The Flywheel Device Shaft Shape Determines Force and Velocity Profiles in the Half Squat Exercise

Abstract

Flywheel resistance training devices can be classified by their shaft shape. The objective of this study was to analyze whether using two flywheel resistance training devices shaft shapes can influence force and velocity production, regardless of the inertia used. Thirty-nine (n = 39) healthy active men participated in this study. They were randomized to perform 3 sets of 7 repetitions at maximal concentric voluntary execution, followed by a break in the last third of the eccentric phase in the half squat exercise. A progressive rotational inertial setting of 0.11, 0.22, and 0.33 kg·m2 was used. Force- and velocity-time profiles were captured using two force plates and a synchronized linear encoder. Statistical parametric mapping was used to compare biomechanical output between the flywheel devices. The level of significance was set at p < 0.05. Force application was significantly higher in the horizontal cylinder-shaped device for the three moments of inertia used in the eccentric phase (p < 0.001). In the concentric phase, force application was significantly higher in the horizontal cylinder-shaped device in 0.11 (p < 0.001) and 0.22 kg·m2 (p < 0.001). The resultant speed was higher in the vertical cone-shaped device in the concentric phase and the eccentric phase for the three moments of inertia (p < 0.001). In conclusion, the flywheel shaft type determines the mechanical output of the half squat exercise, regardless of the moment of inertia used. While a horizontal cylinder-shaped device is more suitable to achieve higher forces, especially in the eccentric phase, a vertical cone-shaped device can be used to achieve higher speeds during the execution of the exercise.

Use of concentric linear velocity to monitor flywheel exercise load

“…This information is also very important, since velocity-based training is a very popular method in strength and conditioning, and it has been recently introduced into flywheel training as well (McErlain-Naylor and Beato, 2020;Maroto-Izquierdo et al, 2021). However, practitioners can struggle to monitor linear velocity in an applied setting (because of the necessity of using cameras or linear encoders) since rotatory encoders that are generally incorporated in flywheel devices are not suitable for this aim (Muñoz-López et al, 2022). Therefore, the use of RPE during daily monitoring could be a valid alternative to monitor flywheel exercise concentric velocity.…”

Test-Retest and Inter-Rater Reliability of a Rotary Axis Encoder-Flywheel System for the Assessment of Hip Rotation Exercises

“…The analysis of inter-rater reliability and the inclusion of the mean and peak values of velocity and force were novel aspects of this study. It could be noted that both force and velocity are widely used outcomes for monitoring performance, even in flywheel exercises [36,37]. In addition, the exercise performance may be conditioned by the patient's positioning relative to the flywheel and the instructions provided by the examiners.…”

Flywheel Eccentric Training: How to Effectively Generate Eccentric Overload

“…Different types of flywheel systems exist (Figure 1): horizontal cylinder shape (flywheel squat, flywheel leg curl, flywheel leg extension, flywheel leg press, flywheel pulley, and flywheel multigym) and vertical cone. This vertical cone, also known as the “conical pulley,” has an increasing radius from the top to the bottom (23,70). It has been shown that although a horizontal cylinder-shaped device would allow for higher forces during the eccentric phase, vertical cone-shaped devices can achieve higher speeds (70).…”

“…This vertical cone, also known as the “conical pulley,” has an increasing radius from the top to the bottom (23,70). It has been shown that although a horizontal cylinder-shaped device would allow for higher forces during the eccentric phase, vertical cone-shaped devices can achieve higher speeds (70).…”

“…To create eccentric overload, authors recommend modifying the tempo and range of motion during the eccentric phase (i.e., decelerating or slowing down at the end of the eccentric phase) (71). Horizontal cylinders and higher inertias have shown more likelihood of creating eccentric overload (61,70). Finally, experience and gender could also influence creating (or not) eccentric overload (61,116).…”