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Muscle morphological parameters such as fascicle length (FL), pennationangle (PA) and physiologic cross-sectional area (PCSA) can provide an insightinto the reasons of the deteriorated muscle functions caused by pathologies.This study investigates the 3D structure of the lower leg muscles using 3Dfreehand ultrasound (3DfUS). This imaging modality uses a motion capturesystem to track the position of the US probe during acquisition and thusreconstruct the structure of the tissues in 3D. In this study, two subjects werescanned on the medial gastrocnemius (MG) and tibialis anterior (TA) musclesin the lower leg using 3DfUS system. The FL and PA of the muscles werecalculated and compared with the values previously measured using diffusiontensor imaging (DTI). The results using 3DfUS were averagely 19.2% largerin FL and 2.9%larger in PA. In conclusion, 3DfUS can successfully determinemuscle morphological parameters within a physiologically acceptable range.But the differences in FL observed between the two imaging modalities werequite big, which probably was due to the differences in sample size and area.The values can also differ greatly within the 3DfUS measurements as a resultof different manipulations during data processing, and the 3DfUS protocolneeds to be further improved in future studies.

Background: Muscle thickness, pennation angle, and fascicle length describe the architecture of a muscle. These properties can be observed alongside subcutaneous fat thickness using ultrasonography; however, measurement is sensitive to the angle of the transducer against the skin. Typically, the transducer is held perpendicular to skin for imaging. Nonetheless, a convenient, reliable method to ensure transducer angle consistency has not been reported. Objectives: The purpose of this study was to determine the influence of transducer angle on muscle architecture and subcutaneous fat measurements of quadriceps muscles (vastus lateralis and rectus femoris) in healthy young adults. A secondary objective was to determine intra- and inter-rater reliability. Methods: Thirty men and women were recruited (25±2.5 years; BMI: 22.6±3.0 kg/m2). Ultrasound images were acquired from two muscles. An image was taken at an estimated perpendicular angle to the skin. Then, using a 3D-printed device with a protractor that attached to the ultrasound transducer, images were taken at measured angles 5-10˚ medial and lateral to perpendicular. Agreement and error were determined using intraclass correlation coefficients (ICCs) and standard error measurements (SEMs). Results: Good to excellent agreement was demonstrated for muscle and fat thicknesses regardless of transducer angle (ICC >0.66). Intra-rater reliability was excellent for all outcomes within both muscles (ICC >0.89). Inter-rater reliability for the rectus femoris was good to excellent for all transducer angles except for measurements of fascicle lengths at 85° (ICC: 0.33–0.99). Inter-rater reliability improved >20% for the vastus lateralis with the device. Conclusion: Measurements of muscle pennation angle and fascicle lengths, but not muscle or subcutaneous fat thicknesses, were sensitive to transducer angle. Reliability of pennation angle and fascicle lengths improved with the use of our device. Using our device, reliable muscle architecture measures can be made for the rectus femoris and the vastus lateralis in healthy young adults. / Thesis / Master of Science (MSc) / The arrangement of small muscle components, known as fascicles, can be observed in humans using ultrasound imaging. These fascicle arrangements can be measured to improve understanding of muscle function and disease processes. A potential problem of viewing muscle with ultrasound is that the angle of the probe head against the skin can alter the appearance of the muscle fascicles. The goal of this research was to improve current methods of ultrasound imaging of two thigh muscles. We have created a novel 3D-printed device to attach to the existing ultrasound probe. This 3D-printed device stabilizes the ultrasound probe head; and accurately determines the angles between the ultrasound probe head and the surface of the skin. In this study, the use of this device improved reliability of our ultrasound images by >20%. Future use of this device may improve measurements of muscle fascicles acquired with ultrasound imaging.

