Length-force characteristics of in vivo human muscle reflected by supersonic shear imaging

Abstract

Recently, an ultrasound-based elastography technique has been used to measure stiffness (shear modulus) of an active human muscle along the axis of contraction. Using this technique, we explored 1) whether muscle shear modulus, like muscle force, is length dependent; and 2) whether the length dependence of muscle shear modulus is consistent between electrically elicited and voluntary contractions. From nine healthy participants, ankle joint torque and shear modulus of the tibialis anterior muscle were measured at five different ankle joint angles during tetanic contractions and during maximal voluntary contractions. Fascicle length, pennation angle, and tendon moment arm length of the tetanized tibialis anterior calculated from ultrasound images were used to reveal the length-dependent changes in muscle force and shear modulus. Over the range of joint angles examined, both force and shear modulus of the tetanized muscle increased with increasing fascicle length. Regression analysis of normalized data revealed a significant linear relationship between force and shear modulus (R(2) = 0.52, n = 45, P < 0.001). Although the length dependence of shear modulus was consistent, irrespective of contraction mode, the slope of length-shear modulus relationship was steeper during maximal voluntary contractions than during tetanic contractions. These results provide novel evidence that length-force relationship, one of the most fundamental characteristics of muscle, can be inferred from in vivo imaging of shear modulus in the tibialis anterior muscle. Furthermore, the estimation of length-force relationship may be applicable to voluntary contractions in which neural and mechanical interactions of multiple muscles are involved.

Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction

“…Shear modulus of LG decreased slightly during a 16 N·m dorsiflexing effort (15.0 ± 0.3 kPa) but significantly increased with a 48 N·m plantar-flexing effort (140.4 ± 0.3 kPa). Since the muscles they studied were different from ours, their results could not be directly compared with ours [28]. However, our conclusion about the relationship between the increasing muscle stiffness and the increasing absolute torque was in good agreement with theirs.…”

“…Few studies have been reported to investigate the relationship between VI shear modulus and knee joint angle, especially under different step isometric contraction levels. Sasaki et al [28] reported that, with the increase in the ankle joint angle, the shear modulus of TA measured by SSI also increases when performing submaximal voluntary contractions. This result is in agreement with ours.…”

Passive material properties of stroke-impaired plantarflexor and dorsiflexor muscles

“…Recently, shear wave (SW) ultrasound elastography has been used to quantify muscles stiffness in a variety of lower extremity 13,14 and upper extremity muscles in healthy individuals 15–18 . SuperSonic Imaging (SSI) uses acoustic forces to induce SWs through the tissue and tracks the propagation of the SWs using ultra-fast ultrasonic imaging to calculate SW velocity 19 .…”

Acute effect of wearing compression stockings on lower leg swelling and muscle stiffness in healthy young women

“…Instead, we have reported the repeatability (ICC and CV) of measurements, which were generally very high. The high within-and between-day reliability of tape measure (Harrelson et al, 1998), water displacement volumetry (Brijker et al, 2000;Moholkar & Fenelon, 2001;Pasley & O'Connor, 2008), segmental bioelectrical impedance analysis (Yamada et al, 2010(Yamada et al, , 2017, and ultrasound shearwave elastography (Lacourpaille et al, 2012;Sasaki et al, 2014) has also been reported elsewhere. Thus, it is highly unlikely that the lack of control condition seriously affects the significance of our findings.…”

“…To evaluate changes in muscle stiffness, ultrasound shear-wave elastography (Nordez & Hug, 2010;Bouillard et al, 2011;Lacourpaille et al, 2012Lacourpaille et al, , 2014Sasaki et al, 2014) was used to determine shear modulus along the longitudinal axis of the tibialis anterior and medial gastrocnemius muscles. Briefly, this technique involves generation of mechanical shear wave by focusing ultrasound beam, ultrafast (up to 20 kHz) imaging of tissues during the shear wave propagation, and calculation of shear wave propagation velocity (Bercoff et al, 2004).…”