This is Part A. / Abstract Not Provided. / Thesis / Master of Engineering (MEngr)

The purpose of this study was to relate femoral venous plasma potassium concentrations ([K⁺]) following a fatiguing submaximal isometric quadriceps contraction, to the excitability of the muscle cell membrane as assessed by the compound muscle action potential (M-Wave) . Ten healthy male volunteers (22. 0 ± . 5 yrs) performed a unilateral 3 minute (min) sustained isometric quadriceps contraction at 30% of their maximum voluntary contraction (MVC) . M-Waves, peak evoked twitch torque, plasma lactate concentration ([La⁻]), and plasma potassium concentration ([K⁺]) were measured before, and at predetermined times over the course of a 15 min recovery period following the fatigue paradigm. Immediately post-exercise, twitch torque decreased to 58% of baseline, femoral venous [La⁻] had risen to 10 ± 0.8 mmol/1, and [K⁺] was significantly increased from 4.0 ± 0.1 mmol/1 to 5.9 ± 0.2 mmol/1. M-Wave amplitude illustrated a trend for potentiation increasing 9.5%-from 13.9 ± 2.4 mV pre-exercise, to 15.3 ± 2.8 mV at 1 min 20 seconds post-exercise. M-Wave area exhibited a similar trend from baseline, but values showed no statistical significance during this time. These results suggest that in spite of increased extracellular [K⁺] following this type of fatiguing exercise, muscle membrane excitability is maintained, which is probably due to the electrogenic nature of the highly active Na⁺ /K⁺ pump. This study was supported by the Natural Sciences and Engineering Research Council of Canada. / Thesis / Master of Science (MSc)

Introduction/problématique : En post-AVC, il est fréquent d'observer l'hyperactivité involontaire du muscle droit antérieur du quadriceps (DAQ) attribué, à tort ou à raison, au phénomène de spasticité, puisque les outils d'évaluation utilisés en clinique pour mesurer ce phénomène ont démontré certaines lacunes métrologiques. Des études récentes montrent que le seuil du réflexe d'étirement tonique (SRET) serait plus fiable pour quantifier la spasticité. Par contre, le SRET est développé pour évaluer la spasticité durant des mouvements passifs. Or, la spasticité fluctue avec les différentes vitesses de marche. Préalablement à la mesure du SRET du DAQ lors de la marche, il est nécessaire de mieux comprendre le taux d'utilisation musculaire (TUM) du muscle en activité fonctionnelle. L'engagement cible du présent projet est de déterminer le TUM du muscle DAQ du membre inférieur atteint/non-atteint d'hyperactivité musculaire à différentes vitesses de marche. Méthodologie : La population cible concernait des participants post-AVC (n=5) déambulant et présentant de la spasticité au muscle DAQ. Le TUM (%) a été calculé via des données recueillies sur le muscle DAQ (bilatéralement), à l'aide de l'électromyographie de surface (EMGs), au cours de trois vitesses de marche (lente, normale, rapide). Résultats : Le TUM (%) du DAQ atteint de spasticité diminue de manière plus marquée avec l'augmentation de la vitesse de marche (32.11 % d'augmentation à vitesse lente versus 17.64 % d'augmentation à vitesse rapide). Il a été remarqué une différence clinique de 51 % du TUM entre le membre atteint/non-atteint de spasticité à vitesse de marche lente, 18% à vitesse normale et > 1 % à vitesse rapide. Finalement, il a été observé une taille d'effet moyenne (d : 0.67) entre les TUM du DAQ atteint/non-atteint à vitesse de marche lente et faible à vitesse normale et rapide (d : 0.39 et 0.001 respectivement). Conclusion : Cette étude tend à supporter les observations des praticiens en réadaptation selon laquelle une augmentation de la vitesse de marche améliorerait la fonction des membres inférieurs en contexte d'hyperactivité musculaire attribuée à la spasticité. Cependant, ces résultats vont à l'encontre du concept de vélodépendance attribuable à la spasticité qui devrait se traduire sur le plan clinique par une augmentation de l'hyperactivité musculaire lors de vitesse de marche rapide. Les qualités métrologiques des tests cliniques demeurent problématiques ; en effet, la nécessité d'identifier la spasticité par une approche plus rigoureuse reste pertinente. La vitesse de marche lente serait-elle la plus appropriée pour identifier la spasticité avec la méthode du SRET au niveau du DAQ durant la marche, en post-AVC? / Introduction/problem: It is common, post-stroke, to observe involuntary hyperactivity of the rectus femoris (RF) muscle, limiting gait patterns and generally attributed, rightly or wrongly, to spasticity because the assessment tools used in the clinic to measure this phenomenon have shown certain metrological shortcomings. Recent studies show that the Tonic Stretch Reflex Threshold (TSRT) would be more reliable to quantify spasticity, despite the fact that it was developed to assess this during passive movements. However, spasticity is likely to fluctuate with different walking speeds. Prior to measuring the TSRT of the RF while walking, it is necessary to better understand the