by Lo Ming Yip. / "July 1998." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 208-247). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstract in Chinese.

A hipertensão arterial é uma doença que aflinge mais de um quarto da população adulta mundial e mais da metade da população idosa. Ela é o principal fator de risco para doenças cerebrovasculares e o segundo fator de risco, após idade, para os acidentes vasculares cerebrais (AVC) hemorrágico e isquêmico. É também a principal causa de declínio cognitivo e demência, incluindo a doença de Alzheimer. A hipertensão causa remodelamento vascular e modifica os mecanismos de regulação do fluxo sangüíneo cerebral, incluindo a hiperemia funcional, a autoregulação cerebrovascular e a regulação endotelial. Portanto, pesquisas contínuas sobre os efeitos da hipertensão na função cerebrovascular são cruciais para o desenvolvimento de terapias preventivas que objetivam minimizar os riscos de desenvolvimento de doenças cerebrovasculares. No presente estudo, a perfusão cerebral de um importante modelo experimental de hipertensão, o rato SHR (do inglês spontaneously hypertensive rat), foi avaliada utilizando as técnicas de arterial spin labeling (ASL), que permitem a quantificação não-invasiva da perfusão. Utilizando o método de ASL contínua, o fluxo sangüíneo cerebral foi quantificado para todo o cérebro do rato sob condições de normocapnia e hipercapnia. Resistência cerebrovascular aumentada e reatividade vascular ao CO2 reduzida foram observadas em SHR adultos, confirmando que a hipertensão leva à redução progressiva da capacidade de dilatação da vasculatura cerebral. A técnica de ASL dinâmica permitiu medir o fluxo sangüíneo cerebral funcional evocado por estimulação somatosensorial. Além de apresentarem resposta hemodinâmica positiva à estimulação, os ratos hipertensos também apresentaram resposta hemodinâmica negativa em áreas circundantes àquelas ativadas positivamente. Foi mostrado que esse resultado está relacionado com um efeito puramente hemodinâmico causado pela pressão arterial elevada e pela reserva vascular alterada do SHR. Experimentos farmacológicos mostraram diferenças na modulação do acoplamento neurovascular de SHR quando comparado com rato normotenso. Além disso, SHR submetidos à oclusão temporária da artéria cerebral média apresentaram maior volume da lesão isquêmica e do edema cerebral, redução severa da massa corporal e déficits neurológicos piores do que ratos normotensos. Esses resultados estão relacionados à autoregulação cerebral alterada e ao desenvolvimento prejudicado da circulação colateral em SHR. Em suma, os achados do presente estudo mostraram que a hipertensão resulta em reserva vascular prejudicada, acoplamento neurovascular alterado e piores conseqüências a um AVC isquêmico. / Hypertension is a disease that afflicts more than a quarter of the general population and more than half of the elderly population. It is the most important modifiable risk factor for cerebrovascular diseases and the second most important risk factor, after age, for hemorrhagic and ischemic stroke. It is a leading cause of cognitive decline and dementia, including the Alzheimer\'s disease. Hypertension causes vascular remodeling and modifies the intricate mechanisms of cerebral blood flow (CBF) regulation, including functional hyperemia, cerebrovascular autoregulation, and endothelial regulation. For all of the above, continued research on the effects of hypertension on cerebrovascular function is a crucial step in the design of preventive therapies aimed at minimizing the risk of development of cerebrovascular disease. In the present work, cerebral perfusion of an important experimental model of hypertension, the spontaneously hypertensive rat (SHR), was evaluated using the arterial spin labeling (ASL) techniques, which allow non-invasive quantification of perfusion. Using continuous ASL, CBF was quantified for the whole rat brain under normocapnic and hypercapnic conditions. Increased cerebrovascular resistance and decreased vascular reactivity to CO2 were observed in adult SHR, confirming that hypertension leads to reduced compliance of the cerebral vasculature. The dynamic ASL technique allowed the measurement of functional CBF evoked by somatosensorial stimulation. Hypertensive rats not only showed positive hemodynamic response to stimulation, but also negative hemodynamic response in areas surrounding the positively activated areas. It was shown to be related to a purely hemodynamic effect caused by high blood pressure and impaired vascular reserve of the SHR. Pharmacological experiments showed differences on modulation of the neurovascular coupling in SHR when compared to normotensive rats. Moreover, hypertensive rats subjected to temporary middle cerebral artery occlusion had larger ischemic lesion volume and brain edema, severe decrease in body weight and worse neurological deficits, when compared to normotensive rats. These results are related to the altered cerebral autoregulation and impaired collateral circulation development in SHR. Taken together, the findings of the present work show that hypertension results in impaired vascular reserve, which is related to altered neurovascular coupling and worse stroke outcome.

