Hopping is considered a mass-spring model movement in which the leg supports the center of mass. There is a preferred hopping frequency and hopping outside of that frequency is more difficult and requires more energy. Leg stiffness has been shown to be an important factor when hopping at different frequencies in young adult populations. The purpose of this study was to observe how a still-developing preadolescent population would modify leg stiffness while hopping at different frequencies and if they have similar motor control strategies compared to young adults. The subjects hopped on their dominant leg to the beat of a metronome at one of four frequency conditions based on their calculated preferred frequency, MP (preferred frequency), MM (20% increase), MF (40% increase), and MS (20% decrease). It was found that this population could change their hopping frequency and they achieved this by manipulating their leg stiffness. At the higher frequency conditions there was less movement of the toe and the center of mass in both the vertical and horizontal directions, including decreased hopping height, decreased COM displacement and COM range of motion. Preadolescents demonstrated an adult-like ability to increase leg stiffness and modulate movement of the toe and the COM while adapting to a range of hopping frequencies. This ability could translate into other mass-spring model movements such as running and jumping.

Orientador: Tamotsu Hirata / Resumo: A natação competitiva tem evoluído a cada ano que passa em vários países do mundo. Exemplos como os Estados Unidos e Austrália estão sendo seguidos em outras partes do planeta. Para chegar no nível elevado de performance é preciso que o esporte tenha como apoio pesquisas elaboradas para o aproveitamento direto entre os treinadores. No Brasil este conceito tem crescido, mas a natação ainda é carente em alguns aspectos, como por exemplo, as pesquisas para avaliação na área biomecânica. Sabe-se que a pesquisa nesta área requer um custo elevado de equipamentos e mão de obra especializada, porém os dados fornecidos são de grande valia para os treinadores e atletas que podem através disso aperfeiçoar sua técnica. Um bom exemplo são as pesquisas feitas com finalidade de corrigir a performance de saída dos nadadores. Neste trabalho é proposto um sistema de análise cinemática e dinâmica da performance de saída com base na cinemetria em que o centro de massa é calculado a cada momento no gesto de saída. Através desse método foram verificados os dados de Tempo de Bloco, Tempo de Vôo, Tempo Submerso, Tempo Complementar, Tempo Total de saída (15m), Ângulo de Abandono do bloco, Ângulo de Entrada na água, Velocidade Vertical e Horizontal de abandono do bloco, Velocidade Vertical e Horizontal de entrada na água, o Pico de Força de Inércia Horizontal e a Força de Inércia Horizontal no abandono. Os resultados foram considerados válidos neste trabalho e coerentes com os pesquisados na literatura, tornando o sistema de medição proposto adequado para futuras pesquisas. / Abstract: The competitive swimming has developed every year around the world. Samples with the United State and Australia were being following in others parts of planet. For to reach in high level of performance is need that the sports has with aid research developed to the direct progress between coachs. In Brazil this concept has growed, but the swimming still is deficient in some aspects with the researchs for biomechanics avaliation.The research in this area need expensive equipments and especialist professional, however the statistcs datas are the most important to coachs and athletics to improve your thecnique. The good example are research with the objective to improve the performance of swimmer's starts. In this work is propose the analysis kinematics and dynamics of start in swimming based in cinemetry that the center of mass is calculated every moment in start movement. Through this method was verified the block time data, flight time, underwater time, complementar time, total time of start (15m), block leave angle, entry angle, vertical and horizontal speed of block leave, vertical and horizontal speed of entry, top horizontal inertia force and the horizontal inertial force in leave. The results were considered valid in this work and coherent with researched, becoming the propose meter system adequate to future researchs. / Mestre

Stair climbing is a common activity encountered in daily living. Stair ascent is a demanding task that requires a large range of motion of the joints, strong muscle strength, good cardiovascular fitness, and fine balance control. Given this, the activity can be difficult for different populations that lack muscle strength and coordination. To train and assist people in this activity, several robotic platforms have been proposed, but these limit the natural motion of the individual. For example, these devices fix the placement of the feet and reduce the natural swing of the lower limbs. This makes it difficult to manipulate the center of mass, which is crucial to stair ascent. In this dissertation, we present a novel parallel cable-driven platform in which the end effector is the user’s pelvis; the stairmill tethered pelvic assist device. This architecture allows the user to retain their natural movement and relation between the feet and the center of mass, all while applying three dimensional forces on the pelvis during continuous stair ascent on a revolving stairmill. In this work, we show the design, fabrication, and validation of this robotic system. Various force strategies were explored during stairmill ascent using this robotic platform. A characterization experiment was conducted to investigate gait performance and muscle coordination. Two simple interventions were tested to show the potential for long-term training program. This work sheds light on the different strategies of stair climbing and how we can use cable driven platforms to train and assist individuals during this challenging task. The knowledge gained by this work allows for the expansion of designing training paradigms for stair climbing with natural motion. These can assist individuals in improving their quality of life.

