Thèses sur le sujet « VO2 kinetic »

Les oxydes doubles lamellaires de cobalt et les oxydes de vanadium ont récemment suscité un vifintérêt suite à la découverte de leurs propriétés thermoélectriques prometteuses. Nos efforts visentà synthétiser de nouveaux composés dérivés de ces systèmes en utilisant la synthèse à l'étatsolide, l'échange d'ions et/ou les techniques hydrothermales. Afin de moduler et d'optimiser leurscaractéristiques thermoélectriques, nous avons ajusté la composition des oxydes de cobalt grâce àdes substitutions appropriées. Au sein du dioxyde de vanadium quasi-1D, nous avons considérétrois différentes structures polymorphes : M1, A et B. Nous avons exploré les différents systèmesen construisant l'ensemble des diagrammes de phases. Nous avons également étudié l'effet de lasubstitution du vanadium par le molybdène et le chrome sur la stabilité de ces structurespolymorphes et caractérisé leurs propriétés électroniques en relation avec les mécanismes detransition de phase.

Hipotezė: 1 tipo cukriniu diabetu sergančių merginų vegetacinių sistemų rodiklių pokyčiai krūvio metu bus didesni, nei šokėjų ir nesportuojančių. Tikslas: Įvertinti 18-22 1 tipo cukriniu diabetu sergančių merginų, greitosios adaptacijos aerobiniams ėjimo krūviams, ypatumus. Tiriamieji: 10 šokėjų, 12 nesportuojančių sveikų merginų, ir 12 sergančių 1 tipo cukriniu diabetu merginų. Tyrimo metodai: 1. Kūno kompozicija 2. dujų analizė 3. pulsometrija 4. biocheminė kraujo analizė 5. standartinis šešių minučių ėjimo krūvis bėgtakiu 6. matematinė statistika. Tyrimo organizavimas: Tyrimas atliktas 2011-2012 metais. Tyrime dalyvavo 34 merginos, kurios buvo suskirstytos į 3 grupes: I grupę sudarė 1 tipo cukriniu diabetu sergančios merginos (n=12), II grupę šokėjos (n=10), III grupę nesportuojančios sveikos merginos (n=12). Tiriamosios buvo 18-22 metų amžiaus. Tiriamosios, atvykusios į Lietuvos kūno kultūros akademijos sporto fiziologijos labaratorija, buvo supažindintos su tyrimu. Prieš tyrimą tiriamosioms buvo atlikta kūno sudėties analizė su „Tanita TBF-300-A “ svartyklėmis. “Tanita TBF-300-A” svarstyklėmis buvo nustatyta tiriamųjų: kūno masė, KMI (kūno masės indeksas), riebalų masė (%), riebalų masė (kg). Visos tyrime dalyvavusios merginos atliko 6 minučių standartinį ėjimo testą bėgtakiu VIASYS LE 200 CE (Vokietija) pagal (1 tyrimo protokolą). 6 minučių standartinio ėjimo testo metu buvo atliktas tiesioginis MDS nustatymas dujų analizatoriumi „Oxycon Mobile“ (Jaeger, Vokietija)... [toliau žr. visą tekstą]
Hypothesis: We thought that type 1 diabetic girls vegetative system parameters during exercise will be higher than the dancers and untrained. The aim of the study: To evaluate the type 1 diabetic quick adaptation of aerobic walking loads, characteristics Subjects: 10 dancers, 12 untrained healthy women, 12 patients with type 1 diabetic women. The methods of the study: 1. Body composition 2. gas analysis 3. pulsometry 4. biochemical blood analysis 5. standard 6-minute treadmill walk test 6. mathematical statistics. The organization of the study: The study was conducted from 2011 to 2012 years. The study included 34 women were divided into 3 groups: group I consisted of type 1 diabetic girls (n = 12), group II dancers (n = 10), III group of healthy untrained girls (n = 12). The participants were between 18-22 years of age. Before the study subjects was performed body composition analysis with Tanita TBF-300-A."Tanita TBF-300-A subjects were found on scales: body weight, BMI (body mass index), fat mass (%), fat mass (kg).All the girls participated in the study, carried out a standard 6-minute treadmill walk test VIASYS LE 200 CE (Germany) in accordance with (1 TABLE). Standard 6-minute walk test was carried out directly by the gas analyzer MDS "Oxycon Mobile (Jaeger, Germany). Total 6-minute walk test in a standard treadmill VIASYS LE 200 CE (Germany) and recovery time using a portable system Oxycon Mobile has been recorded in gas exchange rates of oxygen consumption (VO2)... [to full text]

Gegenstand dieses Beitrags ist eine Methode zur kinetischen Berechnung antriebsentlastender Vorgaben für Rast-in-Rast-Bewegungen bei Mechanismen mit dem Laufgrad 1. Dabei werden die Vorteile der Vorgabe eines Antriebsmomentenprofils über dem Weg aufgezeigt und die numerischen Herausforderungen bei der Anwendung dieser Methode diskutiert. Anhand eines Praxisbeispiels wird diese Methode mit anderen aus dem Stand der Technik bekannten Verfahren verglichen und die entsprechenden Lösungen werden gegenübergestellt
The subject of this paper is a method for the kinetic calculation of drive relieving rise to dwell motions for mechanisms with the degree of freedom of 1. The advantages of specifying a drive torque profile over the path2 are pointed out. Furthermore the numerical challenges in the application of this approach are discussed. By means of a practical example, both the new method as well as known methods and their corresponding solutions are compared

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O surgimento de equipamentos que permitem a análise do consumo de oxigênio (VO2) respiração-a- respiração, tem despertado um grande interesse nos fatores que podem influenciar sua cinética no início do exercício (resposta on). Entre os fatores mais estudados, temos a intensidade do exercício e o nível do treinamento dos sujeitos. Estes dados sugerem que a influência do exercício prévio sobre o VO2 durante o exercício incremental só ocorreria em baixas intensidades de esforço (< 60% VO2max). Os objetivos deste estudo foram: a) analisar a influência do exercício supramáximo realizado previamente, sobre os parâmetros da cinética do VO2 durante a transição repouso-exercício realizado a 50 e 70% VO2max, e b) analisar a influência do exercício supramáximo realizado previamente sobre as respostas cardiorrespiratórias e metabólicas durante o exercício de carga constante realizado a 50 e 70% VO2max. Para este estudo foram utilizados 14 ciclistas bem treinados do sexo masculino (VO2max = 63,4 + 6,5 ml.kg-1.min-1; idade = 21,4 + 3,5 anos; massa corporal = 68,1 + 6,8 kg; estatura = 174,9 + 4,6 cm) que executaram cinco testes: 1) exercício contínuo progressivo até a exaustão voluntária para a determinação do VO2max e as cargas correspondentes a 50, 70 e 120% VO2max e; 2) Quatro testes de carga constante, executados de forma aleatória e em dias separados. Nestes testes os sujeitos pedalaram durante 20 minutos em duas diferentes intensidades de exercício (50 e 70% do VO2max), realizados com e sem a execução prévia de um exercício supramáximo (120% VO2max). Foi analisada a resposta on do VO2 e também as respostas cardiorrespiratórias e metabólicas durante 20 minutos de exercício com carga constante realizados a 50 e 70% VO2max...
The appearance of an equipment that permits the oxygen consumption analysis (VO2) breath by breath has arisen a huge interest in factors which can influence its dynamics in the beginning of exercise (on response). Among the more studied factors, are the exercise intensity and training status. Meanwhile, few studies have analyzed the possible effects of previous exercise on the VO2response during exercise at moderate domain. In our lab, we have verified recently that during an incremental test performed eight minutes after a supramaximum exercise (120% VO2max), there was a significant VO2 increase in the first stage, while, at the intensities between 60% and VO2max, no alteration of VO2 was found, in accordance with the results existent in the literature. These results suggest that the influence of a previous exercise on the VO2 during the incremental exercise would just occur at low intensities (< 60% VO2 max). This model, meanwhile, does not permit to isolate a possible time effect of the exercise, once the highest intensities were always done after two or three stages, which could have favored a recovery, at least partially, of the metabolic conditions. In this way, the data until the present moment do not permit to identify if the normalization of VO2 during the incremental exercise is more dependent on the time and/or the exercise intensity. Therefore, the aims of this study were: a) to analyze the influence of the previous supramaximum exercise on the VO2 kinetics during the rest-exercise transition carried out at 50 and 70% VO2max, and b) to analyze the influence of the previous supramaximum exercise on the cardiorespiratory and metabolic responses during the constant loading exercise performed at 50 and 70% VO2max... (Complete abstract, click eletronic address below)

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The aim of this study was to determine the mode and the level that the physiological and performance variables influence in repeated running sprint ability. To this end, the study used 27 males participants (10 sprint runners (VEL), 8 long-distance runners (FUN) and 9 active subjects (ATI)). In a synthetic track these subjects were submitted to following tests on different days: 1) Incremental testing for determination of VO2max and maximal aerobic velocity (MAV); 2) constant velocity test at 110%MAV for determination of on- and off transition kinetics of VO2 and accumulated deficit oxygen (AOD); 3; 1 minute all-out test for determination of blood lactate concentration ([lac]s) kinetics and off-transition kinetics of VO2; and 4) repeated sprint test (10 sprints of 35 m departing every 20 s) for determine the total time of sprints, best sprint and percentage decrement score (Sdec). In every tests the [lac]s and blood pH were analyzed for observe the difference between maximal value after exercise and rest value (i.e. ∆[lac]s e ∆pH).Total time was significant different between all groups (VEL, 49,5 ± 0,9 s; FUN, 52,6 ± 3,1 s; ATI, 55,9s ± 2,6 s) and Sdec was significant lower in long distance runners compared to other groups (VEL, 8,5 ± 2,5%; FUN, 4,0 ± 2,0%; ATI, 8,3 ± 4,1%). Total time was significant correlated with best sprint (r 0,86), AOD in T110 (r = -,061) and T1min (r = -0,60), ∆[lac]s (r = -0,64) and ∆pH (r = 0,59) in RS, primary time constant (tau1) (r = -0,45) e O2 consumed in fast component after exercise in T1min (r = -0,44). Differently, Sdec was significant correlated with aerobic variables (VO2max, r = -0,59; MAV, r = -0,55; tau1 during exercise, r = 0,41), tau1 after T110 (r = 0,59) and T1min (r = 0,47), as well as, with lactate exchange ability (r 0,75). Therefore, it was concluded that repeated sprint performance is strongly influenced by anaerobic characteristics, while mechanisms related to removal of metabolites originated by anaerobic metabolism and aerobic indices influence to decrease fatigue in RS.
O objetivo deste estudo foi determinar o modo e o grau que as variáveis fisiológicas e de desempenho influenciam no desempenho em sprints repetidos. Para este fim, participaram do estudo 27 homens, sendo 10 corredores velocistas (VEL), 8 corredores fundistas (FUN) e 9 sujeitos ativos (ATI). Em uma pista sintética de atletismo estes sujeitos foram submetidos, em dias diferentes, aos seguintes testes: 1) teste incremental para determinação do VO2max e da velocidade aeróbia máxima (MAV); 2) teste de velocidade constante realizado a 110%MAV (T110) para determinar a cinética do VO2 durante e após o exercício e o déficit de oxigênio (AOD); 3) teste de um minuto máximo (T1min), para determinar a cinética da concentração de lactato sanguíneo ([lac]s) e a cinética do VO2 após o exercício; e 4) teste de sprints repetidos (RS) (10 sprints de 35m, intercalados com 20s de recuperação) para determinar o tempo total dos sprints, melhor sprint e a queda do escore em percentual (Sdec). Em todos os testes a [lac]s e o pH sanguíneo foram analisados para observar a diferença entre o valor máximo após o exercício e o valor de repouso (i.e. ∆[lac]s e ∆pH). Tempo total em RS foi significativamente diferente entre todos os grupos (VEL, 49,5 ± 0,9 s; FUN, 52,6 ± 3,1 s; ATI, 55,9s ± 2,6 s) e Sdec foi significativamente inferior em fundistas comparado aos outros grupos (VEL, 8,5 ± 2,5%; FUN, 4,0 ± 2,0%; ATI, 8,3 ± 4,1%). Tempo total foi correlacionado significativamente com o melhor sprint (r = 0,86), com o AOD no T110 (r = -0,61) e no T1min (r = -0,60), com o ∆[lac]s (r = -0,64) e ∆pH (r = 0,59) do RS, com a constante de tempo primária (tau1) (r = -0,45) e O2 consumido pelo componente rápido após o exercício no T1min (r = -0,44). Diferentemente, o Sdec foi correlacionado significativamente com variáveis aeróbias (VO2max, r = -0,59; MAV, r = -0,55; tau1 durante T110, r = 0,41), tau1 após T110 (r = 0,59) e T1min (r = 0,47), bem como, com a constante de tempo da entrada do lactato no compartimento sanguíneo no T1min (r = -0,75). Portanto, foi concluído que o desempenho em sprints repetidos é altamente influenciado por características anaeróbias, enquanto, mecanismos relacionados à remoção dos metabólitos originados pelo metabolismo anaeróbio e índices aeróbios influenciam para diminuir a fadiga em RS.

