Thesis (MOccTher.--Faculty of Health Sciences)-University of Pretoria, 2006. / Includes bibliographical references.

<p>This study is aimed to determine the electromyographic signals of the forearm, using Ag/AgCl electrodes. The four major muscles of forearm, which are providing the bioelectrical currents, have been displayed and analysed to determine the different activities. In order to record the signals, an EMG device has been developed and installed and a schematic has also been presented in this paper.</p>

This study is aimed to determine the electromyographic signals of the forearm, using Ag/AgCl electrodes. The four major muscles of forearm, which are providing the bioelectrical currents, have been displayed and analysed to determine the different activities. In order to record the signals, an EMG device has been developed and installed and a schematic has also been presented in this paper.

Diss. (sammanfattning) Linköping : Univ., 2002. / Härtill 7 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

abstract: During the downswing all golfers must roll their forearms and twist the club handle in order to square the club face into impact. Anecdotally some instructors say that rapidly twisting the handle and quickly closing the club face is the best technique while others disagree and suggest the opposite. World class golfers have swings with a range of club handle twist velocities (HTV) from very slow to very fast and either method appears to create a successful swing. The purpose of this research was to discover the relationship between HTV at impact and selected body and club biomechanical characteristics during a driver swing. Three-dimensional motion analysis methods were used to capture the swings of 94 tour professionals. Pearson product-moment correlation was used to determine if a correlation existed between HTV and selected biomechanical characteristics. The total group was also divided into two sub-groups of 32, one group with the fastest HTV (Hi-HTV) and the other with the slowest HTV (Lo-HTV). Single factor ANOVAs were completed for HTV and each selected biomechanical parameter. No significant differences were found between the Hi-HTV and Lo-HTV groups for both clubhead speed and driving accuracy. Lead forearm supination velocity at impact was found to be significantly different between groups with the Hi-HTV group having a higher velocity. Lead wrist extension velocity at impact, while not being significantly different between groups was found to be positive in both groups, meaning that the lead wrist is extending at impact. Lead wrist ulnar deviation, lead wrist release and trail elbow extension velocities at maximum were not significantly different between groups. Pelvis rotation, thorax rotation, pelvis side bend and pelvis rotation at impact were all significantly different between groups, with the Lo-HTV group being more side bent tor the trail side and more open at impact. These results suggest that world class golfers can successfully use either the low or high HTV technique for a successful swing. From an instructional perspective it is important to be aware of the body posture and wrist/forearm motion differences between the two techniques so as to be consistent when teaching either method. / Dissertation/Thesis / Doctoral Dissertation Exercise Science 2014

Orientador: Fausto Berzin / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T18:13:58Z (GMT). No. of bitstreams: 1 Silva_DanielaCristinadeOliveira_D.pdf: 6119887 bytes, checksum: b62dec11acd94575dd460ba847dfc7a3 (MD5) Previous issue date: 2009 / Resumo: A eletromiografia de superfície é um instrumento potencial para estudos anatômicos, clínicos e cinesiológicos da atividade elétrica muscular e tem sido aplicada para identificar padrões de ativação muscular associados com força e fadiga muscular. A suplementação de creatina tem sido utilizada para aumentar a força e eficiência muscular, bem como diminuir o início da fadiga muscular. Assim, o objetivo deste trabalho foi analisar a atividade eletromiográfica e força dos músculos bíceps braquial (BB), braquiorradial (BR) e flexor ulnar do carpo (FUC) em indivíduos submetidos à suplementação aguda e crônica de creatina. Vinte indivíduos do sexo masculino, idade 18-35 anos, treinados em exercícios resistidos (musculação), foram selecionados para este estudo duplo-cego, randomizado, placebo-controlado. Os voluntários foram divididos em dois grupos: creatina (5 g de creatina e 5 g de maltodextrina, n=10) e placebo (5 g de celulose e 5 g de maltodextrina, n=10). A suplementação foi ingerida quatro vezes ao dia durante os primeiros 7 dias, e uma vez ao dia durante os 49 dias subsequentes. Cada voluntário realizou contração voluntária isométrica máxima (CVIM) de flexão do antebraço e com 30% e 60% da CVIM, antes e após 7 e 56 dias de suplementação. Os sinais eletromiográficos foram captados utilizando eletrodos de superfície passivos conectados a um pré-amplificador, registrados em um eletromiógrafo computadorizado, e analisados pelo software Myosystem-Br1. Uma célula de carga foi empregada para medir a força isométrica máxima durante os testes. Os dados eletromiográficos foram calculados pelos valores de amplitude (RMS - root mean square) e freqüência mediana (FM), e analisados por meio de curva de regressão linear, gerando coeficientes angulares de RMS e FM que foram considerados índices de eficiência e fadiga muscular, respectivamente. Os resultados mostraram que o grupo creatina exibiu aumento da força somente após 56 dias de suplementação (p < 0,05), enquanto nenhuma diferença foi encontrada no grupo placebo. Os músculos BB e BR mostraram decréscimo nos valores de coeficientes angulares de RMS após 7 e 56 dias de suplementação de creatina com 60% da CVIM (p < 0,05). Nenhuma diferença significante foi observada nos valores de coeficientes angulares de FM entre os tempos de suplementação para todos os músculos, em ambos os grupos e cargas. Assim, pode ser concluído que a suplementação crônica de creatina aumenta a força isométrica de flexão do antebraço. Além disso, tanto a suplementação aguda como a crônica de creatina melhoram a eficiência muscular de BB e BR apenas com cargas maiores, porém não tem efeito benéfico na redução da fadiga muscular de BB, BR e FUC, em qualquer intensidade de carga / Abstract: Surface electromyography is a potential tool for anatomic, clinic and kinesiologic studies of muscle electric activity and it has been employed to identify muscular activation levels associated with force and muscular fatigue. Creatine supplementation has been used to augment the strength and muscular efficiency as well to decrease the onset of muscular fatigue. This study aimed to analyze the force and electromyographic activity of biceps brachii (BB), brachioradialis (BR) and flexor carpi ulnaris (FCU) muscles in subjects submitted to acute and chronic creatine supplementation. Twenty resistance-trained male volunteers, aged 18 to 35 years, were selected for this double-blind, controlled-placebo, randomized study. Volunteers were placed into two groups: creatine (5 g creatine and 5 g maltodextrine, n=10) and placebo (5 g cellulose and 5g maltodextrine, n=10). Oral supplementation was given 4 times per day during the first 7days and once a day in the 49 subsequent days. Volunteers performed maximum isometric voluntary contraction (MIVC) of forearm flexion and with 30% and 60% MIVC, before and after 7 and 56 days of supplementation. Electromyographic signs were captured using passive surface electrodes joined to a pre-amplifier, recorded in a computer-connected electromyography and analyzed by the Myosystem-Br1 software. A load cell was used to measure the maximum isometric strength during the tests. Electromyographic data were calculated by values of amplitude (RMS - root mean square) and median frequency (MF) and analyzed by linear regression curve, generating RMS and MF slopes that were considered muscular efficiency and fatigue indices, respectively. Results showed that creatine group exhibited an increase of strength only after 56 days of supplementation (p < 0.05), while no significant difference was found in placebo group. BB and BR muscles showed a decrease of RMS slopes after 7 and 56 days of creatine supplementation with 60% MIVC (p < 0.05). No significant difference was observed in MF slopes among times of supplementation for all muscles in both loads and groups. It can be concluded that the chronic creatine supplementation increases the isometric strength of forearm flexion. Also, both acute and chronic creatine supplementation improve the BB and BR muscular efficiency only with high loads, but do not have beneficial effect on reducing muscular fatigue of BB, BR and FCU, whichever the load / Doutorado / Anatomia / Doutor em Biologia Buco-Dental