functional significance of its muscular utilization rate (MUR). The target commitment of this project is to determine the MUR of the RF muscle of the lower limb with/without muscle hyperactivity at different walking speeds. Methodology: The target population concerns post-stroke ambulatory participants (n=5) presenting spasticity in the DAQ muscle of the lower limb. The MUR (%) was calculated from data collected on the RF muscle (bilaterally), using surface electromyography (EMGs), at three different walking speeds (slow, normal, fast). Results: The MUR (%) of the RF decreases more markedly for the limb with spasticity at increased walking speed (32.11% at slow speed compared to 17.64% at fast speed). A clinical difference of 51% of the MUR between the affected/unaffected limb is noted at slow walking speed, compared to > 1% at fast walking speed. Finally, a medium effect size (d: 0.67) is observed between the TUM of the DAQ, with and without spasticity, at slow walking speed. Conclusion: This study tends to support the observations of rehabilitation practitioners to the effect that an increase in walking speed would improve the function of the lower limbs in the context of muscular hyperactivity attributed to spasticity. On the other hand, these results go against the concept of velocity-dependence attributable to spasticity, which should translate clinically into an increase in muscle hyperactivity during fast walking. The metrological qualities of clinical tests are problematic; in fact, the need to identify spasticity by a more qualified approach remains relevant. Would slow walking speed be the most appropriate to identify spasticity with the SRET method at the DAQ level during gait, post-stroke?

A relação entre eletromiografia e força é objeto de numerosos estudos, porém tal relação ainda não está totalmente elucidada e necessita de uma melhor fundamentação. Uma possível razão para as divergências entre esses estudos reside na dificuldade em determinar a força de um músculo individualmente de forma direta. Dentro deste contexto, procurou-se utilizar a análise do sinal eletromiográfico, associada a um modelo biomecânico do segmento articular para a avaliação das forças internas do músculo. O objetivo do presente trabalho é avaliar o comportamento eletromiográfico do músculo quadríceps durante exercícios isométricos e isotônicos concêntricos e correlacioná-lo com a força muscular, calculada através de simulações, usando modelos biomecânicos. Busca-se também uma forma de reconstruir a sobrecarga a que o músculo é submetido durante o exercício isotônico, através do tratamento do sinal eletromiográfico. Para tanto, o exercício isotônico é realizado em baixa velocidade e com pequena sobrecarga, e além disso, utiliza-se o procedimento de normalizar o sinal eletromiográfico ponto-a-ponto. Tal procedimento não possibilitou que a força externa, aplicada pelo membro, fosse obtida a partir do tratamento do sinal eletromiográfico, porém permitiu a correlação da eletromiografia com a força interna, gerada pelo músculo. Verificou-se também que a relação entre eletromiografia e força varia com a posição angular, com a força, com a velocidade de contração muscular e com a velocidade angular. No que se refere às análises da atividade isotônica, uma importante conclusão é que a relação entre eletromiografia e força não é linear; no entanto, quando normalizados pelos seus valores máximos podem ser considerados proporcionais. / The relationship between electromyography and force is largely investigated, however, such relation is not yet fully understood, still requiring better foundation. One of the reasons that might cause discrepancies between studies lies on directly calculating a single muscle force. Our approach handles the electromyographic signal coupled with a biomechanical model of the joint for assessment of internal muscle forces. This study aims at an evaluation of electromyographic behavior of the quadriceps muscle throughout isometric and concentric exercises, relating it to muscle force calculated by means of simulations, using biomechanical models. It is also handled in our study a means of assessing muscle overloading throughout dynamic exercises using eletromiographic signals. Accordingly, the dynamic exercise is undergone at slow speed and low resistance; and the electromyographic signal is normalized angle by angle. The approach did not allow the external force, produced by the limb, be assessed by means of electromyographic treatment, however, it allowed a relation between electromyography with internal force produced by the limb. It is worth mentioning that the electromyography-force relationship undergoes variations according to angular position, to degree of force, to muscle contraction velocity, to angular velocity. As to isotonic activity analysis, one important conclusion is the relation between electromyography and force is non-linear, with the proviso, that when normalized by peak values electromyography and force may be considered proportional.

