The event related potential (ERP) technique is enjoying widespread application in neurophysiological research due to its fine temporal resolution. Of relevance to this study are ERPs related to voluntary movements. The precision with which movement related processes could be recorded using the ERP technique was demonstrated by Gilden, Vaughan and Costa (1966) and Kutas and Donchin (1974, 1977, and 1980) who found that the readiness potential (RP) immediately preceding hand movement was larger over the hemisphere contralateral to the responding hand. Given that left hemisphere controls right hand movements and vice versa, their findings confirmed that the lateralized readiness potential (LRP) is an index of motor preparation. It has been well established that electrodes from the left precentral site (C3) and from the right precentral site (C4) can capture LRPs, and that the motor cortex is the major generator of this component. In the speech domain, researchers recording ERPs related to motor preparation have often considered pre-determined electrode sites (e.g., F3, F4, C3, C4, Cz) assuming that their proximity to motor areas on the cortex enables capturing of specific activity from those areas [F3 close to Broca’s area, Cz close to Supplementary motor area (SMA), C3 to left motor strip, C4 to right motor strip]. A consistent finding has been that the RP preceding speech is greatest at the central electrode sites, which has been attributed to SMA and motor cortex activity. Studying speech production related ERPs at predetermined set of electrodes might not suffice for two reasons: (1) unlike simple finger movement, speaking is a fine motor skill requiring coordination of multiple systems (e.g., respiratory system, phonatory system, articulatory system) and muscles, and (2) the far-field nature of the ERP recording technique often results in spatial and temporal overlap of components. To overcome these challenges, this study considered multichannel recordings and principal component analysis (PCA). Twenty three healthy participants completed a simple hand motor task (pressing a button with the right index finger and another button using the left index finger based on the color of a stimulus frame displayed on a computer screen), and a speech task (saying “pool” or withholding the response based on the color of the frame). The purpose of including a hand motor task was to verify that neural activity specific to motor preparation was detectable in participants when a well-established condition for the elicitation of LRPs was utilized. Both stimulus-locked and response-locked ERPs from 21 right handed participants (11 females and 10 males) were studied. Interhemispheric difference wave analysis and PCA revealed left hemisphere lateralization of the potential (i.e., the LRP) immediately preceding right hand movements, similar to previous studies. The LRP specific to left hand movements (non-dominant hand), however, showed bihemispheric distribution. Results from the speech motor task confirmed that overlapping components affect interpretation of ERPs related to speech production if just central electrode sites are considered. Two ERP components emerged from the multichannel PCA as distinguishing between the speaking and no speaking condition: a posterior negative component and a left lateralized positive component. The morphology of the posterior negative component and significant moderate correlation of its amplitude with the mean reaction time suggest that this component is a possible index of speech motor preparation. Further research is required to determine whether the left-lateralized component reflects a process mediated by the speech dominant hemisphere (left). In addition to demonstrating the usefulness of multichannel recordings and PCA in ERP investigations, the study provides several methodological guidelines for capturing ERPs related to speech production.

O objetivo principal deste estudo foi investigar o efeito da posição de coordenação, proposta no método da coordenação motora de Piret e Béziers (1992), na resposta de torque em preensão digital. Dezesseis jovens adultos (24,7 ± 2,2 anos de idade) foram solicitados a realizar duas tarefas distintas: produção de torque máximo em preensão digital e controle de torque em preensão digital constante e contínuo. Ambas as tarefas foram avaliadas em quatro diferentes posições do cotovelo (posição livre, em extensão, 45º de flexão e 90º de flexão) e três níveis relativos distintos de torque máximo (20%, 40% e 60%). Pique do torque máximo, variabilidade, irregularidade e precisão da resposta motora foram utilizados como variáveis dependentes. Os resultados não revelaram efeito da posição do cotovelo na produção de torque em preensão digital máximo e nem na resposta de controle de torque em preensão digital. Todavia, a resposta de controle de torque mostrou-se mais variável, mais irregular e menos precisa com o incremento dos níveis relativos de torque máximo. Tais achados não oferecem suporte à premissa do método da coordenação motora, o qual preconiza a existência de uma posição articular ótima do membro superior para a coordenação e controle motor. Além disso, os resultados permitem a constatação de que maiores níveis de torque demandam ajustes neuromotores mais complexos no sistema sensório-motor, todavia a posição do cotovelo parece não caracterizar-se como uma restrição determinante da tarefa de torque em preensão digital. / The main aim of this study was to investigate the effect of the coordination position, proposed by the coordination method (Piret & Bézier, 1992), on the thumb-index torque production. Sixteen young adults (24,7 ± 2,2 years old) were asked to perform two different tasks: Maximum thumb-index torque production and constant thumb-index torque. Both tasks were evaluated in four different elbow positions (free position, extension, 45º of flexion and 90º of flexion) and three relative levels of maximum thumb-index torque production (20%, 40% & 60%). Maximum peak torque, variability, irregularity and accuracy were used as dependent variables. The results showed neither effects of the elbow position on the maximum thumb-index torque production nor in the constant thumb-index torque task. However, the constant thumb-index torque responses were more variable, more irregular and less accurate with increased relative levels of the thumb-index torque production. These findings do not support the coordination method premise that we have an optimum upper-limb position which provides a better coordination and motor control. Furthermore, the results allow the interpretation that larger level of the thumb-index torque production demands more complex neuromuscular adjustments of the motor-sensory system; however, the elbow position does not appear to be a determinant constraint during a thumb-index torque task.