No description available.

Medical molecular imaging with positron emission tomography (PET) is sensitive to patient motion since PET scans last several minutes. Despite advancements in PET, such as improved photon-pair time-of-flight (TOF) difference resolution, motion deformations limit image resolution and quantification. Previous research of head motion tracking has produced the data-driven centroid-of-distribution (COD) algorithm. COD generates a 3D center-of-mass (COM) over time via raw list-mode PET data, which can guide motion correction such as gating and event rebinning in non-TOF PET. Knowledge gaps: COD could potentially benefit from sinogram corrections used in image reconstruction, while rebinning has not extended to TOF PET. Methods: This study develops COD with event mass (incorporating random correction and line-of-response (LOR) normalization) and a simplistic TOF rebinner. In scans of phantoms and moving heads with F11 flouro-deoxy-glucose (FDG) tracer, COD alternatives are evaluated with a signal-to-noise ratio (SNR) via linear fit to image COM, while rebinning is evaluated with mean squared error (MSE). Results: COD SNR did not benefit from a corrected event mass. The prototype TOF rebinning reduced MSE, although there were discretization errors and event loss at extreme bins for LOR and TOF due to the simplistic design, which introduced image artifacts. In conclusion, corrected event mass in COD is not promising, while TOF rebinning appears viable if techniques from state-of-the-art LOR rebinning are incorporated.

O termo lateralidade é usado para definir a preferência para executar os movimentos com uma das mãos ou um dos pés conhecidos como preferência lateral. Essa preferência pode acarretar a modificação no padrão de movimento em determinadas ações de jogo. O objetivo do trabalho é analisar a trajetória do Centro de Massa (CM) do salto com queda lateral de goleiros de futebol e avaliar possíveis assimetrias originadas pela preferência lateral. Participaram do estudo dez sujeitos do sexo masculino, com idade entre 18 á 34 (21,6 ± 5,1) anos, massa corporal média 88,7 kg ± 8,5, estatura média 191 cm ± 4 e gordura corporal relativa média 11,6% ± 2,6 com o tempo médio de treino 10,9 ±5 anos e todos atuaram na Série A do Campeonato Paulista de 2014. No presente estudo o objetivo foi analisar a trajetória do CM do salto com queda lateral de goleiros de futebol quanto ao lado preferido e não preferido e a possível influência da assimetria lateral. Com base nos resultados obtidos nesse estudo foi possível concluir que o tempo de reação na condição sem conhecimento prévio do local de lançamento da bola foi significativamente maior que na condição com conhecimento prévio de lançamento da bola. As variáveis deslocamento do CM, tempo para atingir a velocidade pico, velocidade pico, velocidade média, aceleração média e ângulo vertical não houveram diferenças quando comparado lado preferido e não preferido, com e sem informação do local de lançamento da bola. O ângulo frontal houve diferença quando comparado as condições com informação e sem informação. Os goleiros estudados apresentaram no inventário de lateralidade uma preferência lateral, que indicando uma possível condição de assimetria. Contudo, isso não foi um fator determinante para modificar as variáveis cinemáticas analisadas correspondentes ao desempenho motor do salto lateral nas cobranças de pênaltis, não apresentado correlação do inventário de lateralidade com os desempenhos analisados. / The term laterality is used to set the preference to execute movements with a hand or a foot known as lateral preference. This preference may lead to a change in the pattern of movement in certain game actions. The objective is to analyze the trajectory of the mass center (CM) side diving of the soccer goalkeepers and evaluate possible asymmetries caused by the lateral preference. Study participants were ten male subjects, ages 18 to 34 will (21.6 ± 5.1) years, mean body weight 88.7 kg ± 8.5, average height 191 cm ± 4 and body fat relative average 11 6 ± 2.6% with the average time of training 10.9 ± 5 years and all acted in Serie A of the 2014 Championship. In this study the objective was to analyze the CM trajectory with side diving of the goalkeeping football on the preferred side and not preferred and the possible influence of lateral asymmetry. Based on the results obtained in this study it was concluded that the reaction time provided without prior knowledge of ball launch was significantly higher than provided with prior release of the ball. The displacement of the MC, the time to reach peak velocity, peak velocity, mean velocity, acceleration and average vertical angle there were no differences compared preferred and non-preferred side, with and without information ball launch site. The front angle was no difference when compared with the conditions information and without information. Despite the goalkeepers stand out a side preference in inventory laterality demonstrating a possible asymmetry condition, but that was not presented in the analyzed variables corresponding to motor performance in the penalty shoot-out, not shown correlation of inventory handedness with the analyzed performance.