Orientador: Benedito Sérgio Denadai
Banca: Camila Coelho Greco
Banca: Marco Tulio de Mello
Resumo: O surgimento de equipamentos que permitem a análise do consumo de oxigênio (VO2) respiração-a- respiração, tem despertado um grande interesse nos fatores que podem influenciar sua cinética no início do exercício (resposta on). Entre os fatores mais estudados, temos a intensidade do exercício e o nível do treinamento dos sujeitos. Estes dados sugerem que a influência do exercício prévio sobre o VO2 durante o exercício incremental só ocorreria em baixas intensidades de esforço (< 60% VO2max). Os objetivos deste estudo foram: a) analisar a influência do exercício supramáximo realizado previamente, sobre os parâmetros da cinética do VO2 durante a transição repouso-exercício realizado a 50 e 70% VO2max, e b) analisar a influência do exercício supramáximo realizado previamente sobre as respostas cardiorrespiratórias e metabólicas durante o exercício de carga constante realizado a 50 e 70% VO2max. Para este estudo foram utilizados 14 ciclistas bem treinados do sexo masculino (VO2max = 63,4 + 6,5 ml.kg-1.min-1; idade = 21,4 + 3,5 anos; massa corporal = 68,1 + 6,8 kg; estatura = 174,9 + 4,6 cm) que executaram cinco testes: 1) exercício contínuo progressivo até a exaustão voluntária para a determinação do VO2max e as cargas correspondentes a 50, 70 e 120% VO2max e; 2) Quatro testes de carga constante, executados de forma aleatória e em dias separados. Nestes testes os sujeitos pedalaram durante 20 minutos em duas diferentes intensidades de exercício (50 e 70% do VO2max), realizados com e sem a execução prévia de um exercício supramáximo (120% VO2max). Foi analisada a resposta on do VO2 e também as respostas cardiorrespiratórias e metabólicas durante 20 minutos de exercício com carga constante realizados a 50 e 70% VO2max... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The appearance of an equipment that permits the oxygen consumption analysis (VO2) breath by breath has arisen a huge interest in factors which can influence its dynamics in the beginning of exercise (on response). Among the more studied factors, are the exercise intensity and training status. Meanwhile, few studies have analyzed the possible effects of previous exercise on the VO2response during exercise at moderate domain. In our lab, we have verified recently that during an incremental test performed eight minutes after a supramaximum exercise (120% VO2max), there was a significant VO2 increase in the first stage, while, at the intensities between 60% and VO2max, no alteration of VO2 was found, in accordance with the results existent in the literature. These results suggest that the influence of a previous exercise on the VO2 during the incremental exercise would just occur at low intensities (< 60% VO2 max). This model, meanwhile, does not permit to isolate a possible time effect of the exercise, once the highest intensities were always done after two or three stages, which could have favored a recovery, at least partially, of the metabolic conditions. In this way, the data until the present moment do not permit to identify if the normalization of VO2 during the incremental exercise is more dependent on the time and/or the exercise intensity. Therefore, the aims of this study were: a) to analyze the influence of the previous supramaximum exercise on the VO2 kinetics during the rest-exercise transition carried out at 50 and 70% VO2max, and b) to analyze the influence of the previous supramaximum exercise on the cardiorespiratory and metabolic responses during the constant loading exercise performed at 50 and 70% VO2max... (Complete abstract, click eletronic address below)
Mestre

This thesis aimed to investigate and model the vo2, response to exhaustive constant intensity running of a short duration. Study I was a Douglas bag based study that compared the vo2, response of physically active subjects to 2, 5 and 8 minute bouts of constant intensity exhaustive exercise performed in both cycling and running. Nine male subjects took part and each completed a ramp test in addition to the three constant intensity tests in both modes of exercise. In the 5 and 8minute tests the subjects achieved 97.0 ± 4.2 and 97.5 ± 2.0 % for cycling, and 98.5 ± 1.8 and 99.2 ± 2.3% for running, of the ramp test Vo,peak. In the 2 minute test, a significantly lower percentage was attained (89.9 ± 5.5% and 91.8 ± 2.5% for cycling and running respectively). In cycling VO, was still increasing over the final minute of the test, whereas in running there was no difference between the last two 30 second samples (P~0.98). It was concluded that in severe intensity exercise of a short duration VO2 may not achieve its maximum and· that in running it may plateau at this sub-maximal rate. Study 2 validated the QP9000 for the measurement of vo2, during running on a breath-by-breath basis. Six male subjects performed a ramp test and tests at rest and at moderate and severe intensities. Each test was performed twice, once using the QP9000 and once using a Douglas bag system. No difference was found for VO, between the two systems (P~0.358). The SD of the differences between the systems across exercise intensities was 97 ± 57 ml.min·1 It was concluded that the QP9000 provides a valid measure of VO, at all exercises intensities. Study 3 investigated the vo2, response of trained runners to 800 m pace running, following a track based time trial. Eight male subjects (Vo,max 68.8 ± 5.6 m1.kg·'min-') took part in the study. That vo2, reached a plateau below Vo, was confirmed by a gradient of -29 ± 275 ml.min-' during the final 30 seconds of exercise. The asymptotic vo2, was only 85.3 ± 6.6 % of the Vo,peak from a ramp test and the response was shown to be extremely fast (time constant (T) of 10.7 ± 3.4 seconds). These breath-by-breath data confirmed the response indicated in Study I. Study 4 explored the single exponential model used to describe the vo2, response and the nature and level of breath-by-breath noise in severe intensity running. Five male subjects performed a ramp test to determine the speed at anaerobic threshold (AT). Each subject then performed five 8-minute runs at a speed corresponding to 90% of the AT and five exhaustive runs at a speed that would elicit exhaustion in about 2-minutes. Analysis of the noise to signal ratio of the severe intensity data showed that the noise was Gaussian and that averaging data over repeated transitions reduced this ratio. Computer simulations of noise equivalent to the noisiest subject's data demonstrated that the use of two repeated severe intensity transitions would give 95% confidence limits of < ± 1.2 seconds for T. Study 5 examined the effect of prior supra AT exercise on the VO, response to exhaustive severe intensity running. Ten middle and long distance runners each completed a ramp test to determine AT and Vo,peak. Subjects then ran exhaustive transitions, lasting approximately 2-minutes, that were preceded by moderate (90% AT) or heavy (50% of the difference between AT and Vo,peak) intensity running. Each transition was repeated. Increased metabolic acidosis (from prior heavy intensity exercise) did not increase the asymptotic vo2, (P ~ 0.226), and this figure represented only about 90% of Vo,peak from the ramp test. The mean response time (MRT) (time to reach 63% of the overall response) was faster following heavy exercise (20.9 ± 1.9 s vs. 18.9 ± 1.0 s, P<0.05). This was however due to a reduction in the duration of the initial (cardiodynamic) phase of the response rather than a speeding of the primary (phase 2) kinetics. Study 6 analysed the differences in this response between sprint and endurance runners. Six male athletes were recruited for each group based on best times for 100 m and 10 000 m. Subjects performed repeated transitions at a speed that would elicit exhaustion in approximately 2-minutes. No difference was found in the model of the VO, response between groups. When all subjects were analysed however a strong negative relationship was demonstrated between Vo,peak (from a ramp test) and the percentage of this Vo,peak that was reached in the constant speed test (r ~ -0.811, P ~ 0.001). It was concluded that the VO, response was dependent on the aerobic capabilities of the individual. In conclusion the thesis demonstrated a vo2, response in trained subjects during exhaustive severe intensity running that was different to that which is suggested by the majority of the literature. The vo2, response tends neither to VO, required nor to Vo,max, but rather tends to a plateau that is sub-maximal. This thesis was unable to identity the mechanisms that might result in such a shortfall in the response. However there appears to be a close link with the aerobic capabilities of the individual.

Gegenstand dieses Beitrags ist eine Methode zur kinetischen Berechnung antriebsentlastender Vorgaben für Rast-in-Rast-Bewegungen bei Mechanismen mit dem Laufgrad 1. Dabei werden die Vorteile der Vorgabe eines Antriebsmomentenprofils über dem Weg aufgezeigt und die numerischen Herausforderungen bei der Anwendung dieser Methode diskutiert. Anhand eines Praxisbeispiels wird diese Methode mit anderen aus dem Stand der Technik bekannten Verfahren verglichen und die entsprechenden Lösungen werden gegenübergestellt.
The subject of this paper is a method for the kinetic calculation of drive relieving rise to dwell motions for mechanisms with the degree of freedom of 1. The advantages of specifying a drive torque profile over the path2 are pointed out. Furthermore the numerical challenges in the application of this approach are discussed. By means of a practical example, both the new method as well as known methods and their corresponding solutions are compared.

There has been an interest in the kinetics of the V02 response during exercise at various intensities. However, most studies focus on the response of submaximal intensities whereas few studies have examined V02 kinetics at severe intensities. The purpose of this study was to evaluate the effect of exercise intensity on V02 kinetics over a range of severe intensities.

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O objetivo deste estudo foi analisar a influência do estado de treinamento aeróbio sobre os efeitos do exercício prévio nos parâmetros da cinética do consumo de oxigênio (VO2) durante o exercício moderado. Para isto, 14 voluntários não treinados (GNT: massa corporal, 81,2 + 10,3 kg; estatura, 1,78 + 0,07 m; idade, 21,2 + 4,0 anos) e outros 14 ciclistas treinados (GT: massa corporal, 68,2 + 6,9 kg; estatura, 1,75 + 0,05 m; idade, 21,4 + 3,5 anos) (indivíduos com no mínimo dois anos de engajamento no treinamento e competições) realizaram um teste progressivo até a exaustão voluntária para a determinação do VO2 máximo (VO2max) e do limiar de lactato (LL). Posteriormente, realizaram em diferentes dias e em ordem aleatória, duas transições repouso-exercício (seis minutos na carga correspondente a 80% do LL), sendo uma delas precedida em oito minutos pelo exercício prévio (dois tiros de um minuto na carga correspondente a 120% VO2max, com um minuto de recuperação entre eles). Durante estes testes foram coletadas amostras de sangue capilar para a determinação da concentração de lactato sanguíneo e também monitoradas as variáveis cardiopulmonares a cada incursão ventilatória. O VO2 de repouso foi aumentado (p < 0,05) pelo exercício prévio (EPS) em ambos os grupos (GNT: 0,836 + 0,061 vs. 0,506 + 0,194 L/min; GT: 0,373 + 0,055 vs. 0,577 + 0,137 L/min). O tempo da resposta média do VO2 (constante tempo da resposta geral 0-360 s) foi significantemente reduzido na condição EPS apenas para o GNT (32,9 + 7,4 vs. 28,6 + 7,7 s; p < 0,05; GT: 25,7 + 5 vs. 23,3 + 5,8 s; p > 0,05). No GT, a Assimptota (VO2 médio dos últimos dois min de exercício) mostrou-se significantemente...
The aim of this study was to analyze the influence of aerobic fitness on the effects of prior exercise on VO2 kinetics parameters during moderate-intensity exercise. Fourteen untrained subjects (UG: body mass, 81.2 + 10.3 kg; height, 1.78 + 0.07 m; age, 21.2 + 4.0 years) and fourteen well trained cyclists (TG: body mass, 68.2 + 6.9 kg; height, 1.75 + 0.05 m; age, 21.4 + 3.5 years) (more than two years of engagement in endurance training and competition) performed one incremental test to voluntary exhaustion, in order to determine the lactate threshold (LT) and maximal VO2 (VO2max). Thereafter, they performed in different days and in random order, two rest to moderate-intensity exercise transitions (six minutes at 80% of LT), preceded by either no prior exercise or prior supra-maximal exercise (two bouts of one min at 120% of VO2max, with rest of one min between them). During the tests, capillary blood samples were collected to determine lactate concentration and the pulmonary gas exchanges were monitored continuously breath-by-breath. Resting VO2 was significantly (p < 0.05) increased by prior exercise (EPS) in both groups (UG, 0.836 + 0.061 vs. 0.506 + 0.194 L/min; TG, 0.373 + 0.055 vs. 0.577 + 0.137 L/min). Mean response time (time constant of overall VO2 response - 0 - 360 s) was significantly speeded by EPS in untrained group (UG: 32.9 + 7.4 vs. 28.6 + 7.7 s, p < 0.05; TG: 25.7 + 5.0 vs. 23.3 + 5.8 s, p > 0.05). In the trained group, the Assimptota (mean last two minutes VO2 value of moderate exercise) was significantly increased by EPS (TG: 2.208 + 0.383 vs. 2.067 + 0.266 L/min, p < 0.05; UG: 1.600 + 0.269 vs. 1.600 + 0.292 L/min, p > 0.05). It can be concluded... (Complete abstract click electronic access below)

The purpose of this study was to evaluate the effect of mode and intensity on VO2 kinetics in the severe intensity domain. Seventeen participants completed 3-7 tests each on a cycle ergometer and treadmill. For each test, Tfatigue, VO2max, Tmean response, VO2GAIN, TVO2max and T@VO2max were determined. Linear regression techniques were used to describe the relationship between TVO2max and Tfatigue . VO2max values were higher in running. The VO2 response profile was faster for running than cycling and faster at higher intensities. The faster VO2 response in running may be associated with larger active muscle mass or differences in muscle activation patterns. The faster response at higher intensities may suggest that VO2 response is driven by O2 demand.

