No description available.

Similar to quadrupedal animals, there is evidence in humans of interlimb signalling during upper and lower limb muscular activation. A product of these interconnections is modulation of motor output via remote neural input. Such remote communication can take several forms; for example, movement modifies activity between upper and lower limbs (e.g. arms to legs) and between a limb pair (e.g. one leg to the other). A specific form of modulation between homologous muscles bilaterally (i.e. the corresponding motor unit pool across the spinal cord) is also seen with strength training. However, details of these motor connections are not well known. Improved understanding of remote influences on motor output and coordination patterns may be valuable in an applied motor re-training setting. Abnormal excitability within reflex pathways of lower limb musculature is common among various neurological disorders. Thus, it is of interest whether remote inputs could be exploited to help normalize dysfunctional motor output. The primary goal of this thesis was to better our understanding of neural interlimb connections; specifically, to examine modulatory responses within the ankle flexor and extensor muscles induced by remote muscular activation associated with both rhythmic arm movement and contralateral resistance training. Further, the final objective of this work was to apply these earlier observations in the context of a post-stroke rehabilitation paradigm, aimed at normalizing muscle activation patterns within the more-affected limb. Initially, this thesis examined spinal reflex excitability within functional antagonists of the lower leg, the ankle flexors and extensor muscles, and the impact of transient, rhythmic movement on these neural networks. Hoffmann (H-) reflexes were first used as a measurement probe. Rhythmic arm cycling significantly suppressed reflex amplitude in extensors, but revealed a bidirectional (i.e. either suppression or facilitation) reflex modulation in flexor muscles. Thus, differential regulation of ankle flexor and extensor H-reflex amplitudes was evidenced during rhythmic arm movement. This may stem from differences in locomotor pattern generator output to these groups as well as increased involvement of cortical drive to the flexors relative to the extensors during rhythmic movement. These results support the presence of interlimb neural coupling, such that remote motor action (arm movement) influences lumbar spinal cord excitability. Additionally, these descending signals impact ankle flexors and extensors differentially, which illustrates a method of producing facilitative modulation of ankle flexor motor responses. Second, reciprocal inhibition (RI) was used to examine regulation of excitability between these same lower limb functional antagonists during rhythmic arm movement. Arm cycling significantly increased RI in ankle extensors, but had no effect in the flexors. This extends observation of remote motor activity-induced modulation on spinal excitability to the core circuitry that comprises the interaction between functional agonist/antagonist pairs. Moreover, the asymmetry of this effect highlights differences in descending supraspinal inputs to ankle flexors vs. extensors, and may be related to functional dorsiflexion requirements during locomotion. Subsequently, this thesis explored long term plasticity of interlimb neural modulation resulting from remote motor activation in the form of resistance training. Specifically, the within limb pair ‘cross-education’ phenomenon was investigated via unilateral isometric strength training of the ankle flexors. The first of these training interventions was implemented in a cohort of neurologically intact subjects who performed five weeks of one-sided maximal isometric dorsiflexion training. H-reflex recruitment curves were used to probe for training-induced spinal plasticity within the agonist (flexor) and antagonist (extensor) muscles bilaterally. Post-intervention, dorsiflexor torque significantly increased in the trained and untrained limbs. Further, significant changes in H-reflex excitability were detected in the trained flexor (agonist) muscle and in both extensor (antagonist) muscles. These findings reveal that muscular crossed effects can be obtained in the ankle dorsiflexor muscles, and provide novel information on agonist and antagonist spinal adaptations that accompany unilateral training. They also suggest potential for application of remote motor activation (resistance training) to induce interlimb neural plasticity within a clinical context, such as improving one-sided weakness and/or motor dysfunction following neurotrauma. The final training intervention was implemented in a chronic (>6mo post-infarct) stroke clinical group who completed six weeks of maximal isometric dorsiflexion training in the less-affected leg. Voluntary isometric strength (dorsiflexion torque, muscle activation), reciprocal inhibition (RI), walking ability and clinical function were used to quantify training effects. Post-intervention, dorsiflexion torque and maximal flexor muscle activation significantly increased in both the more-affected (untrained) and less-affected (trained) legs. Further, the relation between size of RI and level of muscle activation in the more-affected flexor muscle was significantly altered by training, and the Timed Up and Go clinical test was significantly improved. Thus, significant gains in voluntary strength, muscle activation and spinal excitability on the untrained, more-affected side after stroke can be invoked through training the opposite limb. This translates into small but observable functional improvements. Taken together, the data in this thesis provide a basis for novel motor re-training approaches. Improved understanding has been gained of the similarities and differences between remote motor influences received by ankle flexor and extensor muscles in the lower leg. These observations culminate in the implementation of a novel post-stroke training paradigm, which shows that remote muscle activation, i.e. the cross-education effect, can induce strength and functional gains in the more-affected limb. / Graduate

No description available.

