• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 186
  • 100
  • 52
  • 36
  • 21
  • 13
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 494
  • 65
  • 45
  • 43
  • 43
  • 42
  • 36
  • 36
  • 34
  • 33
  • 33
  • 33
  • 32
  • 31
  • 30
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

A Test-Retest Reliability Study of Cooper's Test In Adolescents Aged 16-19 Years

Sundquist, Pontus January 2016 (has links)
Background: The maximum rate of oxygen consumption (V̇O2max) can be measured through numerous tests, either directly or indirectly, where direct methods are considered more accurate, whereas indirect methods are more of an estimation with various degrees of reliability. Cooper's Test is one example of an indirect method considered reliable in estimating V̇O2max, with reliability coefficients ranging between 0.897-0.960. Cooper's Test is thus a test that is often used when estimating V̇O2max. However, there is a lack of test-retest research done utilising Cooper's Test on a younger population, which is the reasoning behind this study focusing on adolescents. Aim: The aim of the study was to study the test-retest reliability of Cooper's Test, in adolescents aged 16-19 years. Methods: Twelve healthy adolescents, aged 16-19 years, attending a sports high school participated in a test-retest study (test 1 and test 2) of Cooper's Test. The tests were performed on the short sides of a synthetic grass field, with 66 metres between the two sides, were the participants were instructed to cover as much distance as possible, with high motivation and intensity, for the whole 12 minutes of the Cooper's Test. Each individual participant's data was measured, recorded and later analysed. The total distance covered was then translated into miles and compared to Cooper's original estimated maximal oxygen consumption table for an estimation of each participant's V̇O2max value in ml*kg-1*min-1 from test 1 and test 2. The data from the test-retest and its variance was then analysed by a two-way mixed model of intraclass correlation coefficient (ICC) with an absolute agreement type. Results: The analysed data from test 1 and test 2 of Cooper's Test showed the results of an ICC (95% CI) of 0.06 (-0.353 to 0.544), indicating a substantial error variance between the two separate Cooper's Tests. Conclusion: The data and analysis from this study implied that Cooper's Test was not reliable in the study population, consisting of adolescents. Possible factors influencing the result however were lack of participant motivation and the level of intensity variance during the test-retest of Cooper's Test. Further researchers and amateur and professional users should keep these factors in mind when utilising Cooper's Test to predict V̇O2max. More research is needed within this study's age population to draw any definite conclusions on the reliability of Cooper's test on adolescents.
112

Maximal Versus Non Maximal Muscular Exertions: A Study of Valid Measures Using Isokinetic Dynamometry

Almosnino, Sivan 25 June 2013 (has links)
Muscle strength capabilities are a determinant in the ability to successfully accomplish everyday tasks. As such, the quantification of this aspect of human performance is of interest in many settings. Currently, the validity of muscle strength test results is reliant on the notion that during testing, the participant exerted an effort that is sincere, and that consisted of maximal voluntary contractions. Therefore, the ability to differentiate between maximal and non maximal muscular exertions is of importance. The purpose of this dissertation was to develop and validate probability-based decision rules for differentiating between maximal and non-maximal voluntary exertions of the knee and shoulder joint musculature during isokinetic dynamometry-based testing. For development of the decision rules, healthy participants performed a series of maximal and non-maximal exertions at different testing velocities through a prescribed range of motion. Two different theory-based approaches were subsequently used for decision rule development: the first approach was based on expected better consistency in strength waveform shapes and relative magnitudes during performance of maximal efforts in comparison to non-maximal efforts. The second approach was based on the known force-velocity dependency in skeletal muscles. In terms of discriminatory performance, several of the decision rules pertaining to the knee joint markedly improve upon those previously reported. In addition, a separate investigation demonstrated that the decision rules offer excellent discriminatory performance when applied to test results of participants that have undergone surgical reconstruction of their anterior cruciate ligament. As such, clinicians and researchers may be able to ascertain voluntary maximal effort production during isokinetic testing of the knee joint musculature with a high degree of confidence, and thus be able to rely on such scores for decision-making purposes With regards to the shoulder musculature decision rules, several methodological issues related to test positioning and signal processing need to be addressed prior to consideration of their use in the clinical domain. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2013-06-19 01:12:53.454
113

