Insights into muscle metabolic energetics: Modelling muscle-tendon mechanics and metabolic rates during walking across speeds

Prior studies have produced models to predict metabolic rates based on experimental observations of isolated muscle contraction from various species. Such models can provide reliable predictions of metabolic rates in humans if muscle properties and control are accurately modeled. This study aimed to examine how muscle-tendon model calibration and metabolic energy models influenced estimation of muscle-tendon states and time-series metabolic rates, to evaluate the agreement with empirical data, and to provide predictions of the metabolic rate of muscle groups and gait phases across walking speeds. Three-dimensional musculoskeletal simulations with prescribed kinematics and dynamics were performed. An optimal control formulation was used to compute muscle-tendon states with four levels of individualization, ranging from a scaled generic model and muscle controls based on minimal activations, to calibration of passive muscle forces, personalization of Achilles and quadriceps tendon stiffnesses, to finally informing muscle controls with electromyography. We computed metabolic rates based on existing models. Simulations with calibrated passive forces and personalized tendon stiffness most accurately estimate muscle excitations and fiber lengths. Interestingly, the inclusion of electromyography did not improve our estimates. The whole-body average metabolic cost was better estimated using Bhargava et al. 2004 and Umberger 2010 models. We estimated metabolic rate peaks near early stance, pre-swing, and initial swing at all walking speeds. Plantarflexors accounted for the highest cost among muscle groups at the preferred speed and was similar to the cost of hip adductors and abductors combined. Also, the swing phase accounted for slightly more than one-quarter of the total cost in a gait cycle, and its relative cost decreased with walking speed.Comment: 33 pages, 7 figure

Electromyographic and Joint Kinematic Patterns in Runner\u27s Dystonia.

Runner’s dystonia (RD) is a task-specific focal dystonia of the lower limbs that occurs when running. In this retrospective case series, we present surface electromyography (EMG) and joint kinematic data from thirteen patients with RD who underwent instrumented gait analysis (IGA) at the Functional and Biomechanics Laboratory at the National Institutes of Health. Four cases of RD are described in greater detail to demonstrate the potential utility of EMG with kinematic studies to identify dystonic muscle groups in RD. In these cases, the methodology for muscle selection for botulinum toxin therapy and the therapeutic response is discussed. Lateral heel whip, a proposed novel presentation of lower-limb dystonia, is also described

Kinetic, kinematic and electromyographic analysis of cranial cruciate ligament rupture using a monopolar radiofrequency energy model

2011 Summer.Includes bibliographical references.Canine cranial cruciate ligament rupture (CCLR) is a common cause of pain and lameness in dogs that leads to abnormal pelvic limb biomechanics and ultimately to the development of stifle osteoarthritis (OA). Traditional research into the causes of CCLR has focused on instability secondary to failure of the passive structures within the joint. The purpose of this project was to recognize the role of dynamic components as possible contributors to CCL disease, such as neuromuscular dysfunction of muscles (dynamic stabilizers) surrounding the stifle joint. The present studies were performed to characterize alterations in muscle activity in the limb with CCLR and intact contralateral pelvic limbs, as well as measure biomechanical, clinical and physiologic parameters in all four limbs in dogs with subacute, acute and chronic CCLR (within the same dog during the study). Monopolar radiofrequency energy (MRFE) provided a unique model of CCL injury in which to assess subclinical timeframes. Electromyographic (EMG) parameters, collected simultaneously with ground reaction forces and kinematics, were assessed bilaterally within the vastus lateralis, biceps femoris and gastrocnemius muscles at 6 timepoints post MRFE-induced CCL injury and subsequent rupture. The treated limb denotes the pelvic limb that received MRFE surgery and subsequently ruptured the CCL. The untreated limb refers to the contralateral, non-surgical pelvic limb. Kinematic compensations showed an increase in stifle flexion in the untreated limb compared to the treated limb at all time points post CCLR. Kinetic variables were altered in the treated pelvic limb compared to the untreated limbs post CCLR. No compensatory changes in kinetic or kinematic variables were found in the thoracic limbs at any point post CCL injury or rupture. This study provided a qualitative description of muscle activity post CCL injury and subsequent rupture. No significant differences were found in muscle onset, activation duration or percentage of peak amplitude normalized to baseline between the treated and untreated pelvic limbs at all time points. Clinical and physiologic outcome parameters were collected concurrently throughout the duration of the study to evaluate their association with CCL injury and rupture. Joint effusion was the only outcome parameter associated with subclinical CCL injury. However, the majority of these parameters, such as pain, lameness, range of motion, cranial drawer test and radiography, were associated with subsequent rupture of the CCL. In conclusion, kinematic variables, specifically femorotibial flexion angles, were decreased in the contralateral pelvic limb post CCLR, with minimal changes in subclinical time points at 2 and 4 weeks post MRFE-induced CCL injury. Future studies with larger samples sizes are needed to confirm EMG activity in stabilizing muscles of the stifle to further investigate the role of neuromuscular control in stifle stability. Several outcome parameters such as thigh circumference, pain, lameness, range of motion, cranial drawer test and radiography, and have been shown to be useful in identifying the presence of CCLR, but not subclinical CCL disease