Assimetrias de desempenho, frequentemente, são relacionadas ao controle e desenvolvimento motor da extremidade superior. Por outro lado, a extremidade inferior do corpo humano está muito mais envolvida em ações bilaterais, como aquelas relacionadas à locomoção. Ainda assim, diferenças no desempenho dos membros inferiores foram descritos na literatura, como, por exemplo, em relação à força durante tarefas de andar, correr e pedalar. As razões para essas diferenças - uma vez que ambos os membros inferiores, teoricamente, tem a mesma possibilidade de movimento e a preferência lateral pode mudar de acordo com a tarefa - tem intrigado cientistas. Em estudos prévios apresentados na literatura, notamos que assimetrias na força produzida ocorrem durante a pedalada, apresentando relação, por exemplo, com a intensidade do exercício. Também sugere-se que a experiência com a tarefa influencie assimetrias. Entre os motivos para estudar esses mecanismos de assimetria está o risco aumentado de lesão inerente a assimetrias cinéticas, como constatado na corrida, assim como a importância de empregar estratégias unilaterais de treinamento e/ou reabilitação. A ativação muscular foi sugerida como sendo um fator determinante de assimetrias. A ativação muscular nos membros inferiores poderia diferir entre os membros, e tal como ocorre para a extremidade superior, levar a vantagem em favor da perna preferida. No entanto, essa hipótese não havia sido testada, considerando exercícios em diferentes configurações e sujeitos com diferentes níveis de experiência. Assim, buscamos investigar as diferenças entre o membro inferior preferido e não-preferido durante a pedalada, em testes bilaterais e unilaterais, considerando: (1) o consumo de oxigênio, (2) a eficiência muscular, (3) a magnitude da ativação muscular, (4) a variabilidade na ativação muscular, e (5) a comunicação entre os membros durante ações isoladas de um dos membros inferiores. Protocolos de ciclismo (a) incremental máximo, (b) submáximo de carga constante para pedalada bilateral, e (c) submáximo de carga constante para pedalada unilateral, com o membro inferior preferido e não-preferido, foram realizados por ciclistas e não-ciclistas. As análises estatísticas sugeriram que durante a pedalada bilateral, assimetrias de força previamente descritas não parecem estar relacionadas com diferenças na magnitude de ativação muscular (biceps femoris, gastrocnemius medialis e vastus lateralis) entre o membro inferior preferido e nãopreferido. No entanto, a variabilidade da ativação foi influenciada pela preferência em não-ciclistas. No exercício unilateral, a preferência lateral não influenciou o consumo de oxigênio e a eficiência muscular. A magnitude da ativação muscular e a sua variabilidade também não diferiram estatisticamente entre as pernas durante os protocolos unilaterais, o que não ajuda a explicar assimetrias de força dependentes em aspectos neurais. Os resultados de comunicação entre membros sugerem efeitos da preferência lateral para ciclistas na perna preferida, o que poderia influenciar a transferência interlateral de aprendizagem em sujeitos treinados. Dessa forma, a preferência lateral parece não influenciar a magnitude da ativação muscular e eficiência muscular, no entanto, ela pode apresentar diferentes efeitos frente à variabilidade da ativação muscular e da comunicação entre os membros em função da experiência com ciclismo. Assimetrias encontradas no ciclismo parecem mais frequentes para a força e podem ser relacionadas à configuração da atividade e ao efeito do ambiente de prática, sem apresentar correlatos com a ativação muscular. / Performance asymmetries are frequently addressed by studies on motor control. Research projects adopt protocols which will assess unimanual and bimanual action in order to determine lateralization and transfer of learning processes, as well as to monitor the development of learning. On the other hand, the lower limbs of the human body are more related to bilateral actions, such as those required for locomotion. Nevertheless, differences in the performance between lower limbs have been reported in previous investigations for force, during walking, running and cycling. The factors which determine these differences - once both lower limbs in theory have the same possibility to be recruited and the leg preference can switch according to the tasks requirements - have been discussed in the literature. Previous studies from the literature reported force asymmetries during pedaling, which appeared dependent on exercise intensity and experience. Among the motivations to study mechanisms of asymmetry is the increased risk of