Maximal oxygen uptake and aging among elite distance runners : a 35 year follow-up

Lyon, Ashley N. January 2003 (has links)
The purpose of this study was to assess the changes in maximal oxygen consumption and cardiorespiratory responses to maximal treadmill exercise of men, who engaged in intense physical training for more than 35-years. Thirteen men were first studied in 1969 and were re-examined in 1992 as a 25-year follow-up. The men were divided into two groups, group 1 (G1) and group 2 (G2). G1 (current age = 54.6 years) consisted of seven men who were Division I cross country runners in the late 1960's, and G2 (current age = 67.5 years) were highly active at the initial testing and were 14 years older than the men of G1 at all test dates. A maximal exercise test revealed a significant decrease in absolute and realtiveVO2ma, over the 35-years for both G1 and G2. G2 experienced a significant decline in VO2max when expressed in relative and absolute terms after the age of 56.5 years which occurred after the 25-year test. Maximal heat rate decreased over the 35-year period for both G1 (187.7 to 165.8 bpm) and G2 (181 to 164.7bpm), however only GI revealed a trend between the 25-and 35-year tests. O2pulse significantly decreased from the initial testing to the 35-year period in G2 (23.1 to 19.5 ml/beat). Body composition changes were evident with aging in that both GI and G2 had a significant increase in percent body fat over the 35-years however, only Gl had a significant increase in body weight at both the 25-and 35-year follow-up.These data suggest that aging and a reduced training regimen may have a significant effect upon VO2m and cardiorespiratory and body composition measures. It appears that after the age of 56 years, a greater reduction in VO2max occurs, which is accompanied by greater changes in stroke volume. Although the aerobic capacity of these men declined over the 35-year period, the values obtained by all men far exceeded the values reported for sedentary and less active men in other studies. Therefore, as previously reported, aging is associated with a reduction in aerobic capacity, however continued endurance training can reduce the rate at which aerobic capacity declines. / Fisher Institute for Wellness and Gerontology
114

The Relationship Between Maximal Aerobic Capacity and Left Ventricular Function with Respect to Age

Page, Kimberly Ann 12 1900 (has links)
In this study, the relationship between maximal aerobic capacity (VO₂max) and left ventricular function was examined in two distinct age groups. A young group (20 - 30 years of age) and an elderly group (over 60 years of age) were compared. Left ventricular function was examined over wide variations in preload accomplished by 5º head-down tilt (TILT) for ninety minutes and lower body negative pressure (LBNP) to -40 mm Hg. with two-dimensional echocardiography. A greater response to an increase in preload (TILT) was related to high VO₂max levels in the young subjects but not in the elderly groups of subjects, suggesting that lower VO₂max levels of the elderly population affected the mechanism of response to the increased levels of preload. Additionally, in the elderly, greater reductions in ventricular volume reflected increased peripheral pooling due to decreased venous tone and/or increased venous compliance during LBNP and were related to increased VO₂max. In the young, VO₂max does not appear to affect the response to reduced preload.
115