Identifying Primary and Compensatory Abnormalities using Single and Double Limb Support Phase Gait Analysis

This study describes biomechanical forces on bipedal gait in 2 phases - on both limbs in double limb support (DLS) and while on one limb is in single limb support (SLS) with the opposite limb in swing. Primary abnormalities are muscle activity abnormalities which directly cause abnormalities in gait. Secondary abnormalities are compensatory muscle activities which try and correct primary abnormalities. This study describes kinetic, kinematic and dynamic EMG characteristics of DLS and SLS using 36 gait data cycles from 18 gait collections. DLS/SLS analysis is used to identify primary and secondary abnormalities in gait. The stability function of DLS is commonly affected by knee and ankle power absorption and this is due to a combination of impaired voluntary control at the knee in DLS1 and spasticity at the ankle in DLS2. The primary abnormality in SLS is spasticity but this spasticity might actually be compensatory or beneficial. Swing is characterized by mostly normal kinematic, EMG and kinetic activity. The hip is relatively spared especially with regards to EMG and range of movement. DLS/SLS analysis is a useful tool in diagnosing primary and secondary abnormalities in gait. CONCLUSIONS: 1. SLS/DLS analysis may be a useful technique to identify abnormalities caused by one limb upon the other at the same point in time and to differentiate between primary and secondary abnormalities of gait. 2. The stability function of double limb support phase is commonly affected by knee and ankle power absorption and this is due to a combination of impaired voluntary control at the knee and spasticity at the ankle in DLS. 3. DLS1 absorption abnormalities are primarily at the knee and are probably due to impaired voluntary control. 4. DLS2 absorption abnormalities are primarily at the ankle and are probably due to spasticity and co-contraction. 5. The primary abnormality in SLS is spasticity but this spasticity might actually be compensatory or beneficial. 6. Swing is characterized by mostly normal kinematic, EMG and kinetic activity. 7. The hip is relatively spared especially with regards to EMG and range of movement. 8. A larger study with randomisation and blinding if possible is needed to confirm the findings of this study. This study will help in calculation of power and appropriate sample size required

Coordination of the lower extremity muscles during gait transitions

Often the approach to investigating muscular coordination during transitions entailed conducting tests at speeds held constant. This study investigated muscular activity during continuously changing speeds in order to further detail and quantify neuromuscular changes during gait transitions. Twelve healthy adults, 18-41 years of age, were recruited as participants. Informed consent was obtained. Gait transitions were induced by the speed of the treadmill changing with constant acceleration. Reflective markers were placed on anatomical landmarks of the hip, knee,ankle, heel, and 5 th metatarsal joint. Bipolar surface electrodes were positioned on the subjects’skin over the muscular bellies of the gluteus maximus (GM), rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius (GAS), and soleus (SOL). Electromyographic (EMG) data were collected at 960 Hz. Five transition trials were conducted for both progression modes: walk-to-run (WR) and run-to-walk (RW), and five interval trials were collected for both gaits at constant speeds. Five steps preceding the gait transitions were analyzed. The mean of recorded transition speeds (MTS) was calculated from the prior transition trials. There were five different constant speed trials for walking (WC) and running (RC); the speeds were MTS - 0.6, MTS - 0.3, MTS, MTS + 0.3, and MTS + 0.6 mph. Cross-correlation comparisons and discrete parameters of the EMG activity ensemble curves were examined across trials and conditions. Two factor (condition and trial) repeated measures ANOVA was employed for statistical analysis (á = .05). For the correlation parameters, significant running condition/trial interactions were observed for all muscles. Significant condition/trial interactions were revealed for the discrete parameters concerning activation magnitude (GM, RF, VL, TA, GAS, and SOL)and duration (RF, GAS, and SOL) for both walking and running. EMG activity intensity and duration in some muscles changed with the locomotion speed in a quadratic fashion, which was only observed in transition related trials. These results indicate that neuromuscular changes occurred steps before the observed gait transition and that changing velocity induces gait transition related behavior that cannot be observed with constant velocity in the same range

EMG-Normalised Kinase Activation during Exercise Is Higher in Human Gastrocnemius Compared to Soleus Muscle