INTRODUÇÃO: O envolvimento vascular tem sido reconhecido como uma importante causa de morbidade e mortalidade na Doença de Behçet (DB), mas a importância de métodos não-invasivos em identificar lesões vasculares precoces ainda não foi bem estabelecida. OBJETIVO: Avaliar as propriedades estruturais e funcionais dos vasos na DB utilizando a medida da velocidade de onda de pulso (VOP) carótido-femoral e a avaliação de carótida pelo echo-tracking system. MÉTODOS: Pacientes com DB sem fatores de risco cardiovasculares tradicionais (hipertensão, diabetes, tabagismo e obesidade) foram selecionados consecutivamente. Todos os pacientes com DB realizaram aferição de VOP e ultrasom de carótida. Pacientes com DB foram divididos de acordo com a presença ou não de envolvimento sistêmico (vascular e/ou ocular e/ou sistema nervoso central) e vascular. Controles saudáveis, pareados para sexo e idade, com os mesmos critérios de exclusão foram selecionados. RESULTADOS: Os vinte e três pacientes com DB (11 homens, média de idade de 35,0±7,6 anos), tiveram níveis significativamente maiores de VOP, comparados ao grupo controle (8,4±1,1 vs. 7,5±1,4 m/s, p=0,017). A espessura íntima-média (594,8±138,6 vs. 561,0±134,2 m, p=0,371), o diâmetro diastólico (6383,7±960,4 vs. 6447,6±1159,7 m, p=0,840), a distensão (401,9±117,7 vs. 337,9±175,3 m, p=0,225) e a distensão relativa (6,2±2,8 vs. 5,4±2,4 m, p=0,293) da artéria carótida foram semelhantes entre os grupos. O grupo com doença sistêmica teve níveis significativamente maiores de VOP (8,7±1,2 vs. 7,8±0,7 m/s, p=0,036) comparado àqueles com manifestação exclusivamente mucocutânea. Pacientes com DB e acometimento vascular tiveram os parâmetros de VOP e echotracking similares aos pacientes sem acometimento vascular, mas apresentaram níveis maiores de colesterol total e LDL (p=0,019 e p=0,012, respectivamente). Uma análise de regressão linear multivariada identificou o nível de triglicerídeos como o mais importante fator associado ao aumento dos níveis de VOP (p=0,001) na DB. CONCLUSÕES: A VOP é mais útil do que o ultra-som de carótida para detectar dano vascular em pacientes com DB e enfatizamos o papel da própria doença em promover essas alterações. Os achados reforçam a necessidade de um controle rigoroso de todos os fatores de risco cardiovasculares na DB, particularmente lipoproteínas / INTRODUCTION: Vascular involvement has been recognized as an important cause of morbidity and mortality in Behçets disease (BD) but the role of noninvasive methods in identify early vascular lesions is not established. OBJECTIVE: To evaluate structural and functional properties of vessels in BD using carotid-femoral pulse wave velocity (PWV) and echo-tracking system. METHODS: BD patients without traditional cardiovascular risk factors (hypertension, diabetes, smoking, and obesity) were consecutively selected. All BD patients performed PWV and carotid ultrasound. BD patients were divided according to the presence or not of systemic (vascular and/or ocular and/or central nervous system involvement) and vascular involvement. Healthy controls age- and sex-matched with the same exclusion criteria were selected. RESULTS: The twenty-three BD patients (11 male, mean age 35.0±7.6 years), had a significantly higher PWV levels compared to control group (8.4±1.1 vs. 7.5±1.4 m/s, p=0.017). Intima-media thickness (594.8±138.6 vs. 561.0±134.2 m, p=0.371), diastolic diameter (6383.7±960.4 vs. 6447.6±1159.7 m, p=0.840), distension (401.9±117.7 vs. 337.9±175.3 m, p=0.225), and relative distension (6.2±2.8 vs. 5.4±2.4 m, p=0.293) were similar in both groups. Multivariate linear regression analysis identified triglycerides as the most important factor in increasing PWV levels (p=0.001) in BD. Systemic disease group had significant higher levels of PWV (8.7±1.2 vs. 7.8±0.7 m/s, p=0.036) compared to those with exclusive mucocutaneous manifestations. BD patients with vascular involvement had similar PWV and echo-tracking parameters compared to those without, but had higher total and LDL cholesterol levels (p=0.019 and p=0.012, respectively). CONCLUSIONS: PWV is more useful than carotid ultrasound in detecting structural and functional vascular damage in BD and emphasize the role of the disease itself in promoting these alterations. Our findings also reinforce the need of a rigorous control of all risk factors in BD, particularly lipoproteins