injury associated with kinetic asymmetries, as previously described for runners, as well the development of unilateral strategies of training and rehabilitation. Muscle activation was suggested as a factor determinant of limb asymmetries. The muscle activation could differ between lower limbs as observed for upper extremity, and lead to advantages in favor of preferred limb during dynamic actions. Although proposed in the literature, this hypothesis was not tested using different configurations of exercise and subjects with different levels of experience with pedaling. Therefore, we investigated differences between preferred and non-preferred limbs during bilateral and unilateral pedaling. Parameters measured included (1) oxygen uptake, (2) muscle efficiency, (3) magnitude of muscle activation (4) variability of muscle activation, and (5) interlimb excitation during isolated actions of one limb. Cycling protocols consisted of (a) incremental maximal cycling test, (b) bilateral pedaling at submaximal intensity, and (c) unilateral pedaling at submaximal intensity, with preferred and non-preferred limbs. Tests were performed by cyclists and non-cyclists. The statistical analysis suggested that during bilateral pedaling, force asymmetries described in the literature appeared not related to differences in magnitude of muscle activation (biceps femoris, gastrocnemius medial head, and vastus lateralis) between preferred and non-preferred lower limbs. Despite of this, variability of muscle activation was influenced by leg preference in noncyclists. During unilateral pedaling, leg preference did not statistically influence oxygen uptake and muscle efficiency. Magnitude of muscle activation and its variability did not differ statistically between legs. This finding does not support force asymmetry as dependent on neural factors related to the magnitude of muscle activation. The result of interlimb excitation suggests the effects of lateral preference for the preferred leg of cyclists, which could influence the interlimb transfer of learning in trained subjects. In summary, lateral preference appeared not to influence magnitude of lower limbs muscle activation and muscle efficiency, but can present different effects on variability of muscle activation and interlimb communication according to cycling experience. Asymmetries found during cycling appear more frequent for force and can be dependent on the exercise configuration and environment, without correlation with the muscle activation.

O núcleo tegmental rostromedial (RMTg) é uma estrutura relé GABAérgica entre a habênula lateral (LHb) e a área tegmental ventral (VTA), que também recebe projeções diretas da LHb. Para detalhar a topografia das projeções da LHb para o RMTg e VTA, injeções de um traçador anterógrado foram depositadas na LHb. A origem das projeções da LHb para o RMTg e VTA foi confirmada com injeções de um traçador retrógrado, no RMTg ou VTA. Além disso, comparamos a posição topográfica dos neurônios marcados no RMTg após injeções na VTA, com os axônios marcados, vindas da LHb. Nossos dados revelaram que as projeções da LHb estão organizadas de maneira topográfica, com projeções para o RMTg, se originando da LHb lateral e as projeções para a VTA da LHb medial. No RMTg, axônios oriundos da LHb foram observados pertos de neurônios que se projetam para a VTA, formando aposições com esses neurônios. Os resultados indicam que as projeções da LHb para o RMTg e VTA originam-se de diferentes regiões da LHb e provam a existência de uma via bisináptica que conecta a LHb com a VTA via o RMTg. / The rostromedial segmental nucleus (RMTg) is a GABAergic relay between the lateral habenula (LHb) and the ventral tegmental area (VTA), which also receives direct projections from the LHB. To detail the topography of LHb projections to the RMTg and VTA, injections of an anterograde tracer were made into the LHb. The origin of LHb projections to the RMTg and VTA was then confirmed by injections of a retrograde tracer into the RMTg or VTA. Additionally, we compared the topographic position of RMTg neurons labeled from injections in the VTA with that of axons labeled from the LHb. Our data revealed that LHb projections are organized in a topographic manner, with projections to the RMTg emerging from the lateral LHb and those to the VTA arising from the medial LHb. In the RMTg, LHb axons were found in register with VTA projecting neurons and were frequently apposed to the latter. Our findings indicate that LHb inputs to the RMTg and VTA arise from different divisions of the LHb and provide evidence for a disynaptic pathway that links the LHb to the VTA via the RMTg.