The maximal subgroups of the classical groups in dimension 13, 14 and 15

Schröder, Anna Katharina January 2015 (has links)
One might easily argue that the Classification of Finite Simple Groups is one of the most important theorems of group theory. Given that any finite group can be deconstructed into its simple composition factors, it is of great importance to have a detailed knowledge of the structure of finite simple groups. One of the classes of finite groups that appear in the classification theorem are the simple classical groups, which are matrix groups preserving some form. This thesis will shed some new light on almost simple classical groups in dimension 13, 14 and 15. In particular we will determine their maximal subgroups. We will build on the results by Bray, Holt, and Roney-Dougal who calculated the maximal subgroups of all almost simple finite classical groups in dimension less than 12. Furthermore, Aschbacher proved that the maximal subgroups of almost simple classical groups lie in nine classes. The maximal subgroups in the first eight classes, i.e. the subgroups of geometric type, were determined by Kleidman and Liebeck for dimension greater than 13. Therefore this thesis concentrates on the ninth class of Aschbacher's Theorem. This class roughly consists of subgroups which are almost simple modulo scalars and do not preserve a geometric structure. As our final result we will give tables containing all maximal subgroups of almost simple classical groups in dimension 13, 14 and 15.
116

Efeito da perda dental na atividade eletromiográfica da musculatura da mastigação e na força de mordida máxima / Effect of dental loss in electromyography activity in masticatory muscles and maximal bite force

Rosa, Lâner Botrel 10 December 2007 (has links)
A perda dental promove alterações no sistema mastigatório, que podem afetar a parte óssea, a mucosa bucal e o controle muscular. O objetivo deste trabalho foi verificar a força de mordida máxima, a atividade eletromiográfica em diversas situações clínicas e a força de mordida máxima correlacionada com atividade eletromiográfica em 28 indivíduos, sendo 14 parcialmente desdentados e 14 indivíduos dentados. A eletromiografia foi realizada com o Myosystem-Br1, com os eletrodos posicionados nos músculos masseter e temporal, direito e esquerdo e um eletrodo de referência no osso frontal. Os registros da força de mordida foram realizados após os testes eletromiográficos utilizando um dinamômetro com capacidade até 100Kgf, adaptado às condições bucais. O maior valor entre três registros executados foi considerado a força máxima da mordida do indivíduo. Realizou-se a análise estatística dos dados eletromiográficos por meio do teste t com o programa SPSS 12.0. Para a análise entre força de mordida e atividade eletromiográfica foi utilizado o teste de correlação bivariada de Pearson. Verificou-se que a atividade eletromiográfica dos músculos masseter e temporal nos indivíduos parcialmente desdentados foi maior nas condições clínicas de repouso, apertamento dental com algodão, protrusão e lateralidade esquerda. A força de mordida máxima foi maior nos indivíduos dentados nas três regiões. As correlações entre a atividade eletromiográfica e a força de mordida do grupo dentado obtiveram coeficientes positivos para todos os músculos na região molar direita, para o músculo temporal esquerdo na região molar esquerda e para todos os músculos na região incisiva. Para o grupo desdentado parcial somente o músculo temporal esquerdo apresentou correlação positiva na região molar direita. A correlação foi positiva para os músculos masseter direito e temporais, direito e esquerdo na região molar esquerda e, na região incisiva todos os músculos apresentaram correlação negativa. Estes dados evidenciam a grande influência da ausência dental na função do sistema mastigatório. / Dental loss poses changes in the masticatory system, which can affect the boney aspect, oral mucosa, and muscular control. The purpose of this study is to verify the following items in 28 individuals: maximal bite force; electromyographic activity at rest and at maximal voluntary contraction (MVC); dental clenching with cotton; right and left laterality; protrusion; and maximal bite force correlated with electromyographic activity. Participants were 14 partially edentulous and 14 dentate individuals. Electromyography was performed using Myosystem-Br1 with electrodes positioned on right and left masseter and temporalis muscles, and one reference electrode on the frontal bone. Bite force was registered after the electromyographic tests using dynamometer with capacity of up to 100Kgf, adapted for oral conditions. The highest value out of three recordings was considered the individual\'s maximal bite force. Statistical analysis of the electromyographic data was performed means of t test using SPSS 12.0 software. Pearson\'s bivariate correlation test was used for the analysis between bite and electromyographic activity. Partially edentulous individuals showed higher electromyographic activity levels for masseter and temporalis muscles in the clinical conditions of rest, dental clenching with cotton, protrusion, and left laterality. Dentate individuals showed greater maximal bite force in the three regions. Correlations between electromyographic activity and bite force in the dentate group obtained positive coefficients for every muscle in the right molar region, for the left temporalis the left molar region, and for every muscle in the incisive region. For the partially edentulous group, only the left temporalis muscle presented a positive correlation in the right molar region. There was positive correlation for the right masseter and right and left temporalis in the left molar region, and, in the incisive region, every muscle presented negative correlation. These data evidence the strong influence of dental loss over the masticatory system.
117