In mice, certain proteins show a highly confined expression in specific muscle groups. Also, resting and exercise/contraction-induced phosphorylation responses are higher in rat skeletal muscle with low mitochondrial content compared to muscles with high mitochondrial content, possibly related to differential reactive oxygen species (ROS)-scavenging ability or resting glycogen content. To evaluate these parameters in humans, biopsies from soleus, gastrocnemius and vastus lateralis muscles were taken before and after a 45 min inclined (15%) walking exercise bout at 69% VO2max aimed at simultaneously activating soleus and gastrocnemius in a comparable dynamic work-pattern. Hexokinase II and GLUT4 were 46–59% and 26–38% higher (p<0.05) in soleus compared to the two other muscles. The type I muscle fiber percentage was highest in soleus and lowest in vastus lateralis. No differences were found in protein expression of signalling proteins (AMPK subunits, eEF2, ERK1/2, TBC1D1 and 4), mitochondrial markers (F1 ATPase and COX1) or ROS-handling enzymes (SOD2 and catalase). Gastrocnemius was less active than soleus measured as EMG signal and glycogen use yet gastrocnemius displayed larger increases than soleus in phosphorylation of AMPK Thr172, eEF2 Thr56 and ERK 1/2 Thr202/Tyr204 when normalised to the mean relative EMG-signal. In conclusion, proteins with muscle-group restricted expression in mice do not show this pattern in human lower extremity muscle groups. Nonetheless the phosphorylation-response is greater for a number of kinase signalling pathways in human gastrocnemius than soleus at a given activation-intensity. This may be due to the combined subtle effects of a higher type I muscle fiber content and higher training status in soleus compared to gastrocnemius muscle