Todo ser humano apresenta oscilações posturais aleatórias durante a postura ereta quieta advindas de mecanismos centrais e periféricos. Um toque suave (LT do inglês light touch) de um dos dedos sobre uma superfície fixa ao solo resulta em uma pista sensorial adicional, que promove uma diminuição das oscilações posturais. Entretanto, há necessidade de se obter maiores conhecimentos sobre mecanismos associados ao LT, tanto no que tange a aspectos sensoriais quanto motores associados ao fenômeno. O presente estudo teve como objetivo avançar no entendimento sobre a influência do LT sobre o comportamento de múltiplas variáveis extraídas durante a postura ereta quieta. O primeiro capítulo investigou quantificadores de oscilações posturais com base em medidas como o centro de pressão (CP), centro de massa (CM) e ângulos segmentares e corporais durante experimentos com condições em superfície estável e instável, com olhos abertos e olhos fechados, comparando as condições com e sem LT. Adicionalmente, foi analisada a coerência espectral entre sinais de eletromiograma de diferentes músculos do corpo e os quantificadores acima elencados nas diferentes condições. Os resultados mostraram que o LT diminui o nível de ativação de alguns músculos, principalmente o músculo gastrocnêmico medial, importante na manutenção do controle postural. A variabilidade dos ângulos segmentares e corporais, conjuntamente com variáveis extraídas do CP e do CM diminuíram em condições com LT. Na análise de coerência o LT promoveu algumas alterações nos padrões de oscilação entre ângulos, CP, CM e sinais de eletromiograma, porém com poucas modificações na fase entre os sinais. Na análise de coerência intermuscular, comparando pares de músculos do lado direito e esquerdo do corpo, observou-se que para os membros inferiores a coerência ocorre geralmente na faixa de 0 a 1-2 Hz (em fase), podendo aumentar a faixa de frequência em situações mais instáveis (sem visão e superfície instável), em que o LT passa a influenciar de maneira mais significativa a coerência entre os sinais. O segundo capítulo deste estudo foi motivado por estudos que mostraram ser possível manipular as entradas sensoriais geradas pelo dedo durante o LT. O presente estudo investigou se a retirada de uma entrada sensorial proprioceptiva associada ao dedo é capaz de alterar a oscilação postural, possibilitando a separação e quantificação da contribuição sensorial cutânea da contribuição proprioceptiva dos músculos do terceiro dedo. O controle postural foi avaliado com os sujeitos de olhos fechados e sobre uma superfície instável. Os resultados indicaram que a retirada da informação sensorial proprioceptiva do dedo diminuiu a variabilidade e a velocidade do CP, indicando que a informação cutânea sem a adição de interferências proprioceptivas pode diminuir as oscilações posturais / Human subjects during upright stance show random postural oscillations which are controlled by the central nervous system. A light touch of an index finger (LT) on a surface fixed to the ground results in an additional sensory cue, which promotes a decrease in postural oscillations. However, there is a need to improve the knowledge about mechanisms associated with LT, both with respect to sensory and motor aspects associated with the phenomenon. This study aimed to further the understanding of the influence of LT on the behavior of multiple variables measured during upright stance. The first chapter analyzed variations of some quantifiers of postural sway based on the center of pressure (CP), center of mass (CM) and joint and body angles during experiments with different surface and vision conditions, with and without LT. In addition, the spectral coherence was analyzed between electromyogram signals from different muscles of the body and the previously listed sway quantifiers. The results showed that LT decreases the level of activation of some muscles, particularly the medial gastrocnemius, an important muscle for the maintenance of posture. Segmental and body angle variability and variables extracted from the CP and CM decreased in conditions with LT. In coherence analysis LT promoted some changes in patterns of oscillation between angles, CP, CM and EMGs, but with few modifications in the phase between the signals. The intermuscular coherence analysis (comparing the right and left muscles pairs of the body) showed that significant changes usually occured in the range of 0 to 1-2 Hz (in phase) for the lower limbs and may increase the frequency range in unstable situations (without vision and unstable surface). In these cases LT starts to affect more significantly the coherence between signals. The second chapter of this study was motivated by results from studies that have shown that it is possible to manipulate the sensory inputs generated by the finger during LT. This study investigated whether the withdrawal of a finger proprioceptive input affects postural sway, allowing an analysis of the effects of cutaneous sensory inputs of the third finger muscles. Postural control was evaluated with the subjects with the eyes closed and on an unstable surface. The results showed that removal of proprioceptive information from the finger flexor muscles decreased the variability and speed of the CP, indicating that cutaneous inputs without proprioceptive information may decrease postural sway

