Muscle Activation Sequence in Flywheel Squats.

Darjan Spudić,Michael David Burnard,Nejc Šarabon,Darjan Smajla

doi:10.3390/ijerph18063168

Abstract

Background: Muscle coordination is important for rational and effective planning of therapeutic and exercise interventions using equipment that mimics functional movements. Our study was the first to assess muscle coordination during flywheel (FW) squats. Methods: Time-of-peak electromyographic activation order was assessed separately for 8, 4, and 3 leg muscles under four FW loads. A sequential rank agreement permutations tests (SRA) were conducted to assess activation order and Kendall’s tau was used to assess the concordance of activation order across subjects, loads and expected order of activation. Results: SRA revealed a latent muscle activation order at loads 0.05, 0.075, and 0.1, but not at 0.025 kg·m2. Kendall’s tau showed moderate-to-strong concordance between the expected (proximal-to-distal) and the observed muscle activation order only at a load 0.025 kg·m2, regardless of the number of muscles analyzed. Muscle activation order was highly concordant between loads 0.05, 0.075, and 0.1 kg·m2. Conclusions: The results show a specific role of each muscle during the FW squat that is load-dependent. While the lowest load follows the proximal-to-distal principle of muscle activation, higher loads lead to a reorganization of the underlying muscle coordination mechanisms. They require a specific and stable muscle coordination pattern that is not proximal-to-distal.

Highlights

Flywheel inertial resistance exercise received attention in recent years due to its many positive effects on athletic performance variables [1,2,3,4,5,6,7] and injury prevention in sport [8,9,10]
Exclusion criteria consisted of chronic diseases or acute injuries that could interfere with the testing, : systemic, cardiac and/or respiratory diseases or neuro-muscular disorders, knee injuries, low back pain history or acute injuries in the last 6 months that could in any way negatively affect the maximal squatting performance
It must be said that many groups have already argued why it is a prudent idea to optimize different forms of training and testing in sports and therapy

Summary

Introduction

Flywheel inertial resistance exercise received attention in recent years due to its many positive effects on athletic performance variables (change of direction, jumping, and sprinting) [1,2,3,4,5,6,7] and injury prevention in sport [8,9,10]. An underlying neural mechanism for improvements of mechanical variables can be assessed by surface electromyography (EMG) [21,22] They can be divided into single-joint or, more complex, multi-joint, or whole-body neural adaptations [22]. Kendall’s tau showed moderate-to-strong concordance between the expected (proximal-to-distal) and the observed muscle activation order only at a load 0.025 kg·m2 , regardless of the number of muscles analyzed. While the lowest load follows the proximal-to-distal principle of muscle activation, higher loads lead to a reorganization of the underlying muscle coordination mechanisms. They require a specific and stable muscle coordination pattern that is not proximal-to-distal

Objectives

Methods

Discussion

Conclusion