Phase-contrast MRI reveals mechanical behavior of superficial and deep aponeuroses in human medial gastrocnemius during isometric contraction

Abstract

ton VR, Sinha S. Phase-contrast MRI reveals mechanical behavior of superficial and deep aponeuroses in human medial gastrocnemius during isometric contraction. J Appl Physiol 105: 1312-1320, 2008. First published August 14, 2008 doi:10.1152/japplphysiol.90440.2008.-The behavior of the entire medial gastrocnemius (MG) superficial and deep aponeurosis structure was investigated with velocity-encoded phasecontrast, spin-tag, and three-dimensional morphometric magnetic resonance imaging. The displacements and strain of both these aponeuroses, muscle length, and the cross-sectional segment length of the deep aponeurosis were measured during isometric plantarflexion at 20% and 40% of maximal voluntary contraction (MVC). The length of the entire MG shortened during 20% and 40% MVC. All regions of interest in both aponeuroses moved proximally. Positive strain (lengthening) occurred in both ends of the deep aponeurosis and in the proximal region of the superficial aponeurosis. In contrast, negative strain (shortening) was observed in the middle region of the deep aponeurosis and in the distal region of the superficial aponeurosis. Consistent with this shortening of the deep aponeurosis length along the proximal-distal axis was expansion of the aponeuroses in the medial-lateral and anterior-posterior directions in the cross-sectional plane. It is concluded that at low to moderate force levels of isometric contraction, regional differences in strain occur along the proximal-distal axis of both aponeuroses, and some regions of both aponeuroses shorten. strain; skeletal muscle; morphology; velocity-encoded phase-contrast magnetic resonance imaging; aponeurosis DURING HUMAN MOVEMENT, force produced by muscle fibers is transmitted through tendinous tissue, that is, tendons and aponeuroses, to bones since skeletal muscle is attached to the bones via tendinous tissues at both proximal and distal ends of the muscle. These tendinous tissues play an important role as series elastic components and can store elastic energy during the movement (1, 4). Ultrasonographic techniques have suggested that during an isometric contraction the superficial and deep aponeuroses of medial gastrocnemius (MG) are homogeneously stretched along their lengths in opposite directions; the superficial aponeurosis is stretched distally, whereas the deep aponeurosis is stretched proximally (13,14). A rather different conclusion was drawn in other references in the literature (16,24,25), which pointed out that the strain properties of aponeurosis may be more complex than the ultrasound data suggest. Direct measurements of aponeurosis strain in contracting rat gastrocnemius muscle indicate inhomogeneous strain (25), and several models of contracting unipennate muscle also indicate inhomogeneous strain in the aponeuroses (16,24).Phase-contrast (PC) magnetic resonance imaging (MRI) has been used to investigate the mechanical behavior of the muscle and tendinous tissue during muscle contraction (5)(6)(7)20). The PC MRI technique has the advantage of superior sof...

Length changes of human tibialis anterior central aponeurosis during passive movements and isometric, concentric, and eccentric contractions

“…Similarly, Lieber et al (2000) found higher strains in the frog semitendinosus aponeurosis for the equivalent forces in the passive compared with the active muscle, a result that was confirmed in aponeuroses of the lateral gastrocnemius in turkeys (Azizi and Roberts 2009) Recent findings in human studies also seem to contradict the idea that aponeuroses are arranged in series with the contractile elements. Using phase contrast MRI, Kinugasa et al (2008) observed shortening in parts of the human medial gastrocnemius aponeuroses during isometric contractions at low activation levels (20 and 40% of MVC). These authors associated this shortening with the threedimensional behavior of the aponeurosis during activation which leads to transversal stretch and longitudinal shortening of the aponeurosis upon active force production.…”

Effect of tendon stiffness on the generated force at the Achilles tendon - 3D finite element simulation of a human triceps surae muscle during isometric contraction

“…The difference of the strain between the deep aponeurosis and the external tendon was observed in a FEM simulation and also in experiments (e.g., Chi et al, 2010;Magnusson et al, 2003;Kinugasa et al, 2008). In the experiments of Magnusson et al (2003), the strain of the external tendon was 5.7 times greater than the strain of the aponeurosis during isometric contraction.…”

Imaging Studies of the Mechanical and Architectural Characteristics of the Human Achilles Tendon in Normal, Unloaded and Rehabilitating Conditions

“…Figure 4 shows a 3-dimensional reconstructed image of the entire medial gastrocnemius and axial morphological MR images at 30%, 50%, and 90% locations along the proximal-distal direction under rest, at 20% maximal voluntary contraction (MVC), and at 40% MVC from www.intechopen.com one subject (Kinugasa et al 2008). At the 50% location, the deep aponeurosis exhibited greater sinuosity in the cross section as force levels increased, which resulted in a significantly greater segment length for 40% MVC (Kinugasa et al 2008). In contrast, the cross-sectional segment length of the deep aponeurosis at the 90% location decreases significantly with increasing force levels.…”

“…B: axial morphological images at 30%, 50%, and 90% locations as indicated in the 3D image at rest, 20% MVC, and 40% MVC from 1 subject. The deep aponeurosis is indicated by white lines in these axial images and reveals changes in shape and cross-sectional segmental length after force production (from Kinugasa et al 2008). …”