Um estudo das hipersuperfícies maximais tipo espaço no espaço anti-de Sitter / A study of spacelike maximal hypersurfaces in the anti-de Sitter space

Mascaro, Bruno 07 June 2017 (has links)
Este trabalho apresenta a demonstração de dois teoremas sobre a caracterização de hipersuperf ícies maximais no espaço anti-de Sitter. Ambos os Teoremas 4.0.1 e 4.0.2 caracterizam hipersuperf ícies maximais isométricamente imersas no espaço anti-de Sitter Hn+1 1 com (n-1) curvaturas principais de mesmo sinal, com curvatura escalar constante e curvatura de Gauss-Kronecker constante não-nula, respectivamente, como sendo isométricas ao cilindro hiperbólico H1(c1)Hn1(c2). Também é feito um breve estudo do artigo [17], onde o Teorema 3.0.3 é ferramenta chave para a obtenção dos resultados demonstrados nos Teoremas 4.0.1 e 4.0.2. / This work presents, the demonstration of two theorems about the characterization of maximal hypersurfaces on the anti-de Sitter space. Both Theorems 4.0.1 and 4.0.2 characterize maximal hypersurfaces isometrically immersed in the anti-de Sitter space Hn+1 1 with (n-1) principal curvatures with the same sign, with constant scalar curvature and nonzero constant Gauss-Kronecker curvature, respectively, as being isometric to the hyperbolic cylinder H1(c1) Hn1(c2). Is also done a brief study of the article [17], where the Theorem 3.0.3 is key piece to obtain the results demonstrated in Theorems 4.0.1 and 4.0.2.
118

Associação do polimorfismo da ECA e variáveis fisiológicas determinantes da aptidão aeróbia / Association of the ACE polymorphism and physiological variables correlated with aerobic fitness

Silva, Salomão Bueno de Camargo 13 March 2015 (has links)
O consumo máximo de oxigênio (VO2máx), o limiar ventilatório (LV), ponto de compensação respiratória (PCR) e a economia de corrida (EC) são importantes variáveis fisiológicas associadas com a aptidão aeróbia em corrida. Acredita-se que o polimorfismo da enzima conversora de angiotensina (ECA) possa estar influenciando nos valores dessas variáveis. Contudo, essa relação causal não tem sido amplamente estudada durante a corrida. Dessa forma, o objetivo do presente trabalho foi investigar a associação entre os genótipos da ECA e o VO2máx, LV, PCR e EC mensuradas durante a corrida em esteira. Cento e cinquenta (n = 150) voluntários fisicamente ativos realizaram os seguintes testes: a) teste incremental máximo para determinação do VO2máx, LV e PCR; b) dois testes de velocidade constante (10 km/h e 12 km/h) em esteira para determinação da EC. Os genótipos apresentaram a frequência de: II = 21% ; ID = 52% e DD = 27%. Os resultados apresentaram uma tendência dos indivíduos com o genótipo II apresentarem maiores valores do VO2máx (p = 0.08), bem como a análise do efeito prático apresentou um possível efeito benéfico desse genótipo. No entanto, não foi constatada diferença entre os valores do LV, PCR, e EC entre os indivíduos. Esses resultados sugerem que o genótipo II da ECA pode estar influenciando nos valores da variável máxima relacionada com o consumo de oxigênio / The maximal oxygen uptake (VO2máx), ventilatory threshold (VT), respiratory compensation point (RCP), and running economy (RE) are important variables associated with running aerobic fitness. However, the influence of Angiotensin Converting Enzyme (ACE) polymorphism on these variables determined in running has not been largely investigated. Therefore, the present study aimed to investigate the relationship between ACE genotypes and maximal oxygen uptake, respiratory compensation point, and running economy measured in running. One hundred and fifty (n = 150) physically active young men performed the following tests: a) a maximal incremental treadmill test to determine VO2máx and RCP, b) two constant-speed running test (10 km.h-1 and 12 km.h-1) to determine the RE. The genotype frequency were II = 21 %; ID = 52 %; DD = 27 %. There were a likely beneficial effect and a tendency for the participants with ACE II genotype to have higher VO2max values than DD or ID genotypes (p = 0.08) and the smallest worthwhile effects show a beneficial effect. There were not associations between the genotypes for RCP and RE. These findings suggest that II ACE genotype would influence in maximal variable correlated with oxygen consumption
119