Muscle co-activation during gait in children with cerebral palsy

La paralysie cérébrale (PC) est un trouble non progressif causé par une lésion cérébrale. La PC survient tôt dans la vie et présente une atteinte hétérogène et une altération fonctionnelle. Chez les personnes atteintes de PC, les modifications du Contrôle neuronal et des muscles entraînent des modifications permanentes de la fonction motrice, entraînant des déficits de mouvement. L'une des raisons des patrons de marche atypiques chez les enfants atteints de PC est l'altération l'activation musculaire. Un niveau anormal d'activation simultanée des muscles agonistes et antagonistes des muscles agonistes et antagonistes entourant une même articulation la même articulation empêche une performance de marche optimale chez les enfants atteints de PC. Ce phénomène est connu sous le nom de co-contraction musculaire (CoM) ou de co-activation musculaire (CaM) dans toutes les études. L'identification des schémas musculaires les plus détériorés, à savoir CoM/CaM, chez les enfants atteints de PC est essentielle pour une rééducation efficace de la marche. L'objectif de ce projet de maîtrise était donc de distinguer CoM/CaM chez les enfants atteints de PC de leurs pairs en développement typique (DT) pendant la marche. Cet objectif a été atteint en deux étapes ; Premièrement, nous avons décrit la CoM/CaM chez les personnes atteintes de PC via la réalisation d'une revue de littérature ; Ensuite, nous avons appliqué nos résultats de la première étape à une étude transversale pour comparer CoM/CaM pendant la marche entre des enfants atteints de CP et de DT. Une revue de littérature suivant la méthodologie en 6 étapes du Joanna Briggs Institute a été effectué. Les bases de données ont été consultées à l'aide de mots-clés pertinents. Toutes les études publiées sur CoM/CaM chez les personnes atteintes de PC pendant la marche ont été recueillies. Après un examen de la pertinence des titres et des résumés, un deuxième examen des textes intégraux des sources par deux examinateurs a été appliqué. Enfin, les données ont été extraites des articles inclus (n=21). Ensuite, à l'étape suivante, les principales méthodes utilisées pour quantifier la MCa identifiées à l'étape précédente ont été codées dans Matlab (The Mathworks Inc., Natick, États-Unis) et appliquées à nos données de 12 enfants atteints de CP et 23 enfants TD. Nous avons comparé le CaM moyen de deux groupes de muscles de la cuisse et de la jambe (Rectus Femoris (RF)/Semitendinosus (ST) et Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectivement) via des tests t non appariés (ou son équivalent non paramétrique). La revue de littérature a suggéré une CaM plus élevée chez les personnes atteintes de PC par rapport à leurs pairs en bonne santé dans toutes les études. Bien qu'il y ait eu une terminologie et des approches méthodologiques incohérentes, nous avons pu discriminer les terminologies (c'est-à-dire CoM et CaM) en fonction des méthodologies de calcul (c'est-à-dire moment et EMG) utilisées par les études. En outre, cette étude nous a permis de résumer les modèles de CaM chez les individus atteints de PC et d'identifier la relation entre certains des paramètres de marche avec CaM. Enfin, les résultats de cette étude ont révélé des informations précieuses concernant les lacunes de la recherche dans ce domaine. La deuxième étude a identifié une augmentation de la CaM pendant la marche (la foulée entière, la phase d’appuie et la phase oscillante) chez les enfants atteints de PC par rapport à leurs pairs TD. Cette augmentation n'a été observée que dans les muscles de la jambe (pendant la phase d’appuie et la phase oscillante) et dans les muscles de la cuisse (pendant la phase oscillante) lorsque nous avons normalisé les signaux d'électromyographie. Les groupes CP et DT n'avaient pas de CaM différent en utilisant l'EMG normalisé pour l'ensemble de la foulée. Cette différence met en évidence l'effet de la normalisation EMG sur les valeurs de CaM. De plus, les enfants avec le niveau II du système de classification de la fonction motrice globale (SCFMG) avaient un CaM plus élevé dans les muscles de la cuisse pendant le swing que ceux avec le niveau I. Dans l'ensemble, ce projet de maîtrise révèle de nouvelles preuves soutenant une plus grande CaM chez les enfants atteints de PC par rapport à DT pendant la marche. Néanmoins, il est important d'étudier la CaM dans différentes phases de marche car elle affecte la comparaison entre les groupes. En outre, ce projet justifie l'importance de la méthodologie (par exemple, le traitement EMG et le calcul CaM) dans les études CaM. Plus précisément, il est fort probable que les résultats changent avec différentes approches de normalisation EMG. De plus, les enfants atteints de SCFMG I et II peuvent éprouver différents niveaux de CaM pendant la phase oscillante. Davantage de comparaisons dans des recherches futures, telles qu'entre les SCFMG I, II et III dans la PC hémiplégique et diplégique pendant les sous-phases de la marche (le contact initial, le « mid-stance »), peuvent fournir de meilleures informations sur les modèles de CaM dans cette population.Cerebral palsy (CP) is a nonprogressive disorder caused by a brain injury. CP occurs early in life, before, during, or after birth, and has heterogeneous involvement and functional impairment. In individuals with CP, changes in neural drive and muscles lead to lifelong changes in motor function, leading to movement deficits. One of the reasons for atypical gait patterns in children with CP is altered muscle activation patterns. An abnormal level of simultaneous activation of agonist and antagonist muscles crossing the same joint prevents optimal gait performance in children with CP. This phenomenon is known as muscle co-contraction (MCo) or muscle co-activation (MCa) across studies. Identification of the most deteriorated muscular patterns, namely, MCo/MCa, in children with CP is vital for effective gait rehabilitation. The objective of this master’s project, therefore, was to distinguish MCo/MCa in children with CP from their typically developing (TD) peers during gait. This objective was achieved through two studies; first, we described MCo/MCa in individuals with CP via the conduction of a scoping review; then, we applied our findings to inform a cross-sectional study to compare MCo/MCa during gait between children with CP and TD. A scoping review following the 6-stage Joanna Briggs Institute methodology was conducted. Databases were searched using relevant keywords. All published studies on MCo/MCa in individuals with CP during gait were collected. After title and abstract relevance screening, a second screening for the full texts of the sources by two reviewers was applied. Finally, data were extracted from the included articles (n=21). Then, leading methods used to quantify MCa identified from the previous study were coded in Matlab (The Mathworks Inc., Natick, USA) and applied to our data from 12 children with CP and 23 TD children. We compared the average MCa of two thigh and shank muscle groups Rectus Femoris (RF)/Semitendinosus (ST) and Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectively, via unpaired t-tests (or its non-parametric equivalent). According to our scoping review, higher MCa in individuals with CP compared to healthy peers across studies was found. Although there were inconsistent terminology and methodological approaches, we could discriminate terminologies (i.e., MCo and MCa) according to the methodologies in the calculation (i.e., moment and EMG) used by studies. Also, this study enabled us to summarize MCa patterns within individuals with CP and identify the effect of the some of the gait parameters on MCa. Finally, the findings of this study revealed valuable information regarding the research gaps in this area. The second study identified increased MCa around the knee and ankle joints for the following muscles (i.e., RF/ST and TA/LG, respectively) during walking (i.e., entire stride, stance, and swing) in children with CP compared to their TD peers. This increase was seen only in shank muscles (i.e., during stance and swing) and in thigh muscles (i.e., during the swing) when we normalized electromyography (EMG) signals. CP and TD groups did not have different MCa using normalized EMG for the entire stride. This difference highlights the effect of EMG normalization on MCa values. Also, children with Gross Motor Function Classification System (GMFCS) level II had higher MCa around the knee during swing than those with level I. Overall, this master’s project reveals new evidence supporting greater MCa in children with CP compared to TD peers during walking. Nevertheless, it is recommended to investigate MCa within different gait phases as it affects the comparison across groups. Also, this project justifies the importance of methodology (e.g., EMG processing and MCa calculation) in MCa studies. More specifically, it is likely that the results alter with different EMG normalization approaches. Moreover, children with GMFCS I and II can experience various levels of MCa during the swing phase. More comparisons in future research, such as between GMFCS I, II, and III in hemiplegic and diplegic CP during gait sub-phases (i.e., initial stance, mid-stance), can provide better information regarding MCa patterns in this population