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The present study aimed to evaluate the effects of ischemic preconditioning (IPC) on the ventilatory parameters kinetics in different exercise intensities. Twelve physically active subjects (23.1±1.7 years; 176.1±4.6 cm; 77.6±8.3 kg; 46,7±5,7mL∙kg-1∙min-1) underwent in 5 different days the following tests in an electronically braked cycle ergometer: 1) incremental exercise test until maximal voluntary exhaustion in order to determine maximal oxygen uptake (VO2máx), ventilatory threshold (VT). 2) two constant work rate bouts (CWR) of 6min at moderate intensity (80%VT) interspersed with 30 min of intervention with the IPC (3x5min occlusion/3x5min reperfusion for each thigh, performed intermittently and alternately) in two different days; 3) two repetitions of 6 min CWR in severe intensity corresponding to 70%∆ (i.e., VT + 0,7 x (VO2máx VT)) interspersed by 45min passive rest followed by CPI, in two different days. IPC significantly decreased both the primary component time constant (t1) (19.2±3.3s to 14.8±3,6s) and carbohydrate oxidation (1.43±0.32g∙min-1 to 1.16±0.33g∙min-1) and increased fat oxidation (0.27±0.12g∙min-1 to 0.40±0.12g∙min-1) the for moderate intensity with the VO2 t1 (25,4±9s to 21,2±6,6s) and end VO2 (1689,1±291 para 1745,9±255,7mL∙min-1) did not differ significantly. In severe intensity IPC significantly reduced both t1 (19.2±3.3s to 14.8±3.6s; p<0.05) and end blood lactate concentration (7.48±2.58mM to 7.01±2.20mM, p<0.05), however the slow component amplitude (502,5±204,1 to 529,1±133,5mL∙min-1) and end VO2 (3406,5±474,4 to 3489,7±435,6 mL∙min-1) of VO2 kinetics remain similar. We conclude that the primary component of VO2 kinetics was accelerated by IPC during severe exercise, but not during moderate exercise, suggesting that the main effect of IPC seems to be the increase on O2 delivery induced by a higher blood flow, which corroborate with the periphery limitation hypothesis (metabolic inertia) as the main limit factor for VO2 kinetics at the onset of moderate exercise. For moderate exercise, IPC increased the CO2 retention becoming the VO2 kinetics even slower because the decrease of HCO3- content by ischemia, furthermore, the changes on substrate oxidation observed during exercise after IPC might have occurred for reperfusion-induced increases in FFA delivery and β-oxidation pre-activation
O objetivo deste estudo foi avaliar os efeitos da condição pré-isquêmica (CPI) na cinética dos parâmetros ventilatórios em diferentes intensidades de exercício. Doze indivíduos (23,1±1,7 anos; 176,1±4,6 cm; 77,6±8,3 kg; 46,7±5,7mL∙kg-1∙min-1) fisicamente ativos realizaram em 5 dias diferentes os seguintes testes em cicloergômetro de frenagem eletromagnética: 1) teste de carga incremental até exaustão voluntária para determinação das variáveis máximas (consumo máximo de oxigênio, VO2máx) e submáximas (Limiar Ventilatório, LV); 2) em dois dias diferentes duas repetições de exercício em carga constante (PCC) com 6min de duração em intensidade moderada a 80%LV intercalados com 30min de intervenção com o CPI (3x5min de oclusão/3x5 de reperfusão para cada coxa, de maneira intermitente e alternada); 3) em dois dias diferentes duas repetições de PCC de 6 min em intensidade severa correspondente a 70% do valor entre o VO2 no LV e o VO2máx (70%∆, i.e. LV + 0.7x(VO2max LV)) intercalados por 45min de repouso passivo seguidos do protocolo de CPI. Na carga moderada as variáveis que apresentaram diferença significante da condição controle para a experimental foram: a constante de tempo do componente primário (t1) do VCO2 (43,4±10,4s para 58,2±18,5s), a oxidação de carboidratos (1,43±0,32g∙min-1 para 1,16±0,33g∙min-1) e a oxidação de gordura (0,27±0,12g∙min-1 para 0,40±0,12g∙min-1). O t1 do VO2 (25,4±9s para 21,2±6,6s) e o VO2 final (1689,1±291 para 1745,9±255,7mL∙min-1) não apresentaram diferença significante no domínio moderado. No domínio severo o CPI acelerou significativamente o t1 (19,2±3,3s para 14,8±3,6s) e reduziu a concentração sanguínea final de lactato (7,48±2,58 mM para 7,01±2,20mM) não alterando a amplitude do componente lento (502,5±204,1 para 529,1±133,5mL∙min-1) e o VO2 final (3406,5±474,4 para 3489,7±435,6 mL∙min-1). Podemos concluir que a cinética do componente primário do VO2 (t1) foi acelerada após o CPI no exercício severo, sem efeitos sobre a cinética do VO2 durante o exercício moderado, sugerindo que o principal efeito do CPI parece residir sobre o aumento da oferta de O2 induzida pelas modificações no fluxo sanguíneo, corroborando com a hipótese da limitação periférica (inércia oxidativa) como principal determinante na cinética do VO2 ao início do exercício moderado. No domínio moderado, o CPI aumentou a retenção de CO2 e consequentemente tornou mais lenta a cinética do VCO2 no músculo como conseqüência da diminuição de HCO3- pela isquemia, além disso, a alteração na oxidação de substratos observada durante o exercício subseqüente o CPI provavelmente ocorreu pela maior oferta de AGL e ativação da β-oxidação induzidos pelos períodos de reperfusão

Kroppens syreupptagningskinetik innebär hur snabbt syreupptagningsmekanismerna i kroppen ökar mängden upptaget syre (O2) vid ett påbörjat arbete. Detta påverkar oss dagligen genom att en snabbare reaktion leder till en mindre syreskuld efter arbetet. Syftet med studien var att jämföra VO2-kinetiken mellan ett arm- och benarbete och ett rent benarbete och försöka hitta skillnader mellan dessa. Åtta måttligt tränade försökspersoner (sex män och två kvinnor) rekryterades och fick genomgå tre tester på en specialbyggd arm- och bencykelergometer. Testerna bestod av ett VO2-maxtest (kombinerad arm- och benarbete), ett submaximalt arm- och bentest (AB) och ett submaximal bentest (B) på samma absolut arbetsintensitet (65 % av VO2max) där VO2-kinetik mättes under fyra minuters arbete. Tiden att nå 50 % av VO2-platå (tVO250) var lika mellan AB och B-test (p=0.70). Tiden till VO2-platå var 19 % kortare under arm- och benarbete (AB 82 ± 32 vs B 101 (± 24) sek; p=0.02). Förbrukat O2 under testtiden var större under AB test jämfört med B-test (AB 41 ± 4 vs B 38 ± 4 ml · kg-1; p=0.004). Enligt dessa resultat var syrekinetiken under arm- och benarbetet snabbare jämfört med bara benarbetet, vilket betydde i detta fall att syreskulden i början av arbete under kombinerat arm- och benarbete blev mindre.

When O2 uptake at the lung is used to characterise the oxidative metabolic response to increased contractile activity ( O2 kinetics) in exercising muscle, the O2 profile reflects the combined influence of all involved muscle fibres. Consequently, during high-intensity exercise that mandates activation of fibres with considerable metabolic diversity (e.g., both principal fibre types), response characteristics specific to discrete segments of the recruited pool cannot be determined. The purpose of this thesis was to identify fibre-type-specific effects of conditions that might impact O2 delivery and/or motor unit recruitment patterns on O2 kinetics by using two models that increase fibre recruitment homogeneity during exercise transitions. In four experiments, subjects initiated high-intensity exercise from a moderate baseline (i.e., performed ‘work-to-work’ transitions; M→H) to target higher-order fibres, and in two experiments, subjects cycled at extremely slow and fast pedal rates to skew recruitment toward slow- and fast-twitch fibres, respectively. At mid-range contraction frequency, O2 kinetics (as indicated by the primary time constant, τp) was slower for M→H compared to unloaded-to-high-intensity transitions (U→H) (e.g., 42 v. 33 s; Ch 4) and this slowing was ~50% greater for M→H in a supine body position (decreased oxygenation; Ch 6). Slower kinetics was also present for U→H cycling at fast compared to slow pedal rates (τp, 48 v. 31 s; Ch 8). Conversely, M→H slowing relative to U→H was absent at extreme cadences (36 v. 31 s and 53 v. 48 s for slow and fast, respectively; Ch 7). After ‘priming’ (increased oxygenation), τp was reduced for U→H after fast-cadence priming only (Ch 8) and for M→H in the supine position (Ch 6), but unaffected for upright cycle and prone knee-extension M→H, for which priming reduced the O2 slow component and delayed-onset fibre activation (as indicated by iEMG; Chs 4 and 5). These results provide evidence in exercising humans that high-order fibres possess innately slow O2 kinetics and are acutely susceptible to interventions that might alter O2 delivery to muscle.

Orientador: Benedito Sérgio Denadai
Banca: Mara Patrícia Traina Chacon Mikahil
Banca: Hebert Gustavo Simões
Resumo: O objetivo deste estudo foi analisar a influência do estado de treinamento aeróbio sobre os efeitos do exercício prévio nos parâmetros da cinética do consumo de oxigênio (VO2) durante o exercício moderado. Para isto, 14 voluntários não treinados (GNT: massa corporal, 81,2 + 10,3 kg; estatura, 1,78 + 0,07 m; idade, 21,2 + 4,0 anos) e outros 14 ciclistas treinados (GT: massa corporal, 68,2 + 6,9 kg; estatura, 1,75 + 0,05 m; idade, 21,4 + 3,5 anos) (indivíduos com no mínimo dois anos de engajamento no treinamento e competições) realizaram um teste progressivo até a exaustão voluntária para a determinação do VO2 máximo (VO2max) e do limiar de lactato (LL). Posteriormente, realizaram em diferentes dias e em ordem aleatória, duas transições repouso-exercício (seis minutos na carga correspondente a 80% do LL), sendo uma delas precedida em oito minutos pelo exercício prévio (dois "tiros" de um minuto na carga correspondente a 120% VO2max, com um minuto de recuperação entre eles). Durante estes testes foram coletadas amostras de sangue capilar para a determinação da concentração de lactato sanguíneo e também monitoradas as variáveis cardiopulmonares a cada incursão ventilatória. O VO2 de repouso foi aumentado (p < 0,05) pelo exercício prévio (EPS) em ambos os grupos (GNT: 0,836 + 0,061 vs. 0,506 + 0,194 L/min; GT: 0,373 + 0,055 vs. 0,577 + 0,137 L/min). O tempo da resposta média do VO2 (constante tempo da resposta geral 0-360 s) foi significantemente reduzido na condição EPS apenas para o GNT (32,9 + 7,4 vs. 28,6 + 7,7 s; p < 0,05; GT: 25,7 + 5 vs. 23,3 + 5,8 s; p > 0,05). No GT, a Assimptota (VO2 médio dos últimos dois min de exercício) mostrou-se significantemente... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to analyze the influence of aerobic fitness on the effects of prior exercise on VO2 kinetics parameters during moderate-intensity exercise. Fourteen untrained subjects (UG: body mass, 81.2 + 10.3 kg; height, 1.78 + 0.07 m; age, 21.2 + 4.0 years) and fourteen well trained cyclists (TG: body mass, 68.2 + 6.9 kg; height, 1.75 + 0.05 m; age, 21.4 + 3.5 years) (more than two years of engagement in endurance training and competition) performed one incremental test to voluntary exhaustion, in order to determine the lactate threshold (LT) and maximal VO2 (VO2max). Thereafter, they performed in different days and in random order, two rest to moderate-intensity exercise transitions (six minutes at 80% of LT), preceded by either no prior exercise or prior supra-maximal exercise (two bouts of one min at 120% of VO2max, with rest of one min between them). During the tests, capillary blood samples were collected to determine lactate concentration and the pulmonary gas exchanges were monitored continuously breath-by-breath. Resting VO2 was significantly (p < 0.05) increased by prior exercise (EPS) in both groups (UG, 0.836 + 0.061 vs. 0.506 + 0.194 L/min; TG, 0.373 + 0.055 vs. 0.577 + 0.137 L/min). Mean response time (time constant of overall VO2 response - 0 - 360 s) was significantly speeded by EPS in untrained group (UG: 32.9 + 7.4 vs. 28.6 + 7.7 s, p < 0.05; TG: 25.7 + 5.0 vs. 23.3 + 5.8 s, p > 0.05). In the trained group, the Assimptota (mean last two minutes VO2 value of moderate exercise) was significantly increased by EPS (TG: 2.208 + 0.383 vs. 2.067 + 0.266 L/min, p < 0.05; UG: 1.600 + 0.269 vs. 1.600 + 0.292 L/min, p > 0.05). It can be concluded... (Complete abstract click electronic access below)
Mestre

