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

Abstract

Background Inertial hamstring exercises promote functional changes leading to lower rates of hamstring injuries. However, variable training measurement systems have not been specifically validated for hamstring exercises. Accordingly, this study aimed to evaluate the validity of the Inertial Measurement System (IMS) to measure the velocity, force, and power during the performance of different hamstring exercises on a flywheel resistance training device. Methods Fifteen males (average age: 22.4 ± 2.5 years; body mass: 77.3 ± 9.8 kg; height: 179.5 ± 7.4 cm; weekly physical activity: 434.0 ± 169.2 min; years of strength training: 4.3 ± 2.2 years) performed the bilateral stiff-leg deadlift (SDL), 45° hip extension (HE), and unilateral straight knee bridge (SKB) in two sessions (familiarization and evaluation) with a 1-week interval between them. The velocity, force, and power (average and peak values) in the concentric and eccentric phases for each of the exercises were recorded simultaneously with IMS and MuscleLab. Results Consistency between IMS and MuscleLab was good to excellent for all variables, with r ranges from 0.824 to 0.966 in SDL, from 0.822 to 0.971 in HE, and from 0.806 to 0.969 in SKB. Acceptable levels of agreement between devices were observed in general for all exercises, the “bias” ranging from 1.1% to 13.2%. Although MuscleLab showed higher values than IMS for peak velocity, force and power values, the effect size was only relevant for 5 of the 36 parameters. IMS is a new and valid system to monitor inertial hamstring exercises on a new flywheel device. In this way, IMS could have potential practical applications for any professional or athlete who wants to monitor inertial hamstring exercises.

Assessment and Evaluation of Force–Velocity Variables in Flywheel Squats: Validity and Reliability of Force Plates, a Linear Encoder Sensor, and a Rotary Encoder Sensor

“…Based on previous research [17], four different inertias were used at different parts of the F-v curve, which fit well with our study purpose while allowing us to compare results from a wide range of velocities in FW squats. The results show excellent inter-set reliability of GRF and v variables, which is in line with the results of previous research [15,34,48]. Moreover, only minor inter-measures reliability differences in GRF and v variables were observed, regardless of the type of variable (mean or peak) and phase of the squat.…”

“…There are many different FW devices on the market, all of which follow the same principle-by accelerating and then consequently braking the mass moment of inertia (I) of the FW. Various systems are used to provide feedback on exercise execution [15] and to track training adaptations using FW devices. However, different FW shaft types and the lack of an objective inertia denominator make it difficult to compare feedback among different software and exercises.…”

“…Strain gauges [15,29], force plates [17,30], rotary [31,32] or linear encoders (including draw wire encoders) [17,29], accelerometers [30], and 3D motion capture [16] were used to measure F and v during FW squats. Recently, using interrupt sensors (encoders and optocouplers) has increased because they are inexpensive, easy to adjust, and portable.…”

Validity and reliability of Veloflex to measure active cervical range of motion in asymptomatic and symptomatic subjects

“…To evaluate the concurrent validity between the measurements of the two devices (VF and CROM), the Pearson’s product-moment correlation coefficient ( r ) was used ( Lin & Yao, 2014 ). Validity is defined as the extent to which the method measures what it is intended to measure ( Martín-San Agustín, Sánchez-Barbadora & García-Vidal, 2020 ). To evaluate the agreement between devices, Bland–Altman plots were created and were calculated: upper and lower limits of agreement (LoA), the mean and the standard deviation of the difference between the two devices (these concepts were called ‘bias’ and ‘imprecision,’ respectively) ( Giavarina, 2015 ), and their respective percentage with respect to the CROM values.…”

Analysis of Compliance with Time under Tension and Force during Strengthening Exercises with Elastic Bands

“…The linear encoder and force gauge information was recorded by the Data Synchronisation Unit (DSU) ML6000 (MuscleLab 4020e, Ergotest Technology AS, Porsgrunn, Norway) [31], which is the unit where the MuscleLab 4020e sensors are connected and integrated. Movement phases and TUTs and force parameters were calculated using customwritten scripts computed with MATLAB (version R2019b; The Mathworks, Natick, MA, USA).…”