Surface wave elastography is a reliable method to correlate muscle elasticity, torque, and electromyography activity level.

Gustavo A Grinspan,Hélio V Cabral,Leonardo M L Souza,Liliam F Oliveira,Nicolás Benech,Ernesto Blanco,Sofía Aguiar

doi:10.14814/phy2.14955

Abstract

The shear elastic modulus is one of the most important parameters to characterize the mechanical behavior of soft tissues. In biomechanics, ultrasound elastography is the gold standard for measuring and mapping it locally in skeletal muscle in vivo. However, their applications are limited to the laboratory or clinic. Thus, low‐frequency elastography methods have recently emerged as a novel alternative to ultrasound elastography. Avoiding the use of high frequencies, these methods allow obtaining a mean value of bulk shear elasticity. However, they are frequently susceptible to diffraction, guided waves, and near field effects, which introduces biases in the estimates. The goal of this work is to test the performance of the non‐ultrasound surface wave elastography (NU‐SWE), which is portable and is based on new algorithms designed to correct the incidence of such effects. Thus, we show its first application to muscle biomechanics. We performed two experiments to assess the relationships of muscle shear elasticity versus joint torque (experiment 1) and the electromyographic activity level (experiment 2). Our results were comparable regarding previous works using the reference ultrasonic methods. Thus, the NU‐SWE showed its potentiality to get wide the biomechanical applications of elastography in many areas of health and sports sciences.

Highlights

Assessing the shear elasticity of skeletal muscle in vivo and in a reliable way is of great interest within different areas of life and health sciences
The goal of this work is to test the performance of the non-u ltrasound surface wave elastography (NU-SWE), which is portable and is based on new algorithms designed to correct the incidence of such effects
The lowest values were 5.57 ± 1.05 and 4.42 ± 0.27 kPa, respectively, which are in very good agreement with previous works using the ultrasonic methods since the reported values ranging from 3.11 ± 0.42 kPa (BB) and 3.05 ± 0.52 kPa (TB) (Lacourpaille et al, 2012)

Summary

Introduction

Assessing the shear elasticity of skeletal muscle in vivo and in a reliable way is of great interest within different areas of life and health sciences. There are several recent works where these methods were applied to address complex problems in muscle biomechanics, such as the load sharing between muscles, muscular fatigue, and the relation of muscle shear elasticity with joint torque and electromyography (EMG) activity level (Ateş et al, 2015; Bouillard, Hug, et al, 2012; Bouillard, Nordez, et al, 2012; Bouillard, Nordez, & Hug, 2011; Gennisson et al, 2005, 2010; Lapole et al, 2015; Nordez et al, 2009; Nordez & Hug, 2010; Yoshitake et al, 2014) These studies were performed applying ultrasound elastography and other traditional methods used in the muscle biomechanics field (e.g., isokinetic dynamometry, surface EMG). The main advantages of TE and SSI methods are that they combine high-frequency ultrasonic waves (106 Hz), which exhibit a good spatial resolution (

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