Efeitos do bochecho com carboidrato sobre o desempenho físico, respostas cerebrais e psicofisiológicas de ciclistas mentalmente fadigados durante um teste incremental máximo / Effects of carbohydrate mouth rinse on physical performance, psychophysiological and cerebral responses of mentally fatigued cyclists during a maximal incremental test

Barreto, Cayque Brietzke 14 March 2019 (has links)
Estudos têm demonstrado separadamente, a redução do desempenho aeróbio após uma tarefa de alta demanda cognitiva, e a melhora do desempenho físico através da suplementação com bochecho de carboidrato (CHO), levando à hipótese de que o bochecho com CHO possa atenuar a redução do desempenho aeróbio induzida pela fadiga mental. Portanto, nosso objetivo foi investigar se o uso do bochecho com CHO pode melhorar o desempenho físico, atividade cortical e respostas psicofisiológicas em ciclistas mentalmente fadigados submetidos a um teste incremental máximo (TIM). Métodos: 19 ciclistas treinados (7,56 ± 5,89 anos de experiência, 4,43 ± 0,45 VO2PICO, 359,61 ± 22,92 WPICO) realizaram 5 visitas ao laboratório, sendo as duas primeiras em ordem sequencial e as últimas três balanceadas de acordo com a descrição a seguir: 1) familiarização com TIM (teste preliminar), instrumentos e protocolo de FM; 2) TIM controle (CON) e segunda familiarização com o protocolo de FM; 3) TIM+FM; 4) TIM+FM+CHO; 5) TIM+FM+placebo (PLA). Respostas cardiopulmonares, potencia, percepção subjetiva de esforço (PSE) e valências afetivas foram analisadas durante o TIM, enquanto a atividade de córtex pré-frontal (CPF) e córtex motor primário (CMP) foram analisadas em intervalos regulares (a cada 25 % do TIM preliminar). As respostas psicológicas e atividade de CPF em repouso foram comparadas através do teste t de student, enquanto todas as respostas durante o TIM foram comparadas através de uma de modelos mistos. Resultados: os ciclistas mentalmente fadigados atingiram WPICO ~ 2,18 % e ~ 2.23 % maior na manipulação FM+CHO do que na manipulação FM (P = 0,09) e FM+PLA (P = 0,02). Além disso, o tempo até a exaustão na manipulação FM+CHO foi ~ 2,01 % e ~ 2,14 % maior do que na manipulação FM (P = 0,05) e FM+PLA (P = 0,03), com tamanho de efeito grande em ambos os resultados. A atividade cerebral em CPF foi maior na manipulação MF+CHO e MF+PLA do que na manipulação MF (P = 0,00). Além disso a ativação de CMP também foi maior na manipulação MF+CHO (P = 0,00) e MF+PLA (P = 0,01) do que na manipulação FM, mas nenhuma diferença foi encontrada entre os bochechos. As respostas psicofisiológicas não tiveram diferenças significantes entre as manipulações. Conclusão: O bochecho com CHO foi capaz de atenuar a perda de desempenho comparado à manipulação FM+PLA, mas não comparado à FM. Alémdisso, tanto FM+CHO quanto FM+PLA induziram maior atividade de CPF e CMP comparados à FM / Independent studies have shown a decrease in endurance performance after a high-demand cognitive task, but an improvement on endurance performance with carbohydrate (CHO) mouth rinse, thus leading to a hypothesis that the CHO mouth rinse could attenuate the mental fatiguereduced endurance performance. Therefore, our aim was to investigate if the use of CHO mouth rinse may improve physical