Einfluss von Traktion auf das Bewegungsverhalten im Fußball - Interaktion zwischen Sohlenkonfigurationen von Fußballschuhen und Kunstrasen der dritten Generation Einleitung/Zielstellung: In den letzten Jahren hat die Entwicklung von Kunstrasen im Fußball enorm an Bedeutung zugenommen. Dabei sind qualitativ hochwertige Kunstrasenplätze (3. Generation, FIFA 2-Star) von der FIFA zum offiziellen Spielbetrieb zugelassen. Neuste Verletzungsstudien und Spielanalysen zeigen, dass sich die Eigenschaften von Kunstrasen und Naturrasen im Bezug auf Verletzungshäufigkeit und Spielgeschehen nicht gravierend unterscheiden (Ekstrand et al. 2006, FIFA 2009d). Doch sind Bewegungsverhalten und Bewegungsstrategien der Spieler auf Kunstrasen im Fußball noch nicht vollkommen verstanden. Ein Hauptkriterium für das Bewegungsverhalten des Sportlers sind die Traktionsverhältnisse – die Interaktion zwischen Schuh und Spielfläche (Sterzing et al. 2007). Hierfür nimmt die Sohlenkonfiguration eines Fußballschuhs, die durch Anzahl, Länge, Anordnung und Material der Nocken modifizierbar ist, eine zentrale Rolle ein. Die Traktionsverhältnisse haben dabei einen Einfluss auf die Leistungsfähigkeit und die Belastung des Sportlers (Shorten et al. 2003). Auf Kunstrasen verwenden Sportler Fußballschuhe mit einer Sohlenkonfiguration, die für Naturrasen entwickelt worden ist. Zum Zeitpunkt dieser Arbeit gab es nur vereinzelte und unsystematische Forschungen bezüglich Sohlenkonfigurationen für Kunstrasen. Somit herrscht eine Diskrepanz zwischen einer „neuen“ verwendeten Spielfläche und „alten“ getragenen Schuhen. In der Bewegungswissenschaft dient eine komplexe Sportschuhforschung dazu, Kriterien wie Traktionsverhältnisse zu untersuchen. Die komplexe Sportschuhforschung setzt sich dabei aus sportmotorischen, subjektiven, biomechanischen und mechanischen Messungen zusammen. Generell richtet sich dabei der Fokus von biomechanischen Messungen auf die genutzte Traktion, von mechanischen Messungen auf die verfügbare Traktion. In diesem Zusammenhang ist das Konzept von verfügbarer und genutzter Traktion von Fong et al. (2009) aufgezeigt. Geeignete Traktionsverhältnisse hinsichtlich einer besseren Leistungsfähigkeit spiegeln sich in höheren biomechanischen Scherkräften und einer besseren subjektiven Bewertung wider. Diese höheren biomechanischen Scherkräfte ermöglichen dem Sportler eine schnellere Laufzeit zu erzeugen. Ungeeignete Traktionsverhältnisse hinsichtlich einer erhöhten Belastung für den Sportler können sich durch eine Kombination oder Verbindung von einer relativ starken Fixierung des Schuhs mit der Spielfläche und erhöht auftretenden Gelenksmomenten der unteren Extremitäten auszeichnen. Das Ziel dieser Arbeit war die Untersuchung von Traktionsverhältnissen verschiedener Sohlenkonfigurationen von Fußballschuhen auf Kunstrasen. Dabei standen sowohl die Leistungsfähigkeit als auch die Belastung des Sportlers im Fokus der Arbeit. Außerdem ist der Einfluss von verschiedenen Rahmenbedingungen, wie Traktionsverhältnisse und verschiedene Bewegungsaufgaben (zeitliche Verzögerung durch Reaktion), auf die Bewegungsausführung von Sportlern bei schnellen Umkehrbewegungen analysiert worden. Methodik: Die Arbeit beinhaltet in einem Zeitrahmen von drei Jahren, drei aufeinander aufbauende Studien mit unterschiedlichem Untersuchungsdesign. Inhalte und Fragestellungen der einzelnen Studien ergaben sich aus den Erkenntnissen der jeweils davor durchgeführten Studie. Einzelne Messungen der Studien fanden entweder im Labor oder auch teilweise auf Sportplätzen als Feldtest statt. Studie 1 untersuchte die Traktionsverhältnisse von drei gängigen Sohlenkonfigurationen (Multinocken, Nocken, Stollen) und eines Prototypen (Kunstrasenmodell) hinsichtlich der Leistungsfähigkeit und funktionaler Nutzung. Inhalte waren ein sportmotorisches, subjektives, biomechanisches und mechanisches Testverfahren. Grundlegende Traktionsvariablen der einzelnen Testverfahren waren die Laufzeit der Probanden durch einen Slalom- und Sprintparcours, die subjektive Einschätzung der Probanden hinsichtlich der Traktionseignung der Sohlenkonfigurationen, Bodenreaktionskraftvariablen, wie horizontale Scherkräfte und der Kraftwert aus Scherkraft dividiert durch Vertikalkraft, bei verschiedenen fußballspezifischen Bewegungsausführungen und mechanische Traktionsvariablen wie Reibungskoeffizienten und Kraftanstiegsraten. In Studie 2 wurde das Bewegungsverhalten bei verschiedenen Sohlenkonfigurationen (Schuh ohne Nocken, Kunstrasenmodell, Nocken, Stollen) mit Hilfe einer biomechanischen Messung (Bewegungsanalyse) bei einer schnell ausgeführten Umkehrbewegung analysiert. Ziel war es, Bewegungsadaptationen aufgrund unterschiedlicher Traktionsverhältnisse kinematisch und kinetisch zu quantifizieren. Grundlegende Untersuchungsaspekte waren hierbei die Gelenksmomente der unteren Extremitäten, die horizontale Fußtranslation, definiert als relative Bewegung des Schuhs auf der Spielfläche während des Bodenkontakts und Winkelverläufe einzelner Segmente und Gelenke. In Studie 3 wurde der Einfluss auf das Bewegungsverhalten bei reaktiven Bewegungsausführungen gegenüber aktiven Bewegungsausführungen mit verschiedenen Sohlenkonfigurationen (Kunstrasenmodell, Nocken) bei einer schnell ausgeführten Umkehrbewegung untersucht. Für diese Studie diente erneut ein biomechanisches Testverfahren (Bewegungsanalyse) zur Analyse von kinematischen und kinetischen Variablen von Reaktion und Sohlenkonfigurationen. Für alle drei Studien stand insgesamt ein Probandenpool aus 58 männlichen Fußballspielern (Alter: 22.4 ± 3.3Jahre, Größe: 177.2 ± 4.6cm, Gewicht: 71.4 ± 5.6kg, Fußballpraxis: 6.4 ± 3.7h/Woche) zur Verfügung. Für die statistische Auswertung konnte mittels der Varianzanalyse für Mehrfachmessungen (ANOVA) und gegebenenfalls einer Post-Hoc Analyse nach Bonferroni zwischen den Sohlenkonfigurationen für sportmotorische und biomechanische Variablen diskriminiert werden. Für subjektive Testverfahren wurde der Friedman-Test verwendet, um zwischen Sohlenkonfigurationen zu unterscheiden. Die statistische Auswertung des mechanischen Testverfahrens erfolgte deskriptiv. In Studie 3 wurden die Daten mit einer zweifaktoriellen ANOVA mit Messwiederholung (Schuh und Reaktion) analysiert. Außerdem wurde in dieser Studie zusätzlich das Joint Coupling verwendet (Heiderscheidt et al. 2002). Ergebnisse: Traktionsverhältnisse auf Kunstrasen der dritten Generation beeinflussen die Leistungsfähigkeit des Sportlers und die Belastungen für den Körper des Sportlers. Flächig verteilte Sohlenkonfigurationen, wie das Multinocken- und Kunstrasenmodell, ermöglichen dem Sportler im Vergleich zu Sohlenkonfigurationen mit sehr langen Stollen, schneller einen Laufparcours zu durchlaufen. Schneller Laufzeiten werden außerdem auch subjektiv von den Sportlern wahrgenommen. Mit diesen Sohlenkonfigurationen erzielen die Sportler außerdem höhere biomechanische Scherkräfte. Hohe mechanische Traktionswerte spiegeln sich dabei nicht zwangsläufig in einer besseren Leistungsfähigkeit der Sportler. Niedrige Traktionsverhältnisse erzeugen bei schnellen Umkehrbewegungen einen vertikaleren Fußaufsatz und reduzierte Gelenksmomente durch ein erhöhtes „Rutschrisiko“. Dies führt zu einem Verlust an Leistungsfähigkeit. Hohe und exzessive Traktionsverhältnisse weisen sowohl eine relativ starke Fixierung des Schuhs mit der Spielfläche als auch hohe Gelenksmomente während des Richtungswechsels auf. Bewegungsadaptationen zwischen Fußballschuhen treten primär im distalen Bereich der unteren Extremitäten auf. Reaktive Bewegungsausführungen zeichnen sich aufgrund einer längeren Reaktionsphase gegenüber aktiven Bewegungsausführungen mit einem ungünstigen Fußaufsatz aus. Dies zeichnet sich bei Umkehrbewegungen durch eine geringere Tibiarotation und Fußadduktion in die neue Bewegungsrichtung aus. Während der Umkehrbewegung wird diese ungünstige Stellung der unteren Extremitäten primär durch einen verstärkten Eversionswinkel im Sprunggelenk kompensiert. Bei reaktiven Bewegungsausführungen sind außerdem die Momente im Knie- und Sprunggelenk erhöht. Unterschiede im Bewegungsmuster bei Sohlenkonfigurationen, die sich im Aufbau nicht stark unterscheiden, können bei verschiedenen Rahmenbedingungen nicht gefunden werden. Diskussion: Sohlenkonfigurationen beeinflussen das Bewegungsverhalten auf Kunstrasen. Niedrige Traktionsverhältnisse spiegeln sich in einem vorsichtigeren Bewegungsverhalten durch ein erhöhtes „Rutschrisiko“ wider, zu hohe Traktionsverhältnisse implizieren durch eine starke Fixierung des Sportlers mit der Spielfläche ebenfalls ein vorsichtigeres Bewegungsmuster. Nach dem Konzept von Fong et al. (2009) zeigen flächig und eben verteilte Sohlenkonfigurationen eine biomechanisch höhere genutzte Traktion. Im Gegensatz dazu, weisen Sohlenkonfigurationen mit langen Stollen eine höhere mechanisch verfügbare Traktion auf. Diese hohen mechanischen Traktionseigenschaften verhindern dabei aber den Sportler mit seiner bestmöglichen Leistung zu agieren. Flächig und eben verteilte Sohlenkonfigurationen wirken sich somit auf Kunstrasen der dritten Generation hinsichtlich der Leistungsfähigkeit und der Belastung für den Körper positiv aus. Dabei erzeugen hohe biomechanische Scherkräfte eine schnellere Abstoppbewegung oder eine kraftvollere Abstoßbewegung, die sich bei schnellen Umkehrbewegungen positiv auf die Bewegungsausführung auswirkt. Laufzeiten durch Parcours (Krahenbuhl 1974, Sterzing et al. 2009) und biomechanische Scherkräfte (Valiant 1988, Morag & Johnson 2001, Shorten et al. 2003) dienen als geeigneten Variablen, um Traktionsverhältnisse hinsichtlich der Leistungsfähigkeit zu untersuchen. Sowohl die Eindringtiefe der Nocken in die spezielle Verfüllung von Kunstrasen als auch die Verteilung der Nocken (Abstand Vorfuß- Rückfußnocken) können dabei die Traktionsverhältnisse von Fußballschuhen beeinflussen. Gelenksmomente und die horizontale Fußtranslation sind geeignete Indikatoren für die Belastungen der unteren Extremitäten während schnellen Richtungswechseln (Torg & Quedenfeld 1971, Ryder et al. 1997). Dabei erzeugen Sohlenkonfigurationen mit hohen mechanisch verfügbaren Traktionsverhältnisse eine niedrige horizontale Fußtranslation und erhöhte Gelenksmomente. Primär finden Adaptationsprozesse durch unterschiedliche Traktionsverhältnisse von Fußballschuhen im distalen Bereich der unteren Extremitäten statt. Dies könnte in Verbindung zu den Aussagen von Studien stehen, die im Fußball dem Sprunggelenk die größte Verletzungshäufigkeit zusprechen (Ekstrand et al. 2006). Reaktive Bewegungsausführungen können als weiteren möglichen Faktor für Verletzungen im Fußball herangezogen werden (Besier et al. 2001a). Hierfür richtet sich bei reaktiv durchgeführten Richtungswechseln erneut der Fokus auf das Sprunggelenk. Durch eine zeitliche Verzögerung bei reaktiven Bewegungen ist die Stellung der unteren Extremitäten des Sportlers im Vergleich zu aktiven Bewegungen weniger in die neue Bewegungsrichtung gebracht. Diese ungünstigere Stellung versucht der Sportler primär über eine verstärkte Eversion des Sprunggelenks zu kompensieren. Diese Kompensation kann für den Sportler ein erhöhtes Belastungsprofil im Sprunggelenk bedeuten (Giza et al. 2003). Allgemein lässt sich feststellen, dass sich ähnliche Sohlenkonfigurationen bei Probandentests hinsichtlich von Traktionsmessungen nur marginal unterscheiden. Eine Kombination von einer Vielzahl an möglichen Adaptationsprozessen, die sich in der Summe nivellieren, scheinen hierbei die Traktionseigenschaften von leicht unterschiedlichen Sohlenkonfigurationen zu überschatten. Eine Kombination aus sportmotorischem, subjektivem, biomechanischem und mechanischem Testverfahren ermöglicht eine allgemeingültige Aussage über Traktionsverhältnisse von Sohlenkonfigurationen auf Kunstrasen. Zusammenfassung: Traktionsverhältnisse, modifizierbar durch unterschiedliche Sohlenkonfigurationen, können die Leistungsfähigkeit der Sportler und die Belastungen der unteren Extremitäten beeinflussen. Auf Kunstrasen der dritten Generation erweisen sich eben und flächig verteilte Sohlenkonfigurationen als Vorteilhaft. Die Belastungen der unteren Extremitäten können sich durch reaktive Bewegungsausführungen weiter erhöhen
