Concurrent Validity of Field-Based Diagnostic Technology Monitoring Movement Velocity in Powerlifting Exercises

Abstract

Mitter, B, Hölbling, D, Bauer, P, Stöckl, M, Baca, A, and Tschan, H. Concurrent validity of field-based diagnostic technology monitoring movement velocity in powerlifting exercises. J Strength Cond Res 35(8): 2170–2178, 2021—The study was designed to investigate the validity of different technologies used to determine movement velocity in resistance training. Twenty-four experienced powerlifters (18 male and 6 female; age, 25.1 ± 5.1 years) completed a progressive loading test in the squat, bench press, and conventional deadlift until reaching their 1 repetition maximum. Peak and mean velocity were simultaneously recorded with 4 field-based systems: GymAware (GA), FitroDyne (FD), PUSH (PU), and Beast Sensor (BS). 3D motion capturing was used to calculate specific gold standard trajectory references for each device. GA provided the most accurate output across exercises (r = 0.99–1, ES = −0.05 to 0.1). FD showed similar results for peak velocity (r = 1, standardized mean bias [ES] = −0.1 to −0.02) but considerably less validity for mean velocity (r = 0.92–0.95, ES = −0.57 to −0.29). Reasonably valid to highly valid output was provided by PU in all exercises (r = 0.91–0.97, ES = −0.5 to 0.28) and by BS in the bench press and for mean velocity in the squat (r = 0.87–0.96, ES = −0.5 to −0.06). However, BS did not reach the thresholds for reasonable validity in the deadlift and for peak velocity in the squat, mostly due to high standardized mean bias (ES = −0.78 to −0.63). In conclusion, different technologies should not be used interchangeably. Practitioners who require negligible measurement error in their assessment of movement velocity are advised to use linear position transducers over inertial sensors.

Validity of an inertial system for measuring velocity, force, and power during hamstring exercises performed on a flywheel resistance training device

“…However, since the inertial load is not constant, it is difficult to quantify essential variables for training. While the velocity of movement can be measured using various technologies (e.g., linear encoders, optical motion sensing system, or smartphone applications) ( Mitter et al, 2019 ; Pérez-Castilla et al, 2019 ), the estimation of force and power are conditioned, since inertia from the concentric action directly affects force in the eccentric action ( Weakley et al, 2019 ). Thus, force and power are commonly measured by combining several sensors (e.g., force gauges and linear encoders), calculating power as the product of force and velocity ( Tous-Fajardo et al, 2006 ; Martinez-Aranda & Fernandez-Gonzalo, 2017 ).…”

The reliability of a linear position transducer and commercially available accelerometer to measure punching velocity in junior boxing athletes

“…A commercially available, inexpensive and user-friendly inertial measurement device is the accelerometer, which has recently gained popularity for measuring a variety of linear and angular spatio-temporal dynamics across weightlifting, kicking, cycling and throwing sports. 8 However, several accelerometers have demonstrated a poor ability to accurately measure linear kinematics during various tasks including powerlifting, 9 resistance exercises (e.g., bench press, squat and deadlift) 10 and athletic movements (e.g., vertical jump) 11 when compared with linear position transducers (LPTs). Therefore, a more plausible means for measuring linear kinematic data might be via LPTs, which use a tethered cord to measure two variables; displacement and time.…”

Validation of Inertial Sensor to Measure Barbell Kinematics across a Spectrum of Loading Conditions

“…However, the effect size difference between the IMU and the laboratory measurement values was notably larger at higher intensities compared to the findings of the current investigation, which could be in part due to increased sensitivity of the equipment used in the laboratory comparison method [ 22 ]. Mitter and colleagues [ 13 ] were able to demonstrate reasonable agreement between 3DMOCAP and an IMU device at a more similar sampling rate of 200 Hz. However, the authors did acknowledge that movement cadence (e.g., the inclusion of an isometric pause between the ECC and CON phases) influenced the IMU device accuracy.…”

“…However, the authors did acknowledge that movement cadence (e.g., the inclusion of an isometric pause between the ECC and CON phases) influenced the IMU device accuracy. It is also worth noting that the previous studies [ 13 , 22 ] discussed IMU devices that were mounted on the subject’s forearm, whereas the current investigation used an IMU mounted on the barbell [ 13 , 22 ].…”

“…Linear position transducers have been the long-standing practical preference due to high inter-device agreement with video analysis [ 10 , 11 , 12 ] and relative ease of use. Caution has been advised when considering LPT as a criterion measure due to limitations including the ability to match segment references including trajectories [ 13 ]. The inability to match segment references likely degrades inter-device agreement, which does not necessarily represent device superiority.…”