Title: Phylogenetical consequenses of human locomotion realizated during the schoulder girdle Objectives: Description of phylogenetic context of human locomotion realized through the shoulder girdle Methods: Study and analysis of the available literature Analytic-synthetic comparison of the current knowledge of evolution Study of available sources of phylogeny of locomotion in terrestrial vertebrates Results: It was found similarity in the basic control of human bipedal locomotion to control of quadrupedal locomotion of other animals and similarity in the specific form of human locomotion to locomotion of non-human primates Keywords: Bipedal locomotion, quadrupedal locomotion, control of locomotion, interlimb coordination

This dissertation presents three experiments to investigate the general distribution of hand preference across a reachable working space, as well as the effect of sensory information about the reaching hand, and if this distribution is affected by long term practice. In addition, the underlying mechanisms of hand preference behavior were investigated with the obtained kinematic data. Experiment 1 explored the distribution of hand preferences across the workspace among non-athlete right-handed participants, as well as the role that visual feedback might play in this distribution. Experiment 2 tested the hypothesis, if occlusion of visual feedback influences hand preference, accordingly interlimb differences. The third final experiment examined the effect of long term practice on hand preference among right-handed elite fencers. The first study showed that the choice of arms is related to the energetic cost and dynamic efficiency of the movements. The results of the second experiment displayed that the choice of hands changes under no visual feedback condition, demonstrating that the choice is active and not habitual, depending on sensorimotor performance asymmetries. The final experiment demonstrated that elite athletes have different patterns of limb selection than non- athletes. Athletes, specifically fencers, show improved coordination in their non-dominant arms, which apparently increases the selection of this arm for reaching. Overall, it was concluded that hand preference depends on sensorimotor performance asymmetries and influenced by the long term practice.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18946号 / 工博第3988号 / 新制||工||1614 / 31897 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 泉田 啓, 教授 藤本 健治, 教授 松野 文俊 / 学位規則第4条第1項該当