O ser humano desenvolve uma série de atividades motoras bilaterais que, aparentemente, deveriam ser simétricas, tais como o salto, o agachamento e o caminhar. Porém, quando um dos membros inferiores sofre um acometimento estrutural, estas tarefas passam a ser realizadas de forma assimétrica. Quando uma assimetria está presente mesmo após um período de reabilitação, devida atenção deve ser tomada, pois, provavelmente, o membro acometido ainda apresenta algum déficit e o membro contralateral está sendo sobrecarregado. Um exemplo disso é a lesão do Ligamento Cruzado Anterior (LCA) que, mesmo após o período total de reabilitação, os sujeitos podem apresentar déficits no membro operado. A pesar da grande quantidade de trabalhos relacionados à lesão e à reconstrução do LCA, poucos analisam a simetria do movimento entre os membros inferiores durante a realização de tarefas bipedais. Sendo assim, o objetivo do presente estudo foi analisar a simetria entre os membros inferiores desses sujeitos, durante a realização das seguintes tarefas: agachamento bipedal com e sem carga e salto bipedal com contramovimento. A amostra foi composta por 34 indivíduos, divididos em dois grupos: 17 sujeitos do grupo LCA (todos submetidos à reconstrução do LCA, tendo como enxerto os tendões flexores e com mais de um ano de cirurgia) e 17 indivíduos do grupo controle (sem qualquer afecção nos membros inferiores). Para coleta dos dados foi utilizado um sistema de análise cinemática 3D, composto por seis câmeras de emissão de sinais infra-vermelhos, além de um sistema de análise cinética, composto por duas plataformas de força. Pôde-se observar que, durante o 6 agachamento sem carga, não foram detectadas assimetrias. Já no agachamento com carga, observou-se que os sujeitos do grupo LCA são mais assimétricos nas variáveis: potência articular do joelho e razão entre os momentos de quadril e joelho. Na realização do salto, além dessas assimetrias, o grupo LCA apresentou déficits nos seu membro operado, em relação ao membro contralateral, nas seguintes variáveis: potência mecânica, potência articular do joelho e razão entre os momentos de quadril e joelho. Os resultados do presente estudo mostram que os sujeitos submetidos à reconstrução do LCA, mesmo após um ano de pós-operatório, e mesmo após o retorno à prática esportiva, ainda apresentam assimetrias entre seus membros inferiores. Sugere-se a revisão dos protocolos de reabilitação, tendo em vista que a presença dessas assimetrias pode predispor esses sujeitos à lesão do membro contralateral, assim como de casos de recidiva. Os protocolos atuais enfatizam a realização de exercícios bipedais em cadeia fechada os quais possibilitam alguns padrões de compensação, enquanto que exercícios unipedais em cadeia aberta isolam mais o grupo muscular a ser exercitado. / Human beings develop various bilateral motor activities that should supposedly be symmetrical, for example; jumping, squatting and walking. However, when one of the lower limb suffers from a structural injury, these tasks are then performed asymmetrically. When asymmetry is present, even after a rehabilitation period special attention must be paid to it, because the injured limb may still present some deficits and the contralateral limb may be overloaded. An example of this is the Anterior Cruciate Ligament (ACL) injury. The patient can present deficits in the operated limb even after the rehabilitation period has been completed. In spite of the vast amount of studies related to ACL injuries and reconstruction, only few of them analyze the symmetry of the movement between the lower limbs during the execution of bipedal tasks. Therefore, the objective of this study was to analyze the symmetry between the lower limbs of these patients, during the accomplishment of the following tasks: bipedal squat with and without load and bipedal jump with countermovement. The analysis was based on 34 people, divided in two groups: 17 patients in ACL group (all admitted for ACL reconstruction, having the flexor tendons as graft and more than a year after the surgery) and 17 people in the control group (without any lesion in the lower limbs). For data collection, a 3D-kinematics analysis system was used, composed of six cameras with an infrared signal emission, also in addition to a kinetic analysis system composed of two force plates. It was possible to observe that asymmetries were not detected during the squat without a load. However, in the squat with a load, it was observed that the ACL group were more asymmetrical in the 8 following variables: knee power and ratio between hip and knee moments. During jumping, beyond these asymmetries, deficits were observed in the operated limbs of the ACL group, in relation to the contralateral limb, in the following variables: mechanical power, knee power and ratio between hip and knee moments. The results of this study show that the patients admitted for ACL reconstruction, even after one year of postoperative treatment and returning to practical sports, still present lower limb asymmetries. It is suggested to review the rehabilitation protocols considering that the presence of these asymmetries can predispose these people to contralateral limb injuries, as well as cases of reinjury. The current protocols emphasize the accomplishment of closed chain bipedal exercises which make some compensations possible, whereas unipedal open chain exercises isolate the muscular group to be exercised.