Bakgrund: Inom forskningen studeras styrkeförhållandet i lårets muskler och anges ofta som flexor/extensor kvot (F/E-kvot). Ett sätt att mäta denna kvot är att använda isokinetiska styrketest.  Forskningen är inte överens om ett optimalt styrkeförhållande i denna muskulatur eller om för stor styrkeskillnad kan ge upphov till skada. Om en optimal kvot kan fastställas är det intressant i ett förebyggande och rehabiliterande syfte.  Syfte: Att beskriva och jämföra F/E-kvoten hos en grupp manliga fotbollsspelare med en grupp fysiskt aktiva män mellan 16 och 25 år. Metod: Mätning av maximal isokinetisk styrka i knäledens flexor och extensormuskler genomfördes med Genesis Single. Resultat: Studien fann en F/E-kvot hos fotbollsspelarna på 78,2 % på höger ben och 77 % på vänster ben. Jämförelsegruppen hade en F/E-kvot på 73,7 % på höger ben och76,4 % på vänster ben. Utifrån detta kunde man inte finna någon signifikant skillnad mellan de båda grupperna Slutsats: Studien fann ingen signifikant skillnad i F/E-kvot i höger respektive vänster ben mellan en grupp fotbollsspelare och jämförelsegrupp. Vidare forskning om reliabilitet och validitet med Genesis Single som mätinstrument bör utföras innan fler studier utförs med maskinen. / Background: The kneeflexor and kneextensor muscle strength ratio (F/E ratio) is a widely researched area where isokinetic tests are often used. There seems to be little consensus regarding the optimal ratio and also whether a low ratio increase the risk of injury. It would be interesting from a preventive and rehabilitative stand point if an optimal ratio could be decided upon.  Objectives: To compare the F/E ratio between a group of 16-25 year old soccer players and a group of physically active males. Methods: Isokinetic maximal strength in kneeflexors and kneextensors were measured with Genesis Single. Results: The ratio of the soccer players was 78,2 % in the right leg and 77 % in the left. The comparison group was found to have a ratio of 73,7 % in the right leg and 76,4 % in the left leg. There were no significant differences between the two groups. Conclusions: No significant differences could be determined between the two groups. Genesis Single needs to be further investigated with regards to its reliability and validity.

Sammanfattning Bakgrund: Patellofemoralt smärtsyndrom (PFSS) är ett vanligt förekommande muskuloskeletalt besvär bland kvinnor och karaktäriseras av smärta runt eller bakom patella, som förvärras vid vissa viktbärande aktiviteter. Då prevalens är hög hos kvinnor är det av stor betydelse att de får en välanpassad behandling baserad på den senaste tillgängliga evidensen. Syfte:  Att genom en litteraturstudie undersöka effekten av styrketräning på utfallsmåtten smärta och funktion hos kvinnor med PFSS samt gradera den aktuella evidensen. Metod: Litteratursökning utfördes i databasen PubMed. Nio artiklar inkluderades. Artiklarna granskades sedan enskilt enligt TESTEX scale och därefter bedömdes evidensgraden enligt SBU:s GRADE. Resultat: Studien visade en begränsad evidensgrad för att styrketräning av höftmuskulatur minskar smärta. Det finns även en begränsad evidensgrad för att kombinerad styrketräning av höft- och knämuskulatur minskar smärta och ökar funktion. Styrketräning av höftmuskulatur jämfört med styrketräning av endast knämuskulatur har ej effekt på funktion, men evidensgraden bedöms som begränsad. Studiekvaliteten av de enskilda studierna varierade mellan 7–13 poäng vid granskning med TESTEX scale. Konklusion: Evidensen talar för att kombinerad styrketräning av höft- och knämuskulatur bör användas i första hand vid behandling av PFSS, men fler studier behövs för att bekräfta studieresultatet.  