69 ], linear encoder and transducers [ 56 , 59 , 60 , 62 , 63 , 64 , 71 ], as well as with contact platforms [ 37 , 39 , 41 , 57 , 61 , 62 , 63 , 66 ], accelerometers [ 59 , 62 , 63 , 68 , 70 ], and time photocells [ 55 , 65 , 67 , 70 ].…”

“…Among the included studies, [ 39 , 53 , 56 , 59 , 62 , 63 , 64 ] tested the bench press, [ 64 , 68 ] the back squat, [ 60 ] the half squat and full squat [ 39 , 53 ], [ 40 ] the snatch, [ 53 ] the hip thrust, [ 68 ] the power clean, [ 37 , 41 , 57 , 61 , 66 , 71 ] the vertical jump (CMJ, SJ or DJ), [ 58 ] the running, [ 65 , 67 ] the sprint or agility [ 55 , 70 ] the static and dynamic arm swing.…”

“…As mentioned, typical outcomes related to strength and power, velocity, and change-of-direction actions have focused on the velocity, time, or the displacement of a movement [ 36 ]. These main outcomes are, in a sense, able to take measurements using image-based or video-based analyses incorporated into smartphone cameras [ 37 , 38 , 39 ]. Though they are not automatic, a wide range of apps have simple and user-friendly processes for collecting and treating data.…”