A presente dissertação é composta por três manuscritos originais. O objetivo do estudo (1) foi comparar o desempenho no chute em jogadores de futebol treinados sub-9 até sub-20. Jovens jogadores brasileiros (N = 366) foram avaliados por cinemática 3-D (300 Hz) a fim de mensurar a velocidade da bola, velocidade do pé, razão velocidade bola/pé, comprimento do último passo e distância entre pé de suporte e bola. Um procedimento 2-D (60 Hz) foi conduzido para calcular a acurácia dos chutes. A velocidade da bola aumentou em 103% do sub-11 (48,54±8,31 km/h) até sub-20 (98,74±16,35 km/h). Em contraste a velocidade do pé exibiu aumento de 59% do sub-11 (49,08±5,16 km/h) até sub-20 (78,24±9,49 km/h). Isso foi em decorrência da melhora na qualidade de impacto pé-bola (razão velocidade da bola/pé: sub-11: 0,99±0,13; sub-20: 1,26±0,11 u.a.) (p < 0,001). Erro médio radial e acurácia parecem prejudicados durante o surto de velocidade do crescimento (sub-13-sub-15). Conclui-se que parâmetros Biomecânicos de desempenho chutando apresentam desenvolvimento diferenciado. O objetivo do estudo (2) foi investigar o desempenho chutando (N = 105 selecionados) no sub-11 até sub-20 com foco em velocidades lineares, deslocamento angular e velocidade angular articular do membro inferior. Verificou-se as possíveis diferenças entre idades, status jogando (titulares, reservas e não relacionados) e a influência da maturidade (iPVC) em parâmetros chutando. Pequenos ganhos em termos de velocidade e poucas alterações angulares ocorreram nos mais jovens (sub-11 até sub-13). Na idade sub-15 ocorrem os maiores aumentos de velocidades e transferência próximo-distal. Esse é um período crítico em que o desempenho chutando discriminou o status de jogo. O iPVC não influenciou o desempenho. Conclui-se que a taxa de desenvolvimento do desempenho chutando difere entre sub-11 até sub-20 em jogadores selecionados. O objetivo do estudo 3 foi examinar o desempenho de corrida (ex. distância total percorrida, faixas de velocidade atingidas), relacionado a habilidades técnicas (ex. envolvimento com bola, passes, toques na bola, toques/posse, duelos e chutes) e dinâmicas de movimentos táticos coletivos (área da equipe, espalhamento e frequências medianas) no futebol, desde crianças sub-11 até o profissional (N = 120) durante jogos oficiais (N = 12; Campeonato Paulista de Futebol-FPF). Enquanto a velocidade média, e tática tendem a estabilizar os aumentos a partir do sub-15 (ex. sub-15 > sub-13 > sub-11), velocidade máxima (PRO > sub-17 > sub-15, sub-13, sub-11) e percentual de atividades em alta intensidade (sub-20 > PRO, sub-17 > sub-15 > sub-13 > sub-11) exibem ganhos contínuos. Frequências medianas foram maiores nos mais jovens (sub-13, sub-15, sub- 17 > sub-20, PRO), enquanto o percentual de passes completados foi maior nos mais velhos (PRO > sub-17, sub-15 > sub-13, sub-11). Conclui-se que os grupos de idade sub-11 até profissional apresentam diferentes perfis de desempenho de corrida, distribuição dos jogadores em campo, dinâmica de movimentos coletivos e habilidades técnicas, e que o desenvolvimento desses componentes é diferenciado. Treinadores devem estar cientes dos valores de referência apresentados, para selecionar os conteúdos de treino como a intensidade e o volume, específicos para cada grupo de idade. / This master degree thesis is composed by three original manuscripts. The study 1 aimed to compare the kicking performance in trained soccer players aged U9 to U20. Brazilian young players (N = 366) were evaluated by 3-D kinematics (300 Hz) in order to assess ball speed, foot speed, ratio ball/foot speeds, last stride length and distance between support foot and ball. Two-dimensional procedure (60 Hz) was applied to calculate kicking accuracy. Ball speed increases 103% from U11 (48.54±8.31 km/h) to U20 (98.74±16.35 km/h). In contrast, foot speed exhibited increases of 59% from U11 (49.08±5.16 