Influence of traction properties on movement patterns in soccer – Interaction between sole configurations of soccer boots and 3rd generation artificial turf Introduction/Objective: In recent years the development of artificial soccer turfs got an enormous enhancement. Thereby, high quality types of artificial soccer turfs (3rd generation, FIFA 2-star) were approved for official game play by the FIFA. Latest injury studies and game analysis studies showed that characteristics between artificial turf and natural grass do not differ for injury rates and playing style (Ekstrand et al. 2006, FIFA 2009d). However, movement patterns and movement strategies of soccer players on artificial turf are yet not fully understood. Main criteria for movement patterns of soccer players are traction properties – the player-surface interaction (Sterzing et al. 2007). Therefore, sole configurations of a soccer boot modifiable in numbers, length, geometry and material of studs plays an influencing role. Traction properties influence performance aspects and loads acting on the players’ body (Shorten et al. 2003). On artificial turf players normally use soccer boots with sole configurations designed for playing on natural grass. At the time of this project there were only isolated and unsystemmatic researches according to sole configurations for artificial turf. Thus, there is a discrepancy between a “new” surface and “old” shoes in soccer. In human locomotion a comprehensive assessment of athletic footwear is used to analyse criteria such as traction properties. Comprehensive assessment of athletic footwear contains motor performance, perception, biomechanical and mechanical testing. Generellay, biomechanical measurements focus on utilized traction, mechanical measurements on available traction. In this context, the concept of available and utilized traction is distinguished by Fong et al. (2009). Suited traction properties with regard to performance aspects might be reflected in higher utilized biomechanical shear forces and better perception. These higher biomechanical shear forces enable the player to run faster. Unsuited traction properties with regard to higher loads acting on the players’ body might be displayed by a combination or a linkage of relative fixed shoes with the ground and higher joint moments at the lower extremities. The objective of this doctoral thesis was to investigate traction properties of various sole configurations of soccer boots on artificial turf. Thereby, performance aspects as well as loads acting on the players’ body were on the focus of this doctoral thesis. Additionally, the influence of various basic conditions like traction properties and movement requirements (time constraint due to reaction) on movement pattterns were analyzed during dynamic changes of direction. Methods: This doctoral thesis contained three interdependent studies with several methods in a time period of three years. Topics and questions of each single study were resulted in the findings of the respective study before. Single testing sessions took place either in laboratory environment or partly on the pitch as field testing. In study 1 traction properties of three current available sole configurations (hard ground, firm ground and soft ground) and one prototype (artificial turf) were investigated with regard to performance aspects. Topics were motor performance, perception, biomechanical and mechanical testing. Fundamental traction variables of the testing sessions were running times of subjects through a slalom and acceleration course, traction perception of subjects according to liking of the sole configurations, ground reaction forces variables like horizontal shear forces and force ratio, shear force divided by vertical force, during several soccer-specific movements and mechanical traction variables like traction coefficients and force rising rates. In study 2 movement patterns of various sole configurations (soccer boot without studs, artificial turf, firm ground and soft ground) were analyzed via biomechanical testing (motion analysis) during dynamic turning movements. The purpose of this study was to quantify movement adaptations based on different traction properties. Fundamental research aspects were joint moments of the lower extremities, horizontal foot translation, defined as the relative motion of the shoe on the surface during ground contact and angles of several segments and joints of the lower extremities at touchdown and during turning. In study 3 the influence on movement patterns during reactive movements compared to active movements wearing various sole configurations (artificial turf, firm ground) during dynamic turning movements were investigated. For this study also biomechanical testing (motion analysis) served for analysis of kinematic and kinetic variables of reaction and sole configurations. For all three studies a subject pool of 58 male soccer players (age: 22.4 ± 3.3years, height: 177.2 ± 4.6cm, weight: 71.4 ± 5.6kg, experience: 6.4 ± 3.7h/week) was available. Statistical analysis was done by a one way repeated measured ANOVA and a post-hoc test by Bonferroni for motor performance and biomechanical variables to discriminate between sole configurations, if this was appropriate. For subjective testing, Friedman-test were used to differentiate between sole configurations. For mechanical testing, descriptive statistics were applied. In study 3 the data were analyzed according to two factors (shoe and reaction). Additionally, in this study vector coding was done (Heiderscheidt et al. 2002). Results: On 3rd generation artificial turf, traction properties influenced performance aspects of players and loads acting on the players’ body. Plane distributed sole configurations like hard ground and artificial turf design enabled the players to run faster through a traction course compared to aggressive sole configurations. Faster running times were well reflected by players’ perception. Plane distributed sole configurations were also perceived to be better suited on artificial turf. Additionally, these sole configurations provoked statistically higher biomechanical shear forces. High mechanical traction properties did not automatically lead to better performance aspects of the players. During dynamic changes of direction, too low traction properties provoked more vertical alignment with respect to perpendicular of the lower extremities and lower joint moments. High and excessive traction properties displayed a relative fixed shoe-ground interface as well as high joint moments during dynamic changes of direction. Movement adaptations with regard to soccer boots were primary shown in the distal part of the lower extremities. Reactive movement patterns showed an unsuited foot and leg placement at initial ground contact based on a longer phase of reaction compared to active movement patterns. This unsuited foot and leg placement was shown by reduced tibial rotation and foot adduction through new running direction. During turning this unsuited foot and leg placement were primary corrected by an increased ankle eversion angle. Additionally, higher knee and ankle joint moments were observed for reactive movement patterns. Differences in movement patterns for sole configurations, which are pretty similar in composition, were not found during reactive movements. Discussion: Sole configurations influence movement patterns and movement strategies on artificial turf. Low traction properties indicate more cautious movement behaviour due to risk of slipping, too high traction, implicated by high foot fixation of the player with the surface, indicate also more cautious movement behaviour. Referring the concept of Fong et al. (2009) plane distributed sole configurations provoke higher biomechanical utilized traction. In contrast, pronounced sole configurations with long studs provoke high mechanical available traction. However, these high and excessive mechanical traction properties disabled the subjects to perform with their best capacity. Therefore, plane and evenly distributed sole configurations showed positive aspects for performance and loads acting on the players’ body on 3rd generation artificial turf. Therefore, high biomechanical shear forces produce faster stops or more dynamic propulsion, which influence the performance positively during dynamic changes of direction. Running times through traction courses (Krahenbuhl 1974, Sterzing et al. 2009) and biomechanical shear forces (Valiant 1988, Morag & Johnson 2001, Shorten et al. 2003) were suited variables to detect traction properties according to performance. Penetration of studs into the ground as well as distribution of studs (distance between fore- and rearfoot studs) may play an influencing role on traction properties for soccer boots. Joint moments and horizontal foot translation are suited indicators for the loads acting on lower extremities during dynamic changes of direction (Torg & Quedenfeld 1971, Ryder et al. 1997). Thereby, sole configurations with too high mechanical traction show a combination of decreased horizontal foot translation and increased joint moments. These adaptation processes based on traction properties of soccer boots are primary shown in distal part of the lower extremities. There might be a linkage to reports showing ankle injuries are most common in soccer (Ekstrand et al. 2006). Additionally, reactive movement patterns may be another risk factor for injuries in soccer (Besier et al. 2001a). Due to time constraint for reactive movement patterns the foot and leg placement of the lower extremities are rotated to a lesser extend in new running direction compared to active movement patterns. This unprepared foot and leg placement were primary compensated by an increased eversion at ankle. This compensation might mean increased ankle loadings (Giza et al. 2003). In general it has been showed that pretty similar sole configurations only differ marginal with regard to traction properties during subjects testing. A combination of several adaptation processes, which levelled out in sum, might overshadow traction properties of marginal different sole configurations. A combination of motor performance, perception, biomechanical and mechanical testing allow to give a generally statement about traction properties of sole configurations on artificial turf. Conclusion: Traction properties, modifiable by different sole configurations, could play an influencing role for performance aspects of the players and for the loads of the lower extremities. On 3rd generation artificial turf plane and evenly distributed sole configurations work better than pronounded sole configurations. Loads of the lower extremities could be increased by reactive movement patterns

