Effect of Acute Static Stretching on the Activation Patterns Using High-Density Surface Electromyography of the Gastrocnemius Muscle during Ramp-Up Task

Noriaki Maeda,Masanori Morikawa,Yuichi Nishikawa,Hiroaki Kimura,Makoto Komiya,Shogo Tsutsumi,Kazuki Fukui,Yukio Urabe,Tsubasa Tashiro

doi:10.3390/s21144841

Abstract

This study aimed to evaluate motor unit recruitment during submaximal voluntary ramp contraction in the medial head of the gastrocnemius muscle (MG) by high-density spatial electromyography (SEMG) before and after static stretching (SS) in healthy young adults. SS for gastrocnemius was performed in 15 healthy participants for 2 min. Normalized peak torque by bodyweight of the plantar flexor, muscle activity at peak torque, and muscle activation patterns during ramp-up task were evaluated before and after SS. Motor unit recruitment during the submaximal voluntary contraction of the MG was measured using SEMG when performing submaximal ramp contractions during isometric ankle plantar flexion from 30 to 80% of the maximum voluntary contraction (MVC). To evaluate the changes in the potential distribution of SEMG, the root mean square (RMS), modified entropy, and coefficient of variation (CV) were calculated from the dense surface EMG data when 10% of the MVC force was applied. Muscle activation patterns during the 30 to 80% of MVC submaximal voluntary contraction tasks were significantly changed from 50 to 70% of MVC after SS when compared to before. The variations in motor unit recruitment after SS indicate diverse motor unit recruitments and inhomogeneous muscle activities, which may adversely affect the performance of sports activities.

Highlights

Stretching is performed during warm-up for sports and is considered essential for optimizing performance [1,2]
Current research suggests that Static stretching (SS) decreases muscle activity and power and evokes contractile properties, thereby impacting physical performance [6]
This study aimed to evaluate motor unit recruitment during submaximal voluntary ramp contraction in the medial head of the gastrocnemius muscle (MG) by spatial electromyography (SEMG) performed after SS compared to before SS in healthy young adults

Summary

Introduction

Stretching is performed during warm-up for sports and is considered essential for optimizing performance [1,2]. It has proven to be an effective method for decreasing muscle stiffness [3], and improving joint flexibility and physical performance in activities involving jumping and dynamic balance [4]. Stretching is important for the prevention of injuries during sporting activities [5]. Current research suggests that SS decreases muscle activity and power and evokes contractile properties, thereby impacting physical performance [6]. A previous study reported greater activation deficits after SS than before SS [7]. These effects may have been due to peripheral nerve mechanisms resulting from muscle tendon stiffness [8]. A unified view on the effects of SS is lacking

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