km/h) o U20 (78.24±9.49 km/h). This is achieved due the improvement on the quality of foot-ball impact (ratio ball/foot speeds U11: 0.99±0.13; U20: 1.26±0.11 a.u.) (p < 0,001). Mean radial error and accuracy appears impaired during the growth spurt (U13-U15). In conclusion, Biomechanical parameters of kicking performance have different developmental characteristics. The study 2 investigated the kicking performance (N = 105 selected players) of U11 to U20 age-groups, focused in linear velocities, angular joint displacement and angular joint velocities of the dominant lower limb. Possible differences between groups were assessed. Within each group, influence of playing status (starters, non-starters and substitutes without participation), and peak height velocity (PHV) index on kicking performance was also examined. Lower changes in terms of speeds angular adjustments occur between U11 and U13. During U15 the greater increases was verified, for both velocities and proximal-distal transference, due to several angular adjustments. Also, this is a critical phase to ensure the continuity of players competing in soccer, in which kicking performance discriminate playing status, favoring starters. PHV did not influenced performance parameters in all age-groups. It was concluded that the development rate is not constant in selected players from U11 to U20. The aim of the study 3 was to evaluate performances regarding match-running (e.g. total distance covered, and percentage at various speed zones), skill-related (e.g. involvements with the ball, passes, ball touches, touches per possession, duels and kicks) and also dynamics of collective movements across the pitch (team surface area, spread and median frequencies of the signal), simultaneously, during official matches (N = 12, São Paulo First Division Championship-FPF), in high-level Brazilian U11 to professional players (N = 120). It found that while mean speed and tactical index tends to stabilize the increases from U15 (e.g. U15 > U13 > U11), maximal sprinting speed (PRO > U17 > U15, U13, U11) and percentage of very high-intensity activities (U20 > PRO, U17 > U15 > U13 > U11) exhibit improvements continuously with the age. Median frequencies were greater in younger (U13, U15, U17 > U20, PRO), while successful passes percentage were greater in older (PRO > U17, U15 > U13, U11). In conclusion, U11 to professional age-groups have different activity profiles (running, tactical and skill-related), and the development of these components are not equal. Coaches should be aware of the reference values presented in order to select training content into a periodization similar to a real competition match (e.g. volume and intensity) specific for each age-group.

Master of Science / Department of Mechanical and Nuclear Engineering / Dale E. Schinstock / Control theory is the study of feedback systems, and a methodology investigated by many engineering students throughout most universities. Because of control theory's broad and interdisciplinary nature, it necessitates further study by application through experimental learning and laboratory practice. Typically, the hardware used to connect the theoretical aspects of controls to the practical can be expensive, big, and time consuming to the students and instructors teaching on the equipment. Alternatively, using cheaper sensors and hardware, such as encoders and motor drivers, can obfuscate the collected data in a way that creates a disconnect between developed theoretical models and actual system results. This disconnect can dissuade the idea that systems can and will follow a modeled behavior. This thesis attempts to assess the feasibility of a piece of laboratory apparatus named the NERMLAB. Multiple experiments will be conducted on the NERMLAB system and compared against time-tested hardware to demonstrate the practicality of the NERMLAB system in control theory application.