performance, cortical activity and psychophysiological responses in mentally fatigued cyclists underwent to a maximal incremental test (MIT). Methods: 19 endurance trained cyclists (7.56 ± 5.89 years of cycling experience, 4.43 ± 0.45 VO2PEAK, 359.61 ± 22.92 WPEAK) performed 5 trials, being the two first visits in sequential and the last three in a counterbalanced order, as it follow: 1) familiarization with MIT protocol (preliminary trial), instruments and MF task; 2) MIT control (CON) and second familiarization with MF task; 3) MIT+CHO; 4) MIT+placebo (PLA). Cardiopulmonary responses, power output, ratings of perceived exertion (RPE) and affective valences were assessed through the MIT, while prefrontal cortex (PFC) and primary motor cortex (PMC) activation were obtained at regular intervals (every 25 % of the preliminary MIT). Psychological responses and PFC activation at rest were compared as using t student test, while the responses during the MIT were compared through a number of mixed model. Results: Mentally fatigued cyclists reached a WPEAK ~ 2.18 % and ~ 2.23 % higher in MF+CHO than MF (P = 0.09) and MF+PLA (P = 0.02), respectively. Moreover, time to exhaustion in MF+CHO manipulation was ~ 2.01 % and ~ 2.14 % greater in MF+CHO than in MF (P = 0.05) and MF+PLA (P = 0.03), respectively. Both performance results showed a large effect size. Cerebral activation in CPF was greater in MF+CHO and MF+PLA than in MF (P = 0.00). Accordingly, PMC activation was also greater in MF+CHO (P = 0.00) and MF+PLA (P = 0.01) than in MF, but no differences have been observed between bouth rinses. Psychophysiological responses has no significant differences between the manipulations. Conclusion: CHO mouth rinse could attenuate the reduced performance compared to MF+PLA but not compared to MF. Moreover, both MF+CHO and MF+PLA induced greater cerebral activity in PFC and PMC compared do MF
120

Topologias maximais com respeito a algumas famílias de subconjuntos / Maximal topologies with respect to some families of subsets

Mercado, Henry José Gullo 18 March 2016 (has links)
Seja (X; t) um espaço topológico e seja F a família de todos os subconjuntos de X que satisfazem uma propriedade topológica dada P (invariante por homeomorfismos). Se acrescentarmos abertos novos à topologia e se F\' é a família de todos os subconjuntos do novo espaço que satisfazem a propriedade P, podemos ter que F ≠ F\'. Se isto sempre acontece, dizemos que o espaço (X; t) é maximal com respeito à família F. Neste trabalho estudaremos os espaços topológicos maximais com respeito a algumas famílias de subconjuntos: discretos, compactos, densos, conexos e das sequências convergentes. / Let (X; t) be a topological space and let F be the family of all subsets of X that satisfy a given topological property P (invariant under homeomorphisms). If we add new open sets to the topology and if F\' is the family of all subsets of the new space which satisfy the property P, we can have F ≠ F\'. If this is always the case, we say that (X; t) is maximal with respect to the family F. We show here some characterizations of maximal spaces with respect to the family of some of its subsets: compacts, dense, discrete and convergent sequences.

Page generated in 0.0354 seconds