Abstract This project illustrates the use of the human's ability to balance according to his center of gravity as demonstrated in two applications. The center of gravity of a human is explained in detail in order to use it in controlling the Aldebaran NAO robot and in the robot-assisted balance training. The first application explains how a humanoid robot can mimic a human's movements via a three dimensional depth sensor where the sensor analyzes the position of a user's limbs and how the robot can lift one foot and balance on the other by redistributing the its body mass when the user lifts his foot. The results showed that this algorithm enabled NAO to successfully mimic the users' arms, and was able to balance on one foot by repositioning its center of mass. The second application investigates how individuals with stroke lean when undergoing robot-assisted balance training. In some instances, they can develop inappropriate leaning behaviors during the training. The Kinect sensor is used to assist in optimizing patients' results by integrating it with the training program. The results showed that the Kinect sensor can improve the efficiency of the process by giving users graphical information about their mass distribution and whether they are leaning correctly or not.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2004Bitstream added on 2014-06-13T19:37:20Z : No. of bitstreams: 1 cipolli_eac_me_guara.pdf: 432634 bytes, checksum: 7111c1b1d773693407d4341ec117c888 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / A natação competitiva tem evoluído a cada ano que passa em vários países do mundo. Exemplos como os Estados Unidos e Austrália estão sendo seguidos em outras partes do planeta. Para chegar no nível elevado de performance é preciso que o esporte tenha como apoio pesquisas elaboradas para o aproveitamento direto entre os treinadores. No Brasil este conceito tem crescido, mas a natação ainda é carente em alguns aspectos, como por exemplo, as pesquisas para avaliação na área biomecânica. Sabe-se que a pesquisa nesta área requer um custo elevado de equipamentos e mão de obra especializada, porém os dados fornecidos são de grande valia para os treinadores e atletas que podem através disso aperfeiçoar sua técnica. Um bom exemplo são as pesquisas feitas com finalidade de corrigir a performance de saída dos nadadores. Neste trabalho é proposto um sistema de análise cinemática e dinâmica da performance de saída com base na cinemetria em que o centro de massa é calculado a cada momento no gesto de saída. Através desse método foram verificados os dados de Tempo de Bloco, Tempo de Vôo, Tempo Submerso, Tempo Complementar, Tempo Total de saída (15m), Ângulo de Abandono do bloco, Ângulo de Entrada na água, Velocidade Vertical e Horizontal de abandono do bloco, Velocidade Vertical e Horizontal de entrada na água, o Pico de Força de Inércia Horizontal e a Força de Inércia Horizontal no abandono. Os resultados foram considerados válidos neste trabalho e coerentes com os pesquisados na literatura, tornando o sistema de medição proposto adequado para futuras pesquisas. / The competitive swimming has developed every year around the world. Samples with the United State and Australia were being following in others parts of planet. For to reach in high level of performance is need that the sports has with aid research developed to the direct progress between coachs. In Brazil this concept has growed, but the swimming still is deficient in some aspects with the researchs for biomechanics avaliation.The research in this area need expensive equipments and especialist professional, however the statistcs datas are the most important to coachs and athletics to improve your thecnique. The good example are research with the objective to improve the performance of swimmer's starts. In this work is propose the analysis kinematics and dynamics of start in swimming based in cinemetry that the center of mass is calculated every moment in start movement. Through this method was verified the block time data, flight time, underwater time, complementar time, total time of start (15m), block leave angle, entry angle, vertical and horizontal speed of block leave, vertical and horizontal speed of entry, top horizontal inertia force and the horizontal inertial force in leave. The results were considered valid in this work and coherent with researched, becoming the propose meter system adequate to future researchs.