Le rôle du noyaux de la base dans le contrôle moteur reste une question ouverte. Nous avons conçu une tâche motrice contrôlée dite « start-stop » chez la souris, permettant de quantifier les paramètres cinématiques associés à l'action. Les enregistrements extracellulaires ont démontré que notre tâche recrute 8 classes différentes de neurones dans le striatum. Le groupe « quoi » était composé des neurones « Beginning » et « End », activés au début ou à la fin de la séquence motrice, respectivement. Le groupe « comment » était composé des neurones « Running », « Onset » et « Offset » qui représentaient l'ensemble de l'exécution de la séquence motrice et étaient corrélées aux performances de vitesse. Nous avons aussi signalé la présence de les cellules « Immobility » activées pendant l'immobilité. La comparaison des performances au cours d’essais réussis par rapport à des mouvements spontanés a montré que la fraction des différentes classes de neurones striataux reste stable. Cependant, la fraction de cellules modulant leur activité en fonction de la séquence était fortement diminuée dans les mouvements spontanés par rapport aux essais réussis, et l'activité des cellules « Running » étaient moins corrélées avec la vitesse et la durée de la course de l'animal. Nos données sont cohérentes avec un modèle de fonctionnement des ganglions de la base dans lequel l'activité striatale est organisée d'une manière temporellement précise pour initier, maintenir et mettre fin à l'activité des séquences motrices. Des tests d'optogénétique en cours permettront de confirmer les relations causales supposées entre l'activité striatale et la mise en œuvre de mouvements spécifiques. / The precise role of the basal ganglia in the control of motor actions is still under debate. We designed a well-controlled start-stop running paradigm for mice, that enabled to quantify the kinematic parameters associated with motor execution. Extracellular recordings demonstrated that our task massively recruited 8 different functional striatal classes that modulated their activity at distinct phases of the sequential action and immobility. The “what” group comprised Beginning and End neurons which were specifically tuned at the beginning or at the end of the motor sequence, respectively. The “how” group was the most representative and comprised Running, Onset and Offset cells which, cooperatively represented the entire execution of the motor sequence and were well correlated with speed performance. Strikingly, we also reported the presence of the Immobility cells that specifically fired during immobility periods. Comparison of performances during good trials versus spontaneous runs showed that the fraction of the different striatal classes remained stable. However, the fraction of cells with significant sequence-related modulation was prominently decreased in spontaneous compared to good trial runs, and the activity of the Running cells was less correlated with animal's running speed and duration. Our data are consistent with a basal ganglia model where striatal activity is coordinately organized in a temporally precise manner to initiate, maintain and terminate motor sequences. Ongoing experiments with optogenetics techniques (developed during this thesis) will confirm inferred causal relationships of striatal activity to specific motor implementations.

Neuromodulation allows flexibility within networks of neurons controlling rhythmic motor behaviours. This thesis explores how purinergic and cholinergic neuromodulation contributes to the functioning of spinal motor networks in mice. Purinergic modulation in the spinal cord was investigated using neonatal mouse in vitro spinal cord preparations in which locomotor-related bursts of activity were pharmacologically induced. Ventral root recordings from these preparations showed that glia release ATP, which is broken down to adenosine and binds to A1 adenosine receptors to reduce the frequency of locomotor-related bursts. Whole-cell patch-clamp recordings showed that adenosine opens leak potassium channels in ventral horn interneurons, leading to general network inhibition. Interestingly, although adenosine reduces synaptic inputs in interneurons and motoneurons, interneurons show a reversible hyperpolarisation and reduction of miniature postsynaptic currents (mPSCs) in response to adenosine, while motoneurons show a reversible depolarisation and no change in mPSCs. It was therefore concluded that adenosine opens leak potassium channels in ventral horn interneurons which reduces the speed of locomotor-related output from the whole network. However, motoneuron activity is prevented from falling so far as to cause muscle contraction to cease. Cholinergic modulation of mouse spinal motor networks was also investigated. Pitx2+ cells, known to be the source of cholinergic C-bouton inputs to motoneurons, were selectively transfected with channelrhodopsin and light was used to activate the Pitx2+ cell population. Pitx2+ cell activation was found to reduce rheobase and range of firing in small numbers of spinal motoneurons. The role of Pitx2+ cells in behaviour was also investigated by testing adult mice before and after Pitx2+ cell ablation. No difference in performance was observed in reaching or ladder walking tasks. It therefore seems likely that activation of Pitx2+ cells modulates motoneurons via C bouton synapses, but this modulation is task-dependent and is not critical for goal-directed movements requiring fine motor control.