The elevated CO2 levels, elevated temperature, and lower blood pH that may occur during exercise should enhance O2 delivery to the exercising muscles. It was hypothesized that performance of prior exercise (PE) would result in a faster VO2 response, as well as a reduced slow component contribution, in subsequent exercise bouts. Five women (21 ± 1 yr) and 10 men (23 ± 2 yr) performed nine 6-min bouts of heavy intensity cycle ergometer exercise (i.e., above the ventilatory threshold, individually determined by an incremental test). Three bouts were performed without prior heavy exercise (noPE), three were performed 6 min after a 6-min bout of heavy intensity arm cranking (PEA), and three were performed 6 min after a 6-min bout of heavy intensity cycle ergometer exercise (PEL). Breath-by-breath VO2 data from each of the three sets of three tests were combined and fitted to a two-component model, which ignores the cardiodynamic phase. The primary and slow component amplitudes were truncated to reflect actual increases in VO2 in each phase. The effects of PE on the time constant of the primary component were inconsistent. As hypothesized, the amplitude of the slow component was reduced by PE (noPE vs PEA vs. PEL: 25% > 16% < 14%; p < .05). It is concluded that heavy intensity PE affects characteristics of the VO2 profile in a subsequent bout of heavy intensity leg exercise.

A corrida representa um importante segmento do triathlon, sendo precedida pela prova de ciclismo. A compreensão dos efeitos do ciclismo sobre o desempenho da corrida, portanto, se torna indispensável para a otimização dos resultados finais de uma prova. O objetivo desse estudo foi comparar as variáveis cinemáticas, eletromiográficas e o consumo de oxigênio da corrida no triathlon com àquelas de uma corrida isolada e de uma corrida prolongada. As seguintes variáveis foram avaliadas no presente estudo: (1) freqüência e amplitude de passada; (2) o valor RMS (root mean square) médio do sinal EMG dos músculos bíceps femoral, reto femoral, vasto lateral, gastrocnêmio medial e tibial anterior; e, (3) o VO2. Participaram desse estudo nove triatletas do sexo masculino. O protocolo de avaliação foi realizado em três etapas: (1) teste para obtenção do VO2 máx, realizado em esteira ergométrica; (2) teste que envolveu a sucessão ciclismo-corrida da prova de triathlon (CT), com 40 km de ciclismo, seguidos de10 km de corrida – em um contexto de prova simulada; e (3) teste de corrida prolongada (CP), em que o atleta correu o tempo correspondente aos 40 km de ciclismo somado a 10 km de corrida. Os primeiros 10 km dessa corrida prolongada constituíram a corrida isolada (CI). Os dados cinemáticos, eletromiográficos e o VO2 foram coletados e analisados a partir de três intervalos: 1°, 5° e 9° km de corrida. O nível de significância dos testes estatísticos aplicados foi de α < 0,05. Os resultados não demonstraram diferenças significativas entre as diferentes corridas. Já entre os intervalos, foi verificada uma diminuição da amplitude de passada entre os intervalos 1 e 2, e entre os intervalos 1 e 3, bem como um aumento do valor RMS do músculo vasto lateral do intervalo 1 para o intervalo 3. A partir da análise específica da corrida do triathlon, foi encontrado um aumento da freqüência e da amplitude de passada entre os intervalos. A inexistência de diferenças entre as corridas se contrapõe aos resultados de estudos encontrados na literatura. Entretanto, os presentes resultados podem ser justificados à medida que o VO2 de teste se manteve abaixo do VO2 correspondente ao segundo limiar ventilatório. A existência de diferenças significativas entre os intervalos para algumas das variáveis analisadas pode sugerir a incidência de fadiga no transcorrer da atividade.
Running represents an important segment of triathlon and is preceded by cycling. Therefore, studying the influence of cycling in running performance is essential for performance optimization. The aim of this study was to compare the kinematic and electromyographic variables and oxygen uptake of the triathlon running with a prolonged run and an isolated run. The following parameters were analyzed and compared: (1) the kinematic variables stride frequency and stride length; (2) mean value of the RMS signal of EMG of the biceps femoris, rectus femoris, vastus lateralis, gastrocnemius medialis and tibialis anterior muscles; and, (3) the VO2. Nine male triathletes performed the tests, which were performed on three stages: (1) VO2 max test, performed on a treadmill; (2) 40km of cycling followed by 10km of running time-trial (CT), with 40 km of cycling, followed by 10 km of running – simulated race; (3) prolonged run test (CP): the athletes ran the time corresponding to the 40 km of cycling and more 10 km of running after it. The first 10 km of this prolonged run test was considered the isolated run (CI). Kinematic and eletromyographic variables and VO2 variables were collected and analyzed at three distinct moments: 1°, 5° e 9° km of the run. Statistical tests were applied for an α < 0.05. No significant differences were found between the running types. Between moments, decreased on stride length between moments 1 and 2, and between moments 1 and 3, was observed. There was an increase in the EMG signal RMS of the vastus lateralis from moment 1 to moment 3. In the comparison of triathlon running moments, were found increase in stride frequency and in stride length between moments. No differences were found in literature between running types, a completely opposite result compared to our results. However, these results can be justified for the VO2 values, which remained bellow the VO2 values corresponding to ventilatory threshold. The significant differences between moments of some variables may suggest a fatigue effect in the results.

Le modèle bioénergétique de P.E. di PRAMPERO permet d'expliquer la performance dans les disciplines de locomotion (course à pied, cyclisme, natation, ...) à partir d'une puissance métabolique et d'un indice de la dépense d'énergie par unité de distance parcourue. Néanmoins, pour les épreuves de natation de haute intensité telles que le 100m crawl, le contexte environnemental rend l'estimation de la puissance métabolique d'origine aérobie techniquement difficile. L'objectif de cette thèse est alors de proposer une nouvelle approche des réponses aérobies d'un 100-m nage libre, réalisé dans des conditions les plus proches possible d'une compétition. Le travail expérimental a porté sur des nageurs entraînés. Dans un bassin de 25-m, la procédure propose que les nageurs réalisent une performance sur 100-m nage libre à allure de compétition et trois épreuves (25m, 50m, 75m) réitérant les mêmes allures intermédiaires que celles du 100-m. VO2 est mesuré avant et juste après chaque épreuve, pendant 1min, par rétro-extrapolation. Les valeurs de VO2 mesurées à la fin des épreuves de 25m, 50m, 75m et 100m permettent de reconstruire la cinétique de VO2 d'une épreuve de 100-m. Les résultats contrastent avec les estimations des cinétiques de VO2 publiées précédemment : VO2 augmente plus vite dans la première moitié de l'épreuve (à 50m, VO2 ≈ 94%VO2max), atteint 100 %VO2max au 75ème mètre de l'épreuve puis chute de 7% sur le dernier 25-m. Une estimation de la contribution relative du métabolisme aérobie montre également des valeurs plus importantes que celles publiées jusqu'à ce jour, du fait de l'atteinte précoce de VO2max en cours d'épreuve
The bioenergetic model proposed by P.E. di PRAMPERO explains performance in most human locomotions (running, cycling, swimming, ...) using indexes of metabolic power and energy cost of locomotion. Nevertheless, for 100-m front crawl events, environmental conditions make the aerobic power measurement difficult. The main purpose of this thesis is therefore to propose a new procedure to estimate aerobic responses during a 100-m front crawl event, performed in competition conditions. Trained swimmers participated to this study. In a 25-m swimming pool, the procedure includes a 100-m front crawl performance in competition conditions, and then, three tests (25-m, 50-m, 75-m) following the pacing strategy of the 100-m event. VO2 is not measured during the tests, but before and just at the end of each test with a breath-by-breath method. Each post-test VO2 (after 25m, 50m, 75m and 100m) allows to reconstruct the VO2 kinetics of the 100-m performance. The results differ from previous studies in that VO2 increases faster in the first half of the race (at 50m, VO2 ± 94%VO2max), reaches VO2max at the 75th meter; then a decrease in VO2 corresponding to 7% of VO2max appears during the last 25m. The estimation of aerobic contribution shows higher values than those previously published, because VO2max is reached very early during the race

This thesis developed new methods of modelling oxygen uptake in exercising humans during cycling exercise sessions to steady-state. The results will contribute to the redefinition of conventional methods of data acquisition, processing, and modelling across exercise physiology, sports science, and respiratory disease research and application. The thesis identified misconceptions within current methods of data handling, and proposed innovative methods for improved data modelling.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Introdução: Os pacientes com Miopatia Mitocondrial (MM) e Oftalmoplegia Externa Progressiva (OEP) apresentam disfunção na cadeia respiratória com incapacidade de aumentar a extração de oxigênio muscular e sintetizar ATP aerobicamente, levando à intolerância ao esforço e lentificação da cinética do O2. Quando a extração de oxigênio é comprometida, na tentativa de se manter o consumo de oxigênio muscular, uma hipótese é que estes pacientes poderiam aumentar compensatoriamente a oferta de oxigênio, apresentando, assim, uma resposta hipercinética cardiovascular e ventilatória. Por outro lado, alguns indícios de menor oferta de oxigênio foram encontrados em pacientes com MM, como um menor fluxo sanguíneo muscular no antebraço e uma maior capacidade de produção de ATP após a suplementação de oxigênio. A cinética do O2 na fase de recuperação (REC) nos fornece, assim, subsídios quanto ao pagamento do débito de oxigênio tecidual e ao reabastecimento do estoque de oxigênio sanguíneo após o exercício. Ao nosso conhecimento, a cinética do O2 REC nunca foi avaliada nos pacientes com MM, assim como a integração desta variável com as respostas não-invasivas cardiovasculares e de extração de oxigênio muscular. Objetivo: contrastar as dinâmicas da oferta e da utilização de oxigênio na recuperação do exercício em pacientes com MM; e identificar os principais mecanismos fisiopatológicos da intolerância ao esforço nestes indivíduos. Métodos: Foram avaliadas em 12 pacientes com MM e 12 controles saudáveis, as cinéticas de recuperação: (i) do O2 pulmonar, (ii) da variação na concentração da deoxiemoglobina ([HHb], mensurada pela espectroscopia de raios quasi infravermelhos - NIRS) no vasto lateral, (iii) do débito cardíaco (DC) por bioimpedância transtorácica, após um teste de carga constante de alta intensidade (70% da carga máxima atingida em teste incremental prévio) até o limite da tolerância em cicloergômetro. Resultados: Foram observadas cinéticas mais lentas de reoxigenação da [HHb], ([HHb] = 43,7 ± 21,2 vs 27,5 ± 6,7) e do O2 ( O2 = 58,1 ± 25,1 vs 38,8 ± 7,6) nos pacientes com MM em relação aos controles, respectivamente. Estas respostas foram associadas a uma cinética de DC mais rápida em relação ao O2, nos pacientes comparados aos controles (T½DC * 1,44 / O2 = 1,3 ± 0,4 vs 1,7 ± 0,6). Conclusão: Os pacientes com MM na forma OEP apresentam, na recuperação do exercício de alta intensidade, um pagamento elevado do débito de oxigênio contraído no exercício e reoxigenação mais lenta da [HHb]. Estas respostas, associadas à cinética mais rápida do DC em relação ao O2 são indícios de que possa haver um déficit no transporte de oxigênio microvascular, além do comprometimento mitocondrial característico desta doença.
Background: Mitochondrial Myopathy patients (MM) and Progressive External Ophthalmoplegia (PEO) present with respiratory chain dysfunction and inability to increase muscle oxygen extraction and aerobic ATP synthesis, leading to exercise intolerance and slower O2 kinetics. When oxygen extraction is impaired, in an attempt to maintain muscle oxygen uptake, these patients could increase oxygen delivery, thus exhibiting a hyperkinetic cardiovascular and ventilatory response. On the other hand, some evidence of oxygen delivery impairment was found in MM patients, such as a decrease in muscle blood flow in the forearm and a greater capacity for ATP production after oxygen supplementation. Recovery O2 kinetics provides information on tissue oxygen debt repayment and oxygen blood store replenishment after exercise. To our knowledge, recovery O2 kinetics has never been evaluated in MM patients, as well as its integration with the non-invasive cardiovascular and muscle reoxygenation responses. Objective: to contrast oxygen delivery and utilization dynamics on exercise recovery of MM patients and to identify the main pathophysiologic mechanisms of exercise intolerance in these subjects. Methods: Were evaluated in 12 MM patients and 12 healthy controls, the recovery kinetics of: (i) O2 (ii) deoxyhemoglobin variation ([HHb], measured by near-infrared spectroscopy - NIRS) in vastus lateralis, (iii) cardiac output (CO) by transthoracic bioimpedance, after a high-intensity constant work rate test (70% of maximal workload in a previous incremental test) to the limit of tolerance in a cycle ergometer. Results: We detected slower kinetics for [HHb] ([HHb] = 43.7 ± 21.2 vs. 27.5 ± 6.7) and for O2 ( O2 = 58.1 ± 25.1 vs. 38.8 ± 7.6) in MM patients compared to controls, respectively. Additionally, these responses were associated with a faster recovery CO kinetics in relation to O2 kinetics in MM patients compared to controls (T½DC*1,44 / O2 = 1,3 ± 0,4 vs. 1,7 ± 0,6). Conclusion: Patients with MM and PEO present with a higher oxygen debt and slower reoxygenation kinetics in the recovery of a high-intensity exercise test. Those responses were associated with a faster CO recovery in relation to O2 kinetics, indicating a microvascular oxygen transport deficit, besides the characteristic mitochondrial impairment observed in these patients.
TEDE
BV UNIFESP: Teses e dissertações

The main topic of this thesis is a catalytic oxidation which belongs to a group of modern technologies for removing emission of CO and VOC from waste air. In the introduction of this thesis, the basic concepts are defined. Further the legislative requirements associated with VOC emissions, emission limits and conditions are summarized. Described destructive and non-destructive methods for removing VOCs from waste gases are also briefly described. Increased attention is paid to the catalytic oxidation as the main theme of the thesis. It was searched for industrial applications where the catalytic oxidation is used. Another chapter is devoted to the theoretical analysis of kinetics of catalytic oxidation reactions. Firstly, the basic types of reactors are described and also material balance and reaction rate for the isothermal and adiabatic reactor. In the experimental part results of performed kinetic measurements on a pilot unit for catalytic commonly used organic solvents (VOCs) using commercially available catalysts were summarized. Pre-exponential factors and activation energies for sprinkling catalysts EnviCat VOC-5565 and EnviCat 55068 for substances ethanol, toluene and acetone were determined. "Light-off" curves for these substances and methane were measured and on sprinkled catalyst EnviCat 55068 and on monolithic catalyst Purelyst PH-304.

