Use of concentric linear velocity to monitor flywheel exercise load

Abstract

Purpose: To propose the concentric linear velocity measurement as a valid method to quantify load and individualise the prescription of flywheel training, we investigated the relationship between inertial load and mean concentric linear velocity (MCLV) during the flywheel squat exercise in a wide spectrum of intensities. In addition, we compared MCLV and subjective rating of perceived exertion (RPE) after each load.Methods: Twenty-five physically active men volunteered for this study (26.5 ± 2.9 years, 179.5 ± 4.2 cm, 81.6 ± 8.6 kg). After familiarization, all participants performed two inertial progressive load tests on separated days to determine the flywheel load-velocity profile and its reliability. Each participant performed 5 set of 6 repetitions of the flywheel squat exercise with different inertial loads (0.047, 0.104, 0.161, 0.245, 0.321 kg m2) selected in a counterbalanced and randomized order for each testing day. Average MCLV and RPE for each load were compared.Results: The inter-session intraclass correlation coefficient (ICC) showed values above 0.9 in all the included outcomes (MCLV: ICC = 0.91; RPE: ICC = 0.93). A significant correlation (p < 0.01, R2 = 0.80) between inertial load and MCLV was found. Similarly, significant correlation models (p < 0.01) were observed between RPE and load (R2 = 0.87) and (R2 = 0.71) between RPE and MCLV.Conclusion: The control of MCLV during flywheel exercise can be proposed as a valid method to quantify load and to individualize the prescription of flywheel training. In addition, RPE responses have demonstrated significant correlations with load and velocity. Therefore, RPE has been proposed as a valid and reliable alternative to control flywheel training.

Effects of Relative Inertial Load on Quadriceps Electromyography during Maximal Effort Flywheel-based Iso-Inertial Training (FIT) Squats

“…However, those with greater strength will likely move at a faster velocity for any given moment of inertia than those with lower strength. Due to the inverse relationship between maximal movement velocity and inertial load, it has recently been proposed that the velocityinertia relationship may be a more appropriate means of quantifying FIT exercise intensity than absolute moment of inertia [6][7][8][9][10] . Here, we used relative inertial load (%1RM•m 2 ) to quantify relative intensity.…”

“…Quantifying intensity during FIT has been problematic in previous studies 6,7 . Due to the inertial nature of FIT, exercise can be successfully completed as long as force is greater than zero since any non-zero force will be sufficient to rotate the flywheel 7 .…”

Validity and Reliability of Inertial Measurement System for Linear Movement Velocity in Flywheel Squat Exercise

“…The foundation of VBT centers on the quantification of concentric linear velocity of each repetition (e.g., concentric mean velocity or mean propulsive velocity) with a linear position transducer [ 1 ], smartphone app [ 6 ], inertial movement sensor [ 7 ] or wearable devices [ 8 ]. In addition to the quantification of velocity, these devices can allow for the estimation of other kinetic and kinematic variables such as force and power [ 4 ].…”

“…Rotary encoders are usually attached to the main axis of rotation, providing information about wheel angular velocity that can be used to estimate force and power when considering the moment of inertia [ 25 ]. However, the use of rotary encoders comes with some challenges as the inertia flywheel only changes its rotational direction between repetitions, which makes it difficult to differentiate between concentric and eccentric muscle actions and may smooth the oscillations of high-frequency velocity actions [ 7 , 26 ]. This may result in the linear encoder providing inaccurate kinetic and kinematic data [ 22 , 24 ].…”

“…To overcome these issues, recent studies have proposed the use of linear velocity to monitor concentric and eccentric velocity during flywheel exercises [ 7 , 22 , 26 ]. To this end, some studies have used an Inertial Measurement System (IMS) sensor (IonClinics & Deionic S.L, L’Alcudia, Spain) to control flywheel velocity [ 27 , 28 ].…”