Objetivo: Avaliar o efeito da compressão elástica e enfaixamento compressivo funcional associados à cinesioterapia sobre o fluxo sanguíneo do membro superior com linfedema secundário ao tratamento do câncer de mama. Métodos: Trata-se de ensaio clínico randomizado cego crossover, com período washout de sete dias entre os tratamentos. Foram avaliadas 20 mulheres com idade média de 66.85 anos (DP = 11.76), submetidas a três tipos de procedimentos terapêuticos aplicados aleatoriamente mediante sorteio: cinesioterapia (C), cinesioterapia + enfaixamento compressivo funcional (ECF), cinesioterapia + compressão elástica (CE). O fluxo sanguíneo, incluindo velocidade média e máxima, foi avaliado por meio de ultrassom Doppler antes e após procedimento terapêutico, nos tempos 0, 15, 30 minutos. Foi utilizado análise de variância (ANOVA) de medidas repetidas seguido do teste de Bonferroni, considerado um nível de significância de 5%. Resultados: Os grupos CE e ECF apresentaram incremento significativo da velocidade média do fluxo sanguíneo das artérias e veias axilar e braquial, quando comparados ao grupo que recebeu apenas cinesioterapia (C). Quando realizadas as comparações entre os grupos CE e ECF, não foi observada diferença significativa (p>0.05). Foi observada interação grupo-versus-tempo para a artéria (F=7.033, p<0.001) e veia axilar (F=5.524, p<0.001), e para artéria (F= 11.195, p<0.001) e veia braquial (F=10.521, p<0.001), sendo os grupos CE e ECF com incremento circulatório mais significativo (p<0.05). Com relação à velocidade máxima, foi observada significativa interação grupo-versus-tempo para a artéria braquial (F=2.492, p=0.029). Conclusão: A CE e o ECF associados à C produzem incremento do fluxo sanguíneo do membro superior com linfedema. / Objective: To evaluate the effect of elastic compression, functional compressive bandaging and kinesiotherapy on blood flow of the upper limb with lymphedema secondary to the treatment of breast cancer. Methods: This was a randomized blind crossover clinical trial with washout period of seven days between treatments. We evaluated 20 women with a mean age of 66.85 years (standard deviation = 11.76), submitted to three types of therapeutic procedures randomly applied by lot: kinesiotherapy, kinesiotherapy + functional compressive bandaging (FCB), kinesiotherapy + elastic compression (EC). Blood flow, including mean and maximum velocity, was assessed by Doppler ultrasound before and after therapeutic procedure (immediately after, 15 and 30 minutes). We used 2-way analysis of variance for repeated measures followed by Bonferroni\'s test, considering a significance level of 5%. Results: The EC and FCB groups showed significant increase in the mean velocity of blood flow of the axillary and brachial arteries and veins when compared to the group that received only kinesiotherapy (p<0.05). When made comparisons between the EC and FCB groups, there was no significant difference (p>0.05). Regarding to the maximum velocity the EC and FCB groups showed greater increase of the maximum velocity of blood flow in the brachial artery (p<0.05) when compared to the group that received only kinesiotherapy, but no difference between them (p>0.05). Conclusion: The elastic compression and functional compressive bandaging associated to kinesiotherapy produce increased blood flow of upper limb lymphedema