Diese Arbeit befasst sich mit der Kinetik der Fehlfaltung und Aggregation von Proteinen. Anhand dreier Beispiele, der Phosphoglyceratkinase (PGK) aus Hefe, einer Variante von Barstar und des Prion-Proteins des Syrischen Hamsters (SHaPrP(90-232)) wurde insbesondere die Kinetik der Bildung von Amyloidfibrillen und deren kinetischer Vorläuferstrukturen mittels dynamischer und statischer Lichtstreuung, Circulardichroismus, Infrarotspektroskopie, Elektronenmikroskopie und teilweise analytischer Chromatographie untersucht. Die Kinetiken wurden mit Konzepten der Aggregationstheorie von Kolloiden und der chemischen Kinetik beschrieben. Die Modellierung der Kinetiken weist ausgehend von der monomeren PGK bei pH 2 und 190 mM NaCl auf eine zweistufige Reaktionskaskade, bestehend aus irreversiblen, bimolekularen Elementarschritten hin. Während der ersten Stufe wird ein engverteiltes Ensemble von Oligomeren mit einer mittleren Masse von 10 Monomeren und wesentlichen Anteilen an beta-Faltblattstrukturen gebildet. Die Protofibrillen entstehen durch die Vereinigung der strukturell polaren Oligomere, die durch die erste Reaktionsstufe bereitgestellt werden und als kritische Oligomere bezeichnet werden. Die gefundene Kopplung des Wachstums der intermediären Zustände und die Zunahme der beta-Faltblattstruktur kann innerhalb eines verallgemeinerten Diffusions-Kollisions-Modells interpretiert werden, bei dem die beta-Stränge durch intermolekulare Wechselwirkungen stabilisiert werden. Die Fehlfaltung und Aggregation des SHaPrP(90-232) bei pH 4.2 und 1 M GuHCl und geeigneten Zusätzen an Salz zeigt einen augenscheinlichen Zweizustandsübergang mit hoher Reaktionsordnung ( >2.5) zwischen dem monomeren, alpha-helikalen Ausgangszustand und einem beta-faltblattreichen, ringförmigen Oktamer. Die Progresskurven der Umwandlung der Sekundärstruktur lassen sich mit dem Zeitverlauf einer bimolekularen Reaktion anpassen. Das Oktamer bildet bei hohen eingesetzten Proteinkonzentrationen Multimere. Auf sehr langen Zeitskalen setzt die Bildung von Protofibrillen ein. Das kritische Oktamer stellt die Vorstufe der nachgeschalteten Wachstumsphänomene dar. Unter geeigneten Umgebungsbedingungen kann der nicht-nativ, partiell gefaltete Zustand von Barstar bei niedrigem pH (A-Zustand) in einem zweistufigen Prozess erst in Protofibrillen und anschlie"send in reife Amyloidfibrillen konvertiert werden. Zur Aktivierung der Konversion des oligomeren A-Zustandes (mittlere Masse von 16 Monomeren) sind moderate Ionenstärken ([NaCl]>0) und erhöhte Temperaturen (T>50°C) notwendig. Die Bildung der Protofibrillen ist unabhängig von der eingesetzten Proteinkonzentration. Bei Raumtemperatur und entsprechender Ionenstärke bilden sich amorphe Aggregate. Dagegen führt die Erhöhung der Temperatur in Abwesenheit von Salz zur Dissoziation des oligomeren A-Zustandes. Alle drei Proteine müssen zur Ausbildung protofibrillärer Strukturen und gegebenenfalls reifer Fibrillen oligomere Zustände mit partiell gefalteter Konformation einnehmen. Diese kritischen Oligomere sind langlebige Intermediate, die den Dreh- und Angelpunkt für die Bildung nachgeordneter Strukturen darstellen. Die Bildung von Amyloidfibrillen ist somit ein mehrstufiger hierarchischer Strukturbildungsprozess. Die in der Literatur bekannten Modelle der nukleierten Polymerisierung und der nukleierten Konformationskonversion werden dem höchstens in gewissen Teilaspekten gerecht. Die Annahme einer universellen Kinetik der Amyloidbildung kann im Lichte der Ergebnisse dieser Arbeit nicht aufrechterhalten werden. Dagegen scheinen die Zustände des kritischen Oligomers und der Protofibrille als Hierarchiestufen der Amyloidbildung generische Bestandteile des Prozesses zu sein. Die Kinetik der Bildung der verschiedenen Hierarchiestufen weist keine nennenswerten Gemeinsamkeiten zwischen den drei untersuchten Proteinen auf.
This thesis deals with the kinetics of misfolding and aggregation of proteins. The kinetics of amyloid formation and precursors of three proteins, phosphoglcerate kinase (PGK), a barstar variante and the Syrian hamster Prion protein (SHaPrP(90-232)) were investigated by the use of dynamic and static light scattering, infrared spectroscopy, circular dichroism, electron microscopy and in part by analytical chromatography. The kinetics were described with concepts from the theory of colloidal aggregation and chemical kinetics. The modelling of the kinetics starting from the monomeric PGK at pH 2 and 190 mM NaCl points to a two stage reaction cascade built up by irreversible, bimolecuar elementary reaction steps. During the first stage a narrow distributed ensemble of oligomeric states with an average mass of ten monomers and essentially ordered amounts of beta-sheet structure is built up. Protofibrils are formed by coalescence of the structural polar oligomers provided by the first stage which are termed critical oligomers. The found coupling between growth and acquisition of beta-sheet structure is interpreted in terms of a generalized diffusion-collision model, where stabilization takes place by intermolecular interactions. The misfolding and aggregation of SHaPrP(90-232) shows an apparent two-state transition between the initial monomeric, alpha-helical state and an beta-sheet rich, annular octamer with high reaction order (>2.5) at pH 4.2 and 1 M GuHCl with appropriate amounts of salt added. Progress curves monitoring the secondary structure transition can be fitted by the time-course of bimolecular reactions. The octamer forms multimers at high protein concentrations. Formation of protofibrils sets up on very long time-scales. The critical octamer is a precursor for all subsequent growth processes. The non-native, partially folded state of barstar at low pH (A-state) can be converted in a two-stage process first to protofibrils and then to mature amyloid fibrils under appropriate environmental conditions. Conversion of the oligomeric A-state (average mass of 16 monomers) can be activated by elevated temperatures (T>50°C) in the presence of moderate amounts of salt ([NaCl]>0). Formation of protofibrils is independent of protein concentration. Amorphous aggregates are formed at room temperature with sufficient amounts of salt added. In contrast elevated temperatures in absence of salt lead to dissociation of the oligomeric A-state. All three proteins have to populate an oligomeric, partially folded state to form protofibrils and eventually mature fibrils. These critical oligomers are long-lived intermediates which are the pivotal point from which all other structures arise. Formation of amyloid fibrils is a hierarchical assembly process where structures are built up by several stages. Models known from the literature, in particular nucleation polymerization and nucleated conformational conversion, only master partial aspects of amyloid formation. The wide-spread assumption of a universal kinetics of amyloid formation turns out to be unjustified. In contrast, the states of critical oligomer and protofibril seem to be generic parts of the hierarchical assembly process. Comparison of the kinetics of each hierarchical level amoung the three investigated proteins shows no considerable similarities.

Goldnanopartikel werden in der kolloidalen Katalyse als Modellsystem genutzt, um den Einfluss des Partikelgröße, der Partikelform und der Zusammensetzung in bimetallischen Systemen sowie der Ligandensphäre auf die katalytische Reduktion von 4-Nitrophenol zu 4-Aminophenol zu untersuchen. Goldnanopartikel eignen sich vor allem deshalb als Modellsystem, da sie in kurzer Zeit, in hohen Ausbeuten und mit definierten Eigenschaften hergestellt werden können. Es konnte erstmals nachgewiesen werden, dass Goldnanopartikel mit einem Durchmesser von 13 nm die höchste katalytische Umsetzungsrate bei der Reduktion von 4-Nitrophenolzu 4-Aminophenol besitzen. Im Zuge dieser Arbeit wird dieses Aktivitätsmaximum der Nanopartikel näher untersucht. Dazu werden drei Aspekte vorgestellt: die Abhängigkeit von der Goldnanopartikelform, die Abhängigkeit der Substratgröße und der Einfluss der Ligandensphäre auf die Katalyse. Überraschenderweise ist CTAB als oberflächenaktiver Ligand ein Co-Katalysator bei der Reduktion, während die Anwesenheit von Natriumcitrat die Reaktion verlangsamt. Es wurden Aspekte wie die Konzentration und die Größe der Goldnanopartikel in dem komplexen Wechselspiel der Aktivitäten des Katalysators und Co-Katalysators untersucht. Dies führte zu der beispielgebenden Erkenntnis, dass oberflächenaktive Liganden mit positiver Ladung und Stickstofffunktionen die Katalyse positiv beeinflussen. In einer weiteren Studie wurde der Reaktionsmechanismus der 6-Elektronenreduktion von 4-Nitrophenol zu 4-Aminophenol erforscht. Es konnte zum ersten Mal gezeigt werden, dass die Reduktion in zwei Teilschritten abläuft. N-Arylhydroxylamin ist als wichtiges Intermediat in der Lösung der Reduktion erstmals nachgewiesen worden. Drei kinetische Regime werden für die Reduktion von 4-Nitrophenol gefunden und geben einen Einblick in die Oberflächenreaktion von Nitroaromaten an Goldnanopartikeln.
Gold nanoparticles as model systems in colloidal catalysis are used to gain insights into the decisive parameters of the catalytic model reduction. Size, shape, composition of bimetallic systems, and ligand sphere are factors influencing the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride in the presence of gold nanoparticles. The increasing interest in gold nanoparticle catalysis is mainly due to their stability, their fast and high yield synthesis as well as their extraordinary diversity of the modes of preparation. This thesis is assigned to unravel the important parameters of gold nanoparticle catalysis. In the first part of the thesis, CTAB-stabilized gold nanoparticles were synthesized by applying the seeding-growth approach in order to gain information about the size dependence of the catalytic reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. Unexpectedly, CTAB-stabilized gold nanoparticles with a diameter of 13nm were most efficient in this complex system. In this context, molecular aspects such as shape, size of the substrate and ligand sphere were discussed as possible reasons for the enhanced activity for medium sized gold nanoparticles. Here, it was shown for the first time that the ligand sphere plays a crucial role in colloidal catalysis. Micellar catalysis with colloidal gold nanoparticles was performed by means of ligand exchange procedures. In addition, this thesis shows for the first time that intermediates can be unambiguously identified in the reaction solution with colloidal gold nanoparticles as catalysts. 4-N-hydroxylaminophenol was found to be the key intermediate in this system. In this context, three kinetic regimes which were crucial for the aromatic nitro reduction are found to cover the reaction kinetics. Thus, this thesis provides new insight into the catalytic process itself and leads to a better understanding of the catalytic activity of gold nanoparticles.

In the present dissertation the formation of microstructure, the kinetics of densification and the formation of surface layers developing during liquid phase sintering of silicon carbide are studied. The focus is on the additive systems Al2O3 plus Y2O3 and AlN plus Y2O3. Phase and especially liquid phase formation in both of the systems SiC, Al2O3 , Y2O3 and AlN, Al2O3 , Y2O3 are investigated in detail examining 12 espectively 17 different compositions per system. Melting temperatures have been determined by TG/DTA, in both systems for the first time. Phase composition of samples was analysed by the combination of XRD, SEM and EDX. In the system SiC, Al2O3 , Y2O3 the formation of the phases expected from the quasibinary Al2O3 , Y2O3 could be observed thus silicon carbide has to be in equilibrium with the oxide additives. The low solubility of SiC in the oxide melt, which was suggested by Hoffmann and Nader, could be confirmed. In the system AlN, Al2O3 , Y2O3 the formation of phases as stated by Medraj was confirmed, except for the dimension of the stability region of the γ- spinel and YAG which is wider in the present work. For the first time diffusion coefficients of the species Y3+ and Al3+ in the oxide melt formed by Al2O3 and Y2O3 at temperatures above 1825 ◦ C were determined. The values are in the order of 2 · 10−6 cm2 /s which results in a diffusion length of 14.1 μm for a diffusion time of one second. This allows the fast equilibration of Y and Al deficiencies. Kinetics of densification was modeled by kinetic field, master curve and thermokinetic method, based on detailed experimental investigation of the shrinkage during liquid phase sintering of SiC. It could be proved that the first 30 − 40 % of densification are controlled by solid phase reactions which accelerate particle rearrangement without presence of a liquid phase. During the remaining 60 − 70 % of densification a liquid is present, resulting in the predominance of mechanisms of liquid phase sintering. The models deliver activation energies in the range from 608 KJ/mol to 1668 kJ/mol and allow, within the scope of validity of each method the prediction of densification during liquid phase sintering of silicon carbide. When sintering silicon carbide with Al2O3 plus Y2O3 the formation of several surface layers, depending on atmosphere, maximum temperature, dwelling time and amount and composition of additives was observed. In nitrogen atmosphere with low partial pressures a surface layer consisting of AlN is forming whilst at high partial pressures SiAlON- polytypes occur. After sintering in Argon or Ar-CO- atmosphere three main types of surface layers are present. One consists of alumina, one contains only YAG and one shows highly porous, additive depleted regions. An explanation for the formation of the several surface layers could be given by the combination of the determined diffusion coefficients with the results achieved in the thermodynamics part. The results achieved in this work can be a contribution to the knowledge based design of the production process of liquid phase sintering of silicon carbide.