The dynamics of wrist rotations are dominated by joint stiffness, which the neuromuscular system must account and compensate for when controlling wrist movements. Because wrist stiffness is anisotropic, movements in some directions require less torque than movements in others, creating opportunities to follow "paths of least resistance." Forearm pronation-supination (PS) can combine with wrist flexion-extension (FE) and radial-ulnar deviation (RUD) to allow the wrist to rotate in directions of least stiffness. Evaluating this hypothesis, and understanding the control of combined wrist and forearm rotations in general, requires a knowledge of the stiffness (the dominant mechanical impedance) encountered during combined wrist and forearm rotations. While wrist and forearm stiffness have been measured in isolation, there are no measurements of coupled wrist and the forearm stiffness. This study characterizes the passive stiffness of the wrist and forearm in combinations of FE, RUD, and PS. Using a wrist and forearm robot, we measured coupled wrist and forearm stiffness for 15° movements from neutral position in 10 young, healthy subjects. We found the stiffness in PS to be significantly smaller than the stiffness in RUD, but similar in magnitude to the stiffness in FE, indicating that the torque required to overcome stiffness in combinations of PS and FE is significantly smaller than the torque required to overcome stiffness in combinations of FE and RUD (assuming equal displacements). The coupled stiffness measured here will enable future studies to determine optimal paths and to compare these optimal paths to observed movements involving wrist and forearm rotations.

Wrist and forearm motion is governed both by its dynamics and the control strategies employed by the neuromuscular system to execute goal oriented movement. Two experiments were conducted to increase our understanding of wrist and forearm motion. The first experiment involved 10 healthy subjects executing planned movements to targets involving all three degrees of freedom (DOF) of the wrist and forearm, namely wrist flexion-extension (FE), wrist radial-ulnar deviation, and forearm pronation-supination (PS). A model of wrist and forearm dynamics was developed, and the recorded movements were fed into the model to analyze the movement torques. This resulted in the following key findings: 1) The main impedance torques affecting wrist and forearm movements are stiffness and gravity, with damping and inertial effects contributing roughly 10% of the total torque. 2) There is significant coupling between all degrees of freedom (DOF) of the wrist and forearm, with stiffness effects being the most coupled and inertial effects being the least coupled. 3) Neglecting these interaction torques results in significant error in the prediction of the torque required for wrist and forearm movements, suggesting that the neuromuscular system must account for coupling in movement planning. A second experiment was conducted in which 10 different healthy subjects pointed to targets arranged on a plane in front of the subjects. This pointing task required two DOF, but subjects were allowed to use all three DOF of the wrist and forearm. While subjects could have completed the task with FE and RUD alone, it was found that subjects recruited PS as well. Hypotheses regarding why subjects would recruit PS even though it was not necessary included the minimization of a number of cost functions (work, effort, potential energy, path length) as well as mechanical interaction between the DOF of the wrist and forearm. It was found that the pattern of PS recruitment predicted from the mechanical interaction hypothesis most closely resembled the observed pattern. According to this hypothesis, the neuromuscular system uses a simplified 2 DOF model of the joints most critical to the task (FE and RUD) to plan the task, while leaving the third DOF (PS) uncontrolled. The resulting interaction torques create the observed pattern of PS movement.

No description available.