INTRODUÇÃO: O envolvimento vascular tem sido reconhecido como uma importante causa de morbidade e mortalidade na Doença de Behçet (DB), mas a importância de métodos não-invasivos em identificar lesões vasculares precoces ainda não foi bem estabelecida. OBJETIVO: Avaliar as propriedades estruturais e funcionais dos vasos na DB utilizando a medida da velocidade de onda de pulso (VOP) carótido-femoral e a avaliação de carótida pelo echo-tracking system. MÉTODOS: Pacientes com DB sem fatores de risco cardiovasculares tradicionais (hipertensão, diabetes, tabagismo e obesidade) foram selecionados consecutivamente. Todos os pacientes com DB realizaram aferição de VOP e ultrasom de carótida. Pacientes com DB foram divididos de acordo com a presença ou não de envolvimento sistêmico (vascular e/ou ocular e/ou sistema nervoso central) e vascular. Controles saudáveis, pareados para sexo e idade, com os mesmos critérios de exclusão foram selecionados. RESULTADOS: Os vinte e três pacientes com DB (11 homens, média de idade de 35,0±7,6 anos), tiveram níveis significativamente maiores de VOP, comparados ao grupo controle (8,4±1,1 vs. 7,5±1,4 m/s, p=0,017). A espessura íntima-média (594,8±138,6 vs. 561,0±134,2 m, p=0,371), o diâmetro diastólico (6383,7±960,4 vs. 6447,6±1159,7 m, p=0,840), a distensão (401,9±117,7 vs. 337,9±175,3 m, p=0,225) e a distensão relativa (6,2±2,8 vs. 5,4±2,4 m, p=0,293) da artéria carótida foram semelhantes entre os grupos. O grupo com doença sistêmica teve níveis significativamente maiores de VOP (8,7±1,2 vs. 7,8±0,7 m/s, p=0,036) comparado àqueles com manifestação exclusivamente mucocutânea. Pacientes com DB e acometimento vascular tiveram os parâmetros de VOP e echotracking similares aos pacientes sem acometimento vascular, mas apresentaram níveis maiores de colesterol total e LDL (p=0,019 e p=0,012, respectivamente). Uma análise de regressão linear multivariada identificou o nível de triglicerídeos como o mais importante fator associado ao aumento dos níveis de VOP (p=0,001) na DB. CONCLUSÕES: A VOP é mais útil do que o ultra-som de carótida para detectar dano vascular em pacientes com DB e enfatizamos o papel da própria doença em promover essas alterações. Os achados reforçam a necessidade de um controle rigoroso de todos os fatores de risco cardiovasculares na DB, particularmente lipoproteínas / INTRODUCTION: Vascular involvement has been recognized as an important cause of morbidity and mortality in Behçets disease (BD) but the role of noninvasive methods in identify early vascular lesions is not established. OBJECTIVE: To evaluate structural and functional properties of vessels in BD using carotid-femoral pulse wave velocity (PWV) and echo-tracking system. METHODS: BD patients without traditional cardiovascular risk factors (hypertension, diabetes, smoking, and obesity) were consecutively selected. All BD patients performed PWV and carotid ultrasound. BD patients were divided according to the presence or not of systemic (vascular and/or ocular and/or central nervous system involvement) and vascular involvement. Healthy controls age- and sex-matched with the same exclusion criteria were selected. RESULTS: The twenty-three BD patients (11 male, mean age 35.0±7.6 years), had a significantly higher PWV levels compared to control group (8.4±1.1 vs. 7.5±1.4 m/s, p=0.017). Intima-media thickness (594.8±138.6 vs. 561.0±134.2 m, p=0.371), diastolic diameter (6383.7±960.4 vs. 6447.6±1159.7 m, p=0.840), distension (401.9±117.7 vs. 337.9±175.3 m, p=0.225), and relative distension (6.2±2.8 vs. 5.4±2.4 m, p=0.293) were similar in both groups. Multivariate linear regression analysis identified triglycerides as the most important factor in increasing PWV levels (p=0.001) in BD. Systemic disease group had significant higher levels of PWV (8.7±1.2 vs. 7.8±0.7 m/s, p=0.036) compared to those with exclusive mucocutaneous manifestations. BD patients with vascular involvement had similar PWV and echo-tracking parameters compared to those without, but had higher total and LDL cholesterol levels (p=0.019 and p=0.012, respectively). CONCLUSIONS: PWV is more useful than carotid ultrasound in detecting structural and functional vascular damage in BD and emphasize the role of the disease itself in promoting these alterations. Our findings also reinforce the need of a rigorous control of all risk factors in BD, particularly lipoproteins