La parésie spastique est souvent envisagée comme une atteinte de la commande motrice, comportant une parésie de l’agoniste et une hyperactivité de l’antagoniste. Cependant, une seconde affection d’ordre musculaire - la myopathie spastique, apparait rapidement, pendant la phase aigüe après la lésion. L’hypomobilisation en position courte de certains muscles dans le contexte d’une parésie des muscles opposés s’accompagne d’une perte de leur tension longitudinale, première étape d’une cascade de transformations génétiques, structurelles, biomécaniques puis physiologiques des muscles hypomobilisés, incluant entre autres une perte de leur extensibilité et de leur longueur. Aux stades subaigu puis chronique du syndrome, les affections neurologique et musculaire coexistent, et semblent s’entretenir mutuellement.Sur le plan physiopathologique, ce travail de recherche s’est d’abord intéressé à ces intrications entre les affections neurologique et musculaire, et à la part de responsabilité potentielle de la myopathie spastique dans la fonction active. Ce premier travail a montré que le degré d’hypoextensibilité musculaire d’un antagoniste, au-delà d’un certain seuil, est corrélé au degré de perturbation de la commande motrice dirigée sur l’agoniste. La chronologie des différents événements établie dans la littérature, avec des anomalies histologiques musculaires qui apparaissent toujours avant les premières manifestions d’hyperactivité motoneuronale, amène à suggérer une responsabilité causale de la maladie du muscle dans une partie des perturbations ultérieures de la commande neuronale descendante. Ce rôle probablement essentiel de la maladie musculaire au sein de la parésie spastique doit inciter le clinicien à orienter une part significative de son traitement vers une stimulation optimale de la plasticité musculaire pour tenter de prévenir ou d’inverser le processus de myopathie spastique.Si l’étirement est depuis très longtemps une technique courante, sa capacité à augmenter durablement l’extensibilité musculaire est aujourd’hui controversée, même si ses effets à long terme, i.e. au-delà de six mois d’application quotidienne, n’ont pas été explorés.La deuxième partie, thérapeutique, de ce travail a donc été l’étude des effets à long terme d’un programme quotidien d’auto-étirements de haute intensité au sein de la méthode des Contrats d’Autorééducation Guidée, pendant un an ou plus. Il a d’abord été rétrospectivement montré que ce programme avait permis, sur trois années de suivi de sujets parétiques, une amélioration progressive importante de l’extensibilité musculaire mesurée cliniquement. Un essai randomisé contrôlé contre la kinésithérapie conventionnelle avec mesures échographiques de paramètres structuraux des muscles étirés a ensuite établi que l’application de ce programme durant un an chez des sujets atteints d’hémiparésie chronique sur AVC générait une augmentation de la longueur fasciculaire des muscles fléchisseurs plantaires, parallèlement à une amélioration de la fonction active, de façon nettement plus importante que la thérapie conventionnelle.L’ensemble de ces résultats doit participer à une meilleure prise en compte des altérations passives structurelles évolutives du muscle comme une entité nosologique, la myopathie spastique, méritant un traitement spécifique au sein de la parésie spastique, afin de limiter ses interactions avec la maladie neurologique et de réduire les déficits fonctionnels. La pratique quotidienne de postures d’auto-étirement à haute intensité, guidée par un thérapeute et auto-documentée par le patient sur un registre, peut être prescrite et réalisée sur le long terme, afin de traiter la myopathie spastique. / Spastic paresis is often understood as a neurologic disorder of the motor command that includes agonist paresis and antagonist overactivity. However, a second disorder, involving the muscle and named spastic myopathy, appears rapidly during the acute phase after the lesion. Hypo-mobilization in shortened position of some muscles of the paretic limbs, in the context of paresis of their antagonists, will reduce their longitudinal tension, which acts as the first event of a cascade of transformations involving genetic, structural, biomechanical, and then physiological mechanisms, leading to loss of muscle extensibility and length. At the subacute and chronic stages of this syndrome, the neurological and the muscular disorders coexist, seemingly feeding on each other.From a pathophysiological point of view, this