Abstract
This study aims to explore the possibility of assessing muscle stress state using shear wave elastography (SWE). Eight healthy males participated in the measurements, and the Young's modulus of 10 leg muscles of each participant were measured in six standard positions: lying, sitting, and four quasi-static walking postures. The contributions of each muscle in the four quasi-static walking postures were examined, and the relationship between the Young's modulus and simultaneously recorded plantar pressure was preliminarily explored for the most significant muscles. Results indicate that ICC3,1 ranges from 0.941 to 0.998, and 95% CI is in the range 0.909-0.999, CV ranges from 1.45% to 9.5%, and SEM ranges from 0.026 kPa to 0.824 kPa for all the tested muscles. This indicates that the Young's modulus of the muscles, measured by SWE, showed excellent retest reliability. In the lying and sitting positions, significant differences were observed in Young's modulus of 9 muscles with the only exception of biceps femoris (BF). In the heel strike and push off positions, strong linear relationships were found between the plantar pressure and Young's modulus of gastrocnemius medialis (GM) suggesting that muscle SWE measurement may be a good indicator of ground reaction forces. This study demonstrates that the SWE measures of the muscle Young's modulus can be used to reliably reflect the quantitative change in the stiffness of a muscle at different positions, and may also be employed to estimate the ground reaction forces and muscle stress state. Although this is a great progress in studying muscle force, it is still a great challenge to measure the Young's modulus of muscle and noninvasively evaluate the muscle force in vivo using SWE.
Highlights
Muscles play the role of an actuator in a human musculoskeletal system, facilitating a range of complex movements
The results indicate that the ICC3,1 ranged from 0.941 to 0.998 and the 95% confidence interval (95% CI) is between 0.909– 0.999, coefficient of variation (CV) ranged from 1.45% to 9.5%, and SEM ranged from 0.026 kPa to 0.824 kPa for all the tested muscles
The Kendall’s W tests results are shown in Table 2, and it can be seen that the coefficient of concordance W of muscle Young’s modulus evaluated by operators are all higher than 0.872, and the results showed that the evaluation standards between operators are consistent
Summary
Muscles play the role of an actuator in a human musculoskeletal system, facilitating a range of complex movements. Mechanical characteristics of muscles during movements are research hotspots in biomechanics and bionics. In-depth study of the assessment of muscle force is conducive to extend the range of biomechanics and to promote the development of bionic mechanical design, biomedicine, competitive sports, and other disciplines [1]–[3]. Previous studies have examined the torque and stiffness of human muscles in lower extremities in vivo during passive stretching by. The associate editor coordinating the review of this manuscript and approving it for publication was Giulia Matrone. The aforementioned measurements are influenced by various factors, such as synergistic muscles, aponeurosis, tendons, and ligaments, and it is difficult to accurately evaluate the passive characteristics of a single muscle [7]
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