La coordination des membres est un élément essentiel pour la marche terrestre chez les mammifères. Les mécanismes neuronaux et biomécaniques s'ajustent pour assurer le maintien d'un équilibre dynamique dans un environnement changeant. Lorsque le système est confronté à une perturbation persistante, la coordination des membres s'adapte. L'adaptation est définie comme un recalibrage du mouvement en réponse à une perturbation persistante ainsi que la présence d'après-effets une fois la perturbation disparue, ce qui indique que le nouveau patron a été entreposé dans le système nerveux central. Chez l'homme, le patron locomoteur s'adapte à une marche prolongée sur un tapis roulant partitionné, où l’une des jambes marche à une vitesse supérieure à l'autre, en rétablissant progressivement la symétrie des variables inter-jambes: périodes de double support et des longueurs des pas, ainsi qu’en réduisant l'amplitude de l'activité musculaire (EMG, électromyographie). L’objectif de notre étude était de déterminer si des chats intacts et des chats ayant subis une lésion complète de la moelle épinière (chat spinalisé) s’adaptent à la marche partitionnée prolongée. Pour caractériser l’adaptation locomotrice chez le chat intact et spinalisé, une prise de données cinématiques et électromyographiques des membres postérieurs a été effectuée chats intacts et les chats spinalisés, les longueurs de pas et les périodes de doubles supports étaient, en moyenne, symétriques, pendant la locomotion sur tapis roulant non-partitionné, et sont devenus asymétriques lors de la locomotion sur tapis roulant partitionné. Ces mesures inter-jambes sont demeurées asymétriques tout au long de la période de marche sur tapis roulant partitionné. Au retour à la marche sur tapis roulant non-partitionné, la symétrie a été immédiatement restaurée sans la présence d’après-effets. Chez les chats intacts, l'amplitude EMG moyenne des extenseurs a augmenté pendant la locomotion sur tapis roulant partitionné et elle est restée augmentée tout au long de cette période, alors que chez les chats spinalisés, l'amplitude EMG des membres postérieurs n'a pas changé. Ces résultats indiquent qu’il n’y a pas d’adaptation locomotrice chez le chat intact et spinalisé, ce qui suggère une importante différence physiologique dans le contrôle de la locomotion entre les chats et les humains lors d’une marche asymétrique prolongée. Par conséquent, nous proposons que la symétrie gauchedroite ne s’avère pas importante pour maintenir un équilibre dynamique pendant la locomotion asymétrique prolongée chez le chat, un quadrupède, comparé à l’humain adulte, un bipède. / Abstract : Coordination of the limbs is an essential component of terrestrial locomotion in mammals. When the system is confronted with persistent perturbations from the environment, the interlimb pattern learns to adapt. Adaptation is defined as a recalibration of the movement in response to a persistent perturbation as well as the presence of after-effects upon removal of the perturbation, indicating storage of the new pattern within the central nervous system. In humans, the pattern adapts to prolonged locomotion on a split-belt treadmill, where one leg steps faster than the other, by gradually restoring the symmetry of interlimb variables (double support periods, step lengths) and by reducing the amplitude of muscle activity (EMG, electromyography). The adaptation is also characterized by a reversal of the asymmetry of interlimb kinematic variables initially observed during the early split-belt period when returning to tied-belt locomotion (i.e. an after-effect). To assess the presence of locomotor adaptation, we measured intralimb (stance durations) and interlimb (double support periods, step lengths) variables bilaterally as well as EMG in the hindlimbs of intact and spinal-transected cats before, during and after 10 mins of split-belt locomotion. In both intact and spinal cats, step lengths and double support periods were, on average, symmetric, during tied-belt locomotion, and became asymmetric during split-belt locomotion. These interlimb variables remained asymmetrical throughout the split-belt period and upon returning to the tied-belt condition, left-right symmetry was immediately restored. In intact cats, the mean EMG amplitude of extensors increased during split-belt locomotion and remained increased throughout the split-belt period, while in spinal cats, hindlimb EMG amplitude did not change. The results indicate a lack of adaptation during prolonged split-belt locomotion in intact and spinal cats, suggesting an important physiological difference in the control of locomotion between cats and humans during prolonged asymmetric stepping. We propose that restoring left-right symmetry is not important to maintain dynamic balance during prolonged asymmetrical locomotion in the cat, a quadruped, as opposed to the adult human, a biped.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18946号 / 工博第3988号 / 新制||工||1614(附属図書館) / 31897 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 泉田 啓, 教授 藤本 健治, 教授 松野 文俊 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Background: Balance is important for performing activities and sports in daily life. Although it is widely accepted, that warming up can increase readiness for exercise, the effect of warming up on balance is unclear as results vary between studies. As warm-up can potentially affect the Star Excursion Balance Test (SEBT) results and physiotherapists use tests to evaluate the effects of interventions, it is important to perform tests in a standardised way. Aim: To investigate the effect of warm-up on dynamic control among injury-free 20–30 year old individuals. Design: Randomised cross-over study. Method: 18 participants performed test A and B, where test A included a warm-up programme and SEBT, and B included only SEBT. The test each participant started with was randomised. Normalised and composite SEBT scores were used to analyse the data. Result: There was no statistically significant difference in SEBT scores for either the dominant or non-dominant leg when compared with and without warm-up. When analysing the difference in mean (SEBT composite %) between with and without warm-up for dominant versus non-dominant legs, a small but significant difference was seen, in the form of a positive effect of warm-up for the non-dominant leg. Conclusion: The results showed that warm-up had no statistically significant effect on either the dominant or non-dominant leg. The difference between the effect of warm-up on the dominant and non-dominant leg was statistically significant as the non-dominant leg was not affected in the same way. Further research is needed to confirm these results. / Bakgrund: Balans är viktigt för att kunna genomföra aktiviteter och idrott i det dagliga livet. Även om det är allmänt accepterat att uppvärmning kan öka beredskap för träningen, är effekten av uppvärmning på balansen oklar då resultaten varierar mellan olika studier. Då uppvärmning kan potentiellt påverka testresultatet vad gäller Star Excursion Balance Test (SEBT) och fysioterapeuter använder tester för att kunna utvärdera effekter av interventioner, är det viktigt att utföra tester på ett standardiserande sätt. Syfte: Att undersöka vilken effekt uppvärmning har på dynamisk kontroll hos skadefria 20–30 år gamla individer. Design: Randomiserad cross-overstudie. Metod: 18 deltagare utförde test A och B, där test A inkluderade ett uppvärmningsprogram och SEBT, och B inkluderade bara SEBT. Testet varje deltagare började med slumpades ut. Normaliserade och sammansatta SEBT-poäng användes för att analysera data.   Resultat: Det förelåg ingen statistiskt signifikant skillnad i SEBT-poäng för vare sig det dominanta eller icke-dominanta benet vid jämförelse med respektive utan uppvärmning. Vid analys av skillnad i medelvärde (SEBT sammansatt %) mellan uppvärmning och inte för dominanta jämfört med icke-dominanta ben sågs en liten, men signifikant skillnad, i form av positiv effekt på uppvärmning för det icke-dominanta benet.  Konklusion: Resultaten visade att uppvärmning inte hade någon statistiskt säkerställd effekt på varken det dominanta och icke-dominanta benet. Skillnaden mellan hur uppvärmningen påverkat det dominanta och icke-dominanta benet var statistiskt signifikant då det ickedominanta benet påverkades inte på samma sätt. Ytterligare forskning behövs för att bekräfta dessa resultat.