research work started by exploring the entanglements between the neurological and muscular disorders, and the potential responsibility of spastic myopathy in the impairment of active function. The first study demonstrated that the loss of muscle extensibility in antagonists, when above a certain threshold, correlates with the degree of disturbance of the motor command directed to the agonist. The chronology of events established in the literature, with histological muscle abnormalities emerging always before the first expressions of motoneuronal overactivity, suggests a causal role of the muscle disorder in a part of the descending command disorder. The crucial role of the muscle disorder in the syndrome of spastic paresis should encourage clinicians to direct treatment towards techniques to stimulate muscle plasticity.Despite the classic use of muscle stretching in daily practice, its potential to increase muscle extensibility remains a subject of controversy, even though its long-term effects, i.e. over six months of daily implementation, have not been investigated. The second part of this work was thus therapeutic. We retrospectively explored the long-term effects of a daily, high load self-stretching programme within the Guided Self-rehabilitation Contract method, for at least a year. This work showed that this programme, applied over three years in paretic subjects, was increasingly associated with major gains in clinical muscle extensibility. A randomized controlled trial against conventional therapy, which used ultrasound exploration of structural parameters in the stretched muscles, demonstrated that this programme, applied over one year in subjects with stroke-induced chronic hemiparesis, enabled greater increase in plantar flexor fascicle length and active function improvement than conventional therapy.Taken together, these results will contribute to enhancing the knowledge about the evolving structural and mechanical muscle changes in spastic paresis, as a pathologic entity, spastic myopathy. Spastic myopathy needs to be specifically addressed, as it interacts with the neurological disorder and worsens functional impairment. Daily postures of high load self-stretch, guided by the therapist and self-monitored on a diary, should be prescribed and practiced over the long term, in order to treat spastic myopathy in subjects with spastic paresis.

In der vorliegenden Studie wurde daher den Einfluss exzentrischen Trainings, mit unterschiedlicher Reizmagnitude, Bewegungsgeschwindigkeit und Muskellänge bei Reizapplikation, auf die Adaptation des M. vastus lateralis (VL) untersucht. Die 31 Studienteilnehmer wurden randomisiert in zwei Trainings- und eine Kontrollgruppe aufgeteilt. Die Trainingsgruppen führten 30 Trainingseinheiten mit exzentrischem Training der Knieextensoren an einem Isokineten durch. Gruppe 1 (n=10) trainierte ein Bein mit 65% der maximalen willkürlichen isometrischen Kontraktion (MVC) und das andere Bein mit 100% MVC, bei einer Winkelgeschwindigkeit von 90°/s und einem Kniewinkel von 25°-100°. Gruppe 2 (n=10) trainierte beide Beine mit 100% MVC, ein Bein aber mit einer Winkelgeschwindigkeit von 90°/s in einem Kniewinkel von 25°-65° und das andere Bein mit 240°/s und 25°-100°. In der Pre- und Postmessung wurde die VL Muskelfaserlänge mittels Ultraschall bestimmt und die Moment-Winkel- und Leistungs-Winkelgeschwindigkeitsrelation mit einem Dynamometer erfasst. Die Ergebnisse zeigen nur für Bein mit 240°/s eine signifikante (p / The present study investigated the effects of magnitude, velocity and muscle length at which the eccentric stimulus is applied on the longitudinal adaptation of the vastus lateralis muscle (VL). The 31 participants were randomly assigned into two experimental groups to perform 30 sessions of eccentric training for the knee extensors (3 times/week) and one control group. The first experimental group (n=10) exercised one leg at 65% of maximum voluntary isometric contraction (MVC) and the second leg at 100% MVC at 90°/s from 25° to 100° knee angle on an isokinetic device (Biodex 3). The second experimental group (n=10) exercised one leg at 100% MVC at 90°/s from 25° to 65° knee angle and the other leg at 100% MVC at an angular velocity of 240°/s from 25° to 100° knee angle. In pre and post measurements the fascicle length of the VL was examined by ultrasonography and the moment-angle and power-angular velocity relationship of the knee extensors with a dynamometer. The results showed an increase (p