Nyckelord: Exercise, hip musculature, patellofemoral pain syndrome, quadriceps musculature / Abstract Background: Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition among women and is characterized by pain around or behind the patella, which is aggravated by weightbearing activities. Since the prevalence among women is high, it is of great importance that they receive a well-adjusted treatment based on the latest available evidence. Objective: To investigate through a literature study the effect of strength training on the outcome measures pain and function among women with PFPS Method: The litterature search was conducted in the database PubMed. Nine papers were included. The papers were evaluated by each author using the TESTEX scale and then the level of evidence was assessed according to SBU’s GRADE. Results: There is limited evidence that strength training of the hip musculature reduces pain. There is also limited evidence that combined strength training of the hip and knee musculature reduces pain and increases function. Compared to strength training of the knee musculature, isolated strength training of the hip musculature is no better to increase function but the evidence is limited. The study quality of the included papers varied between 7–13 points after evaluation with TESTEX scale. Conclusion: The evidence suggests that combined strength training of the hip and knee musculature should be used as the first line of treatment when treating PFPS, but further research is warranted. Key words: Exercise, hip musculature, patellofemoral pain syndrome, quadriceps musculature

Background:People who have survived a stroke often have post-stroke complications. One common complication is muscle weakness in the lower extremities. To treat this, patients can use an ankle-foot orthosis (AFO). The purpose of this study was to investigate muscle morphology in the quadriceps when walking with an AFO. Method:This feasibility cross over study was made on 7 healthy adults. To measure the morphology, an SMG device was used. The device measured muscle area change, EMG -and MMG activation, knee angle and plantar forces. Statistical analyzes was made for all measured data except knee angle.  Result:The area of the quadriceps was significantly smaller when walking with the AFO in mid-swing phase than without (p=0,035). A significant reduction in force could also be found under the MTP1 (p=0,016) and under the calcaneus (p=0,042) in toe off (60%). The result did not show any significant differences in initial contact (p=0,617), mid stance (p=0,287), toe off (p=0,527) or terminal swing (p=0,712) for muscle area change of quadriceps, or plantar force at MTP5 in toe off (p=0,704). Conclusion:The results suggest that the subjects needed to work more with the quadriceps muscles when walking with the AFO. More studies are needed to reach clinical relevance. / Bakgrund:Personer som har genomgått en stroke lider ofta av diverse komplikationer. En vanlig komplikation är muskelsvaghet i den nedre extremiteten. Ett vanligt hjälpmedel för personer med dessa problem är en ankel-fot-ortos (AFO). Denna studies syfte var att undersöka muskelmorfologi (areaförändringar) i quadriceps muskeln när man går med en AFO jämfört med att gå utan.  Metod:Denna förstudie är en korsstudie som utfördes på 7 friska unga vuxna. Ett SMG-system användes på quadriceps för att mäta muskelarean. Enheten mätte muskelarea förändringar, EMG –och MMG aktivering, knävinkel samt plantara krafter. Statistiska analyser genomfördes på all insamlade data förutom knävinkeln.  Resultat:Arean för quadriceps var signifikant mindre när deltagarna gick med AFO i mid swing jämfört med utan (p=0,035). En signifikant skillnad visade sig i den plantara kraften under MTP1 (p=0,016) och under hälen (p=0,042) i toe off (60%).  Resultatet visade inga signifikanta skillnader i initial contact (p=0,617), mid stance (p=0,287), toe off (p=0,527) eller i terminal swing (p=0,712) för quadriceps, eller plantara krafter på MTP5 under toe off (p=0,704). Slutsats:Resultaten pekar på att deltagarna behöver använda sin quadriceps mer i mid swing när de går med en AFO. Fler studier på området behöver göras för att uppnå klinisk relevans.