Atomlagenabscheidung (ALD, Atomic Layer Deposition) ist als präzise Technik zur Abscheidung dünner Schichten bekannt. Mittels wechselweisen Einleitens von Precursorgasen in einen Reaktor erzeugt der Prozess auch auf strukturierten Substraten gleichmäßige dünne Schichten. Durch die selbstsättigende Natur der zu Grunde liegenden Reaktionen sind sowohl die Wachstumsrate als auch die Zusammensetzung wohldefiniert, weshalb sich Atomlagenabscheidung beispielsweise zur Herstellung nanoskopischer Bauelemente im Bereich der Mikroelektronik eignet. Obwohl Aluminiumoxid vermehrt Aufmerksamkeit für seine hohe Bandlücke (~9 eV) sowie die relativ hohe Dielektrizitätskonstante (k ~ 9) geerntet hat, ist oftmals trotz vielseitiger Untersuchungen der anwendbaren Precursorpaare nur wenig über die strukturellen Eigenschaften sowie die Wachstumskriterien der resultierenden Schichten bekannt. In dieser Arbeit wurde eine kombinierte Simulationsmethode entwickelt, mit der sich Atomlagenabscheidung mittels elementarer Reaktionen auf beliebig strukturierten Substraten simulieren lässt. Molekulardynamische Berechnungen ermöglichen dabei atomare Genauigkeit, wohingegen die Ankunft der individuellen Precursoratome durch Kinetic Monte Carlo-Methoden dargestellt werden. Diese Aufteilung erlaubt die Kopplung der molekulardynamischen Präzision mit den Größenordnungen einer KMC-Simulation, welche prinzipiell die Betrachtung von Milliarden von Atomen zulässt. Durch asynchrone Parallelisierung mit bis zu tausenden Arbeiterprozessen wird zudem die Effizienz gegenüber einer herkömmlichen Molekulardynamiksimulation ausreichend erhöht, um binnen weniger Stunden mehrere Abscheidungszyklen nahezu unabhängig von der Größe des betrachteten Raumes, welche im Bereich von Quadratmikrometern liegen kann, zu simulieren. Zur abschließenden Validierung des Modells und seiner Implementierung werden einerseits Versuche einfacher Schichtwachstumsprozesse unternommen, andererseits wird die Atomlagenabscheidung des wohluntersuchten Precursorpaares Trimethylaluminium (TMA, Al(CH3)3) und Wasser simuliert und die resultierende Schicht auf Übereinstimmung mit bestehenden Daten geprüft.

Atomlagenabscheidung (ALD, Atomic Layer Deposition) ist als präzise Technik zur Abscheidung dünner Schichten bekannt. Mittels wechselweisen Einleitens von Precursorgasen in einen Reaktor erzeugt der Prozess auch auf strukturierten Substraten gleichmäßige dünne Schichten. Durch die selbstsättigende Natur der zu Grunde liegenden Reaktionen sind sowohl die Wachstumsrate als auch die Zusammensetzung wohldefiniert, weshalb sich Atomlagenabscheidung beispielsweise zur Herstellung nanoskopischer Bauelemente im Bereich der Mikroelektronik eignet. Obwohl Aluminiumoxid vermehrt Aufmerksamkeit für seine hohe Bandlücke (~9 eV) sowie die relativ hohe Dielektrizitätskonstante (k ~ 9) geerntet hat, ist oftmals trotz vielseitiger Untersuchungen der anwendbaren Precursorpaare nur wenig über die strukturellen Eigenschaften sowie die Wachstumskriterien der resultierenden Schichten bekannt. In dieser Arbeit wurde eine kombinierte Simulationsmethode entwickelt, mit der sich Atomlagenabscheidung mittels elementarer Reaktionen auf beliebig strukturierten Substraten simulieren lässt. Molekulardynamische Berechnungen ermöglichen dabei atomare Genauigkeit, wohingegen die Ankunft der individuellen Precursoratome durch Kinetic Monte Carlo-Methoden dargestellt werden. Diese Aufteilung erlaubt die Kopplung der molekulardynamischen Präzision mit den Größenordnungen einer KMC-Simulation, welche prinzipiell die Betrachtung von Milliarden von Atomen zulässt. Durch asynchrone Parallelisierung mit bis zu tausenden Arbeiterprozessen wird zudem die Effizienz gegenüber einer herkömmlichen Molekulardynamiksimulation ausreichend erhöht, um binnen weniger Stunden mehrere Abscheidungszyklen nahezu unabhängig von der Größe des betrachteten Raumes, welche im Bereich von Quadratmikrometern liegen kann, zu simulieren. Zur abschließenden Validierung des Modells und seiner Implementierung werden einerseits Versuche einfacher Schichtwachstumsprozesse unternommen, andererseits wird die Atomlagenabscheidung des wohluntersuchten Precursorpaares Trimethylaluminium (TMA, Al(CH3)3) und Wasser simuliert und die resultierende Schicht auf Übereinstimmung mit bestehenden Daten geprüft.:1 Einführung 1.1 Anwendungen von Atomlagenabscheidung 1.2 Aktueller Stand 1.2.1 Experimentelle Untersuchungen 1.2.2 Kinetic Monte Carlo-Simulationen von Dwivedi 1.2.3 Kinetic Monte Carlo-Simulationen von Mazaleyrat 1.2.4 Molekulardynamik-Simulationen 1.2.5 Dichtefunktionaltheoretische Rechnungen von Musgrave 1.3 Motivation 2 Grundlagen 2.1 Atomlagenabscheidung 2.1.1 Einführung zur Atomlagenabscheidung 2.1.2 ALD von Metalloxiden 2.1.3 ALD von Al2O3 2.2 Kinetic Monte Carlo Methoden 2.2.1 KMC-Formalismus 2.2.2 KMC-Algorithmen 2.3 Molekulardynamik 2.3.1 Grundlagen 2.3.2 Methoden zur Ensembledarstellung 2.3.3 Potentialarten 2.3.4 Numerische Optimierungen 3 Kombiniertes Modell 3.1 Verwendetes Kinetic Monte Carlo-Modell 3.2 Kombiniertes Modell 3.2.1 Abscheidungszyklus 3.2.2 Simulationsraum 3.2.3 Ereignisse 3.2.4 Parallelisierungsmethode 3.2.5 Abhängigkeitsgraph 4 Implementierung 4.1 Existierende Software 4.1.1 LAMMPS 4.1.2 SPPARKS 4.1.3 Sonstige Software 4.2 LibKMC 4.2.1 Modularisierung 4.2.2 Abhängigkeiten 4.3 Implementierung des kombinierten Modells 4.3.1 Vorstellung der Software 4.3.2 Einbindung von LibKMC 4.3.3 Einbindung von LAMMPS 4.3.4 Host-Worker-System 4.3.5 Substratgenerierung 5 Validierung 5.1 Validierung des kombinierten Modelles 5.1.1 Wachstumskriterium 5.1.2 Sättigungskriterium 5.1.3 Parallelisierungseffizienz 5.2 Untersuchungen von Al2O3 5.2.1 Potentialuntersuchungen 5.2.2 Schichtwachstumseigenschaften 5.2.3 Strukturanalyse 6 Zusammenfassung und Ausblick Literaturverzeichnis Danksagung

A análise das variáveis associadas à fadiga muscular durante protocolos de ciclismo até a exaustão (incremental e carga constante), ou mesmo simulados (contrarrelógio), e suas implicações em parâmetros cinéticos e cinemáticos, têm sido descritas na literatura em modelos experimentais. Alterações encontradas nas articulações do quadril, joelho e tornozelo, associadas a mudanças no direcionamento das forças aplicadas ao pedal (melhora da técnica de pedalada) durante testes de ciclismo incrementais e/ou constantes, parecem estar relacionados a estratégias musculares intrínsecas para manutenção do trabalho e postergar os efeitos da fadiga. Entretanto, evidências suportam que a aplicação de Laserterapia de Baixa Potência (LBP) reduz os efeitos da fadiga muscular sobre o desempenho, principalmente em modalidades esportivas com um grande componente aeróbico, tal como o ciclismo. Entretanto, ainda não está claro na literatura qual a dosagem ideal de LBP a ser utilizada nessas atividades. Portanto, o objetivo deste estudo foi investigar os efeitos de diferentes dosagens de LBP sobre o desempenho em teste de tempo de exaustão em ciclistas. Além disso, foi analisado os efeitos do LBP sobre o conteúdo de frequências dos sinais de EMG e a cinética de VO2 durante os testes de exaustão. Vinte ciclistas competitivos do sexo masculino participaram de um estudo, randomizado, duplocego e placebo-controlado. Os atletas realizaram teste incremental de ciclismo até a exaustão (dia 1) para determinar o consumo máximo de oxigênio (VO2MÁX) e a potência máxima (POMÁX), seguido de outros quatro testes até a exaustão (dias 2 a 5) na POMÁX do teste incremental. Antes de cada teste de exaustão, diferentes dosagens de LBP (3, 6 e 9 J/diodo, ou 135, 270 e 405 J/coxa, respectivamente) ou placebo. Aumento do desempenho nos testes de exaustão foi observado com a LBP-3J (~22 s; p < 0,01), LBP-6J (~13 s; p = 0,03) e LBP- 9J (~13 s; p = 0,02), comparado com o placebo (149 ± 23 s). Embora LBP-6J e LBP-9J não aumentaram a ativação muscular em comparação com o placebo, a LBP-3J, aumentou a ativação das bandas de alta frequência em comparação com o placebo no final do teste de exaustão, em ambos os membros inferiores (p ≤ 0,03). Os resultados na cinética de VO2, resultaram e redução do constante de tempo (Tau) e déficit de O2 com a aplicação de LBP comparado ao placebo (p < 0,05). Não foram encontradas diferenças (p > 0,05) entre as condições experimentais para amplitude de VO2 e tempo de atraso do VO2. Em conclusão, nosso estudo demonstrou que a fototerapia pode ser um agente ergogênico eficaz para aumentar o desempenho de ciclistas (independente da dose utilizada), e isto se deve ao aumento da ativação das bandas de alta frequência (LBP-3J), bem como da redução do Tau e déficit de O2 (LBP-3 6 e 9J), durante testes máximos de ciclismo até a exaustão.
The analysis of muscle fatigue variables during cycling protocols to exhaustion (incremental and constant load) or simulated (time trial), and its implications on kinetic and kinematic parameters, has been described in the literature for experimental models. Changes in hip, knee and ankle joints (such as increased range of motion and reduced ankle contribution to the total joint torque), associated with changes in the direction of the forces applied to the pedal (improved pedaling technique) during cycling tests, seems to be related to strategies for maintaining muscle work in order to postpone fatigue effects. However, evidences supports that application of low-level laser therapy (LLLT) minimizes fatigue effects on muscle performance. However, the ideal LLLT dosage to improve athletes’ performance during sports activities, such as cycling, is still unclear. Therefore, the goal of this study was to investigate the effects of different LLLT dosages on cyclists’ performance during a time-to-exhaustion test. In addition, we looked at the effects of LLLT on the frequency content of the EMG signals and kinetics of VO2 to assess fatigue mechanisms. Twenty male competitive cyclists participated in a crossover, randomized, double-blind and placebo controlled trial. They performed an incremental cycling test to exhaustion (day 1) determine maximal oxygen output (VO2MAX) and maximal power output (POMAX) followed by four time-to-exhaustion tests (days 2 to 5) at their individual POMAX. Before each time to exhaustion test, different LLLT dosages (3, 6 and 9 J/diode; or 135, 270 and 405 J/thigh, respectively) or placebo were applied at the quadriceps muscle bilaterally. Power output and muscle activation from both lower limbs were acquired throughout the tests. Increased performance at the exhaustion tests was observed with the LLLT-3J (~22 s; p < 0.01), LLLT-6J (~13 s; p = 0.03) and LLLT-9J (~13 s; p = 0.02) compared to placebo (149 ± 23 s). Although LLLT-6J and LLLT-9J did not show significant differences in muscle activation compared to placebo, LLLT-3J led to an increased high frequency content compared to placebo in both limbs at the end of the exhaustion test (p ≤ 0.03). The results in kinetics VO2, resulting in reduction of time constant (Tau) and deficit O2 with LLLT applications compared to the placebo condition (p < 0.05). No differences (p > 0.05) were found between the experimental conditions for VO2 amplitude and VO2 delay time. In conclusion, this study has shown that the phototherapy can be an effective ergogenic agent to increase cycling performance (regardless of the dose used), and this is due to increased activation of the high frequency bands (LLLT-3J) as well as the reduction of Tau and deficit of O2 (LLLT-3, 6 and 9J), during maximum cycling exhaustion test.