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-26T17:30:38Z No. of bitstreams: 1 ItamaraFranca.pdf: 611104 bytes, checksum: 4827358f1120e6b66cf862bb0635763f (MD5) / Made available in DSpace on 2017-06-26T17:30:38Z (GMT). No. of bitstreams: 1 ItamaraFranca.pdf: 611104 bytes, checksum: 4827358f1120e6b66cf862bb0635763f (MD5) Previous issue date: 2016-08-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / The objective of this study was to evaluate the effect of the reproductive tract scoring (RTS) on follicular dynamics and utero-ovarian doppleflowmetry in Bos indicus heifers of nelore. Were used 34 females cattle the females were classified into three categories, according to RTS: RTS 1 (diameter of the uterine horns <15 mm and diameter of follicles <8 mm; RTS 2 (diameter of the uterine horns ≥ 15mm and follicles ≥8 mm; RTS3 (diameter of the uterine horns ≥15mm and presence of CL). Then, were synchronized with progestin/estradiol-based protocol, plus prostaglandin, for padronization of the follicular and luteal status. The monitoring of the follicular dynamics and utero-ovarian flowmetry was performed by B-mode, color doppler and spectral doppler ultrasonography during three times: Day 0 (D0; ear implant insertion); Day 10 (D10, detection preovulatory follicles) and; Day 18 (D18; determination of ovulation by detection of corpora lutea). The uterine diameter showed a significant increase between D0 and D10 in both categories. The ovulation rate was higher in the RTS 3 (P<0.05). There was no effect of RTS nor of examination day on vascularity and number of pixels of the the ovary (P>0.05). In the follicular dominance phase (D10), the higher vascularization occurred in RTS2, followed by RTS 1 and 3, respectively (P<0.05). The uterine PI and RI were not affected by RTS nor by the examination day (P>0.05). However, when these same rates were evaluated in the ovary, the RI showed significant effect of RTS and RTS x day (P=0.02). Progesterone concentrations at the beginning of trial (D0) were higher in the RTS 3 (P<0.05) and estradiol did not differ significantly between categories (P<0.05) at day of follicular dominance (D10). It was concluded that RTS influences the follicular growth, ovulation rate and vascularization of the uterine horns. / Objetivou-se com este estudo avaliar o efeito do escore do trato reprodutivo (ETR) na dinâmica folicular e dopplerfluxometria útero-ovariana em novilhas da raça nelore (Bos indicus). Utilizou-se 34 fêmeas que foram classificadas em três categorias, de acordo com o ETR: ETR 1 (novilhas com diâmetro dos cornos uterinos <15mm e com folículos de diâmetro <8mm; ETR2 (novilhas com diâmetro dos cornos uterinos ≥ 15mm e folículos ≥8 mm e; ETR3 (novilhas com diâmetro dos cornos uterinos ≥15mm e presença de corpo lúteo (CL). Em seguida, foram sincronizadas com protocolo à base de progestágeno/estradiol/prostaglandina para padronização do status folicular e luteínico. O acompanhamento da dinâmica folicular e fluxometria útero-ovariana foram realizadas por ultrassonografia (US) nos modos bidimensional, color doppler e espectral doppler em 3 períodos pré-determinados: Dia 0 (D0; inserção do implante auricular); Dia 10 (D10; detecção folículo pré-ovulatório) e; Dia 18 (D18; determinação da ovulação por meio da detecção do corpo lúteo). O diâmetro uterino apresentou um aumento significativo entre o D0 e D10 em ambas as categorias. A taxa de ovulação foi maior no ETR 3 (P<0,05). Não houve efeito de ETR ou dia de exame na área de vascularização e número de pixels no ovário (P>0,05). Na fase de dominância folicular (D10), a maior perfusão ocorreu no ETR2, seguida pelos ETRs 1 e 3, respectivamente (P<0,05). O IP e o IR uterinos não foram influenciados pelo ETR nem pelo dia do exame (P>0,05). Entretanto, quando estes mesmos índices foram avaliados no ovário, nota-se que o RI manifestou efeito significativo do ETR e interação ETR x dia do exame (P=0,02). As concentrações plasmáticas de progesterona ao início do experimento (D0) foram maiores no ETR 3 (P<0,05) e o estradiol não diferiu significativamente entre as categorias (P<0,05) na fase de dominância folicular sincronizada (D10). Conclui-se que o ETR influencia no crescimento folicular, na taxa de ovulação e na vascularização dos cornos uterinos.