Nas últimas décadas a população idosa vem aumentando rapidamente. Com o avanço da idade, os indivíduos têm diversas perdas morfológicas, funcionais e mecânicas. Assim, torna-se cada vez mais relevante abordar questões relacionadas às capacidades físicas dessa população. Uma variável relevante de análise é o controle postural, o qual é importante na realização das tarefas diárias. As oscilações do centro de massa e movimentos das articulações, obtidas por cinemática, e o centro de pressão, obtido através da plataforma de força, fornecem variáveis que permitem análise do comportamento do controle postural. O controle postural e a execução de dupla-tarefa são amplamente estudados na população idosa. No entanto, a grande maioria de estudos não utiliza ou não fornece dados referentes à validade dos testes adjacentes utilizados ao controle postural. O objetivo central do estudo foi determinar a confiabilidade teste-reteste, a reprodutibilidade intra-avaliador, a objetividade, a sensibilidade e a validade do instrumento (teste do laser) criado para ser utilizado em testes adjacentes ao controle postural (dupla-tarefa). Além disso, objetivou-se comparar o controle postural entre adultos-jovens e idosos em diferentes alturas com desafio de duplatarefa. Também foi objetivo desse estudo, verificar as correlações entre variáveis do centro de massa (COM) e do centro de pressão (COP) em idosos na situação de controle postural quase-estático. Para obtenção dos dados cinemáticos foi utilizado o sistema VICON e os dados do COP foram obtidos através de uma plataforma de força AMTI OR6-6-2000. Ambos os instrumentos capturaram os dados simultaneamente na frequência de 100 Hz. O tempo de duração de cada tentativa foi de 30 segundos. Os achados do presente estudo mostraram que o teste do laser possui confiabilidade, validade, reprodutibilidade, sensibilidade e foi válido como teste adicional para o controle postural. Os idosos têm pior controle postural que adultos-jovens, fazendo maior uso da estratégia do quadril na manutenção do equilíbrio. Em situação elevada, os valores de oscilação corporal foram maiores que em nível do solo. Os idosos apresentaram maiores deslocamentos do COP que adultos-jovens tanto elevados quanto em nível do solo. Com relação aos testes utilizados como dupla-tarefa, conclui-se que todos foram capazes de alterar os valores em comparação com tarefa simples. As correlações entre as variáveis área da elipse, velocidade média de oscilação, amplitude ântero-posterior e amplitude médio-lateral do COM e as respectivas variáveis do COP foram todas fortes e significativas. / In recent decades the elderly population is increasing rapidly. With advancing age, individuals have different morphological, functional and mechanical losses. So it is important to address issues related to physical abilities of this population. A relevant variable analysis is postural control, which is important in carrying out daily tasks. The oscillations of the center of mass and movement of the joints, obtained by kinematics, and the center of pressure, obtained by force platform, provide variables that allow analysis of postural control behavior. Postural control and dual-task execution are widely studied in the elderly. However, most studies do not use or do not provide data concerning the validity of the tests used adjacent to the postural control. The main objective of the study was to determine the test-retest reliability, intra-examiner reproducibility, objectivity, sensitivity and instrument validity (laser test) designed for use in adjacent tests to postural control (dual-task). In addition, the objective was to compare the postural control among young adults and elderly people in different heights with dual-task challenge and verify the correlations between COM and COP in the elderly in the static postural control situation. To obtain kinematic data was used VICON system and COP data were obtained through a force platform AMTI OR6-6-2000. Both instruments simultaneously captured data at a frequency of 100 Hz. The duration of each trial was 30 seconds. The finding of this study showed that the laser test has reliability, validity, reproducibility, sensitivity, and was valid as an additional test for postural control. The elderly have worse postural control than young adults, making greater use of the hip strategy in maintaining balance. In high position, the body oscillation values were higher than in the ground. The elderly had higher COP shifts than young adults so high as in the ground level. Regarding the tests used as dual-task, it is concluded that all were able to change the values compared to simple task. The correlations between variables area of the ellipse, average speed of oscillation, anteroposterior amplitude and medial-lateral extent of the COM and its COP variables were all strong and significant.

Falls are one of the most serious problems among the elderly, resulting in fatal physical injuries. Early identification of people at a high risk of falling is needed to facilitate rehabilitation to reduce future fall risk. The overall goal of this dissertation was to develop biomechanical models that identify dynamic limits of balance control in daily functional activities associated with falling, including sit-to-stand (STS) movement, standing (stance perturbation), and walking. Poor performance of STS movement has been identified as one of the risk factors of falls among elderly individuals. We proposed a novel method to identify dynamic limits of balance control during STS movement using whole body center of mass (COM) acceleration and assessed its feasibility to differentiate individuals with difficulty in STS movement from healthy individuals. The results demonstrated that our model with COM acceleration could better differentiate individuals with difficulty in STS movement from healthy individuals than the traditional model with COM velocity. Poor postural control ability is also a risk factor of falls. Postural recovery responses to backward support surface translations during quiet standing were examined for healthy young and elderly adults. The results demonstrated that functional base of support (FBOS) and ankle dorsiflexor strength could be sensitive measures to detect elderly individuals with declined balance control. Our biomechanical model, which determines a set of balance stability boundaries, showed a better predictive capability than the statistical model for identifying unstable balance recovery trials, while the statistical model better predicted stable recovery trials. Lastly, walking requires a fine momentum control where COM acceleration could play an important role. Differences in control of dynamic stability during walking were examined with our proposed boundaries of dynamic stability. Elderly fallers adapted a more conservative gait strategy than healthy individuals, demonstrating significantly slower forward COM velocity and acceleration with their COM significantly closer to the base of support at toe-off, which could be indicative of a poor momentum control ability. Overall, this study demonstrated that COM acceleration would provide further information on momentum control, which could better reveal underlying mechanisms causing imbalance and provide an insightful evaluation of balance dysfunction. This dissertation includes unpublished co-authored material.