Aging effects on neuromuscular activity in karate practitioners

P. 203-213El envejecimiento conduce a una disminución general de las funciones corporales que afecta a la calidad de vida. La práctica deportiva se recomienda como un medio para atenuar el impacto del proceso de envejecimiento. El objetivo de este estudio fue identificar y analizar la actividad neuromuscular y sus patrones en los practicantes de karate activos y evaluar los efectos del proceso de envejecimiento. Dos grupos de practicantes de karate masculinos de cinturón negro, uno con nueve practicantes mayores de 50 años y el otro con 21 practicantes de entre 20 y 30 años de edad realizaron la patada frontal mae-geri. Se recogieron datos cinemáticos y electromiográficos de cinco músculos de la pierna derecha. Los resultados mostraron dos períodos distintos de activación muscular en el rendimiento de mae-geri, con patrones de actividad muscular similares entre los grupos. Sin embargo, se encontraron algunas diferencias en el inicio y la compensación de la actividad de los músculos, en la media cuadrática de la raíz y en los periodos de retraso y contracción entre músculos. Esas diferencias indicaron que el envejecimiento afecta la actividad neuromuscular en el rendimiento de mae-geri de los practicantes de karate más antiguos. Sin embargo, los resultados mostraron que la práctica de karate a lo largo de la vida puede preservar la calidad de la actividad neuromuscular en los practicantes de mayor edad cuando realizan una patada, y esto podría asociarse con beneficios para equilibrar el controlS

INDUCED ANTERIOR CRUCIATE LIGAMENT CREEP INFULENCES GROUND REACTION FORCES AND MUSCLE ACTIVATION IN WALKING

Prolonged loading of the anterior cruciate ligament (ACL) influences thigh muscle activity during walking. The resulting neuromuscular responses of the thigh musculature and ground reaction forces (GRF) during gait initiation after ACL loading are determined. PURPOSE: To observe electromyography (EMG) activity of thigh muscles and GRF during gait initiation before and after static loading of the ACL. METHODS: Eleven healthy individuals (5 male, 6 female; aged 21.6 ± 2.9 years, height 1.69 ± 0.10 m, mass 69.5 ± 12.3 kg) with no history of lower extremity pain/injury participated. Participants were seated while the left knee was flexed to 90º and secured to prevent movement. Maximal voluntary isometric contractions were performed in knee flexion and extension. A padded cuff was then fitted around the proximal lower leg, and a cable was fixed around the pad. The cable ran through a pulley system and loaded the leg for 10 min with a 200 N load for males and 150 N load for females respectively. Gait was initiated with the left leg five times immediately before and after static loading. EMG of rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and semimembranosis (SM) were collected. GRFs were normalized to body weight of the individual and analyzed during the first step. One way analysis of variance (ANOVA) was used to identify changes between pre and post-loading steps during the first 50% of the stance phase. Alpha was set at \u3c 0.05. RESULTS: Average EMG of RF was increased (p\u3c 0.05) but did not change significantly in VL, VM, BF and SM muscles from pre to post walking trials. Peak Fy and Fz were not statistically significant (p \u3e 0.05) during the post-walking trials. Peak timing of each muscle during heel contact did not vary significantly after loading the knee joint. No significant difference was found in average Fx, Fy and Fz forces during the post-walking trials. Rate of force development changed, but not uniformly between the participants and the change was not statistically significant (p \u3e 0.05). CONCLUSION: The results of the study conclude that there is a change in the thigh muscle activity from pre to post walking trials after loading the knee joint. Statistically significant change was seen in RF muscle. GRF did not show any significant difference between the trials. Thus the induced ACL creep influences the thigh muscle activity in walking, and active individuals should try to avoid ligamentous creep and include frequent rest periods in order to have a higher level of performance, as well as reduce the risk of injury