Functional magnetic resonance imaging (fMRI) can be used to track neural activation in the brain during functional activities. The purpose of this study was to investigate brain neural responses to blood flow restricted (BFR) versus control handgrip exercise. Using a randomized crossover design, 25 subjects (12 males, 13 females) completed handgrip exercises during two conditions: BFR vs. control. To familiarize participants with the exercise conditions, one week prior to MRI scanning participants completed each exercise condition once on separate days, with 72 hours between days. The following week fMRI scans were performed at the same time of day, separated by 72 hours. The exercise protocol consisted of five 30-second sets of squeezing a nonmetallic handgrip exerciser (a reported 13.6 kg resistance), doing as many repetitions as possible, with 20-second rest intervals between sets. We saw a significant main effect of exercise condition (BFR versus control) between premotor dorsal (PMd)(F = 5.71, p = 0.022), premotor ventral (PMv)(F = 8.21, p = 0.007), and right ventral striatum (VS_R)(F = 7.36, p = 0.01). When considering anatomical regions of interest, we did not find significant differences between exercise conditions in bilateral S1 (p > 0.82), primary motor cortex (M1)(p > 0.33), supplementary motor area (SMA)(p > 0.66), cerebellum (CB)(p > 0.70), insular cortex (INS)(p > 0.45), anterior cingulate cortex (ACC)(p > 0.24), or thalamus (TH)(p > 0.66). Bilateral ACC (ACC_B), right middle frontal gyrus (MFG_R), and the right primary sensory cortex (S1_R) showed significant linear trends (p = 0.001) over the five exercise sets. Finally, the S1_R, left primary sensory cortex (S1_L), and the right anterior cingulate cortex (ACC_R) showed a main effect of set (p < 0.02). These data demonstrate that acute training with BFR during handgrip exercise results in different neural activation patterns in select areas of the brain, compared to a control. These results show that while completing less work with BFR exercise, subjects can achieve a similar amount of brain neural activation as with a higher-volume exercise. Brain neural activation is important to overall patient health and these findings may be important for prescribing training with BFR in clinical and applied research settings.

Left coronary blood flow (LCBF), left ventricular oxygen, extraction [(a-v)O₂ ], and myocardial oxygen consumption (MVO₂) were monitored in 10 dogs. HR was paced at 120 bpm and then increased to 180 bpm to elicit a hyperemic response (ΔLCBF). During the hyperemia, the vaso-dilatory response to exogenous adenosine (F_AD) was tested. Twenty min. after injection of aminophylline (100 mg/i.v.), HR was again increased. F_AD was again tested. The pacing-induced increase in MVO₂ (ΔMVO₂) was not affected by aminophylline (P>0.05). However, the slope ΔLCBF/ΔMVO₂ was decreased, and the slope (a-v)O₂ /ΔMVO₂ was increased. F_AD was also decreased and the magnitude of the reduction was correlated with the decrease in ΔLCBF/ΔMVO₂ (r=0.82). These results suggest that adenosine may play an role in coronary functional hyperemia induced by increases in heart rate.

The hematological and rheological characteristics of blood from a number of vertebrates was compared to assess possible species differences in blood viscosity that may influence cardiovascular oxygen transport. Nucleated red blood cells (RBCs) were more viscous (measured by cone-plate viscometry) in comparison with enucleate (mammalian) RBCs at hematocrits greater than 40% when measured at equivalent temperatures. The lower viscosity of enucleate RBCs is attributed to an enhanced deformability of enucleate cells in comparison to nucleated cells.

Doctor of Philosophy / In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.