Introduction: Loaded barbell squat is one of the most popular exercises among athletes and can be performed in many different ways to achieve different goals. The difference in muscle activation between a free and afixed vertical movement path (using Smith machine) has not been examined to a particularly large extent. Aim: To investigate differences in muscle activation of the gluteal and thigh muscles when performing the loaded barbell squat in a free movement path compared to a fixed vertical movement path in healthy athletes under standardized conditions. Methods: Repeated measures within-subjects design were used. Five squats  per condition was performed with a weight representing 100% of the participants bodyweight at a tempo of four seconds per repetition. Muscle activation was measured with the EMG-shorts MBody3. Both conditions tested on the same day and the participants was randomized to what condition to start with. Results: No difference was observed between the conditions for the mean value of muscle activation the whole squat. Mm. quadriceps and mm. hamstrings showed significantly higher muscle activation at the end of the eccentric and the beginning of the concentric phase of the squat when the squat is performed with the barbell in a free movement path. For m. gluteus maximus no difference was observed, neither in the whole squat nor in any parts of the squat. Conclusion: This study provides preliminary evidence that mm. quadriceps and mm. hamstrings muscle group show lower muscle activation in parts of the squat when performed in a Smith machine. No significant difference was observed considering the whole movement. / Introduktion: Knäböj med skivstång är en av de mest populära övningarna bland idrottare och kan utföras på många olika sätt för att uppnå olika mål. Skillnaden i muskelaktivering mellan fri och fixerad vertikal rörelsebana (med Smithmaskin) har inte undersökts i särskilt stor omfattning. Syfte: Att undersöka skillnader i muskelaktivering av sätes- och lårmuskler vid utförande av knäböj med skivstång i en fri jämfört med en fixerad vertikal rörelsebana hos friska idrottare under standardiserade förhållanden. Metod: Upprepade mätningar inom individer användes. Fem repetitioner knäböj per betingelse utfördes på en vikt som motsvarade 100% av deltagarnas egna kroppsvikt. Varje repetition genomfördes på fyra sekunder. Muskelaktivitet mättes med EMG-byxorna MBody3. Båda betingelserna testades under samma dag och deltagarna randomiserades till vilken förutsättning de skulle börja med. Resultat: Ingen skillnad observerades mellan betingelserna för medelvärdet av muskelaktiveringen under hela knäböjen. Mm. quadriceps och mm. hamstrings hade signifikant högre muskelaktivering i slutet av den excentriska och början av den koncentriska fasen av knäböjen då den utfördes i en fri rörelsebana. Ingen skillnad observerades, varken i hela eller delar av knäböjen, avseende m. gluteus maximus. Slutsats: Denna studie ger preliminära bevis på att muskelgrupperna mm. quadriceps och mm. hamstrings uppvisar lägre muskelaktivering i delar av knäböjen när den utförs i en Smithmaskin. Ingen signifikant skillnad observerades i muskelaktiveringen avseende hela rörelsen.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Typical rehabilitation strategies and performance tests after knee surgery are often based on peak lower extremity strength. However, people rarely generate maximal knee force in both daily and sports activities, which are characterized by brief periods of rapid muscle activation and relaxation. Thus, the ability to rapidly develop or modulate force may be more meaningful and more relevant to function. It is unclear how knee surgery influences the neuromuscular mechanisms controlling the ability to rapidly develop leg muscle force and produce power, or the functional relevance of these characterizations of muscle performance in relation to injury, surgery, and recovery. The primary purpose of this collection of studies was to assess rapid quadriceps muscle activation and lower extremity force production in people undergoing arthroscopic knee surgery for meniscal debridement and anterior cruciate ligament (ACL) reconstruction. People undergoing arthroscopic partial meniscectomy (APM) presented with significant deficits in knee extensor rate of torque development (RTD), leg press power, and rapid quadriceps muscle activation both prior to and in the initial month following surgery. Subjective knee function was significantly correlated with RTD variables but not with peak strength or quadriceps volume. Limitations in the ability to rapidly activate the involved quadriceps suggests that impaired centrally mediated neural function of the involved quadriceps may limit RTD and lower extremity power post-surgery. Next, the speed and intensity of quadriceps exercise performed in the early post-surgical period of patients post-APM and the relationships between training parameters, strength, quadriceps RTD, and subjective knee function were investigated. Subjects performed high intensity quadriceps contractions 2-3x/week in the first month following surgery. All subjects increased quadriceps strength, but people who trained with greater RTD following APM demonstrated greater improvements in RTD and had better patient-based outcomes scores than those who trained with a slower rate of torque rise. Finally, power and rate of force development (RFD) in people ≤ 1 year following ACL reconstruction were evaluated along with movement biomechanics, typical clinical measures of readiness to return to activity, and patient-based outcomes. Significant side-to-side asymmetries in quadriceps strength, RFD, leg press strength and power, and knee joint kinetics were noted. Deficits in voluntary quadriceps strength paralleled the deficits in early phase RFD, indicating that in this population RFD was limited by the intrinsic properties and force production capacity of the quadriceps, not the ability to rapidly activate the muscle. However, strong to very strong correlations were found between quadriceps RFD, movement biomechanics and subjective knee function, which were predominantly stronger than the correlations with peak quadriceps strength. Leg press strength, power, and acceleration were very strongly correlated with movement biomechanics and subjective knee function. In summary, this series of studies provides important insight into the neuromuscular mechanisms related to rapid lower extremity force development and muscle activation in the context of knee joint injury and recovery after arthroscopic knee surgery. Collectively, this work suggests that the inability to quickly develop or modulate quadriceps force may have significant functional consequences, and that rehabilitation efforts following arthroscopic knee surgery to incorporate both specific dosage of and earlier performance of rapid leg muscle contractions should be explored.