O transplante cardíaco (TX) é um reconhecido procedimento de escolha para a insuficiência cardíaca refratária, resultando em melhora na sintomatologia e na qualidade de vida dos pacientes. Todavia, estes pacientes apresentam capacidade física reduzida e alta prevalência de comorbidades. A terapia imunossupressora, bem como a denervação cardíaca pós-cirurgia tornam a hipertensão arterial sistêmica (HAS) a mais prevalente das comorbidades. Avaliamos o efeito agudo do exercício aeróbio em piscina aquecida e em solo sobre a dinâmica do comportamento tensional na pressão arterial durante 24 horas (MAPA-24h) e na atividade autonômica do coração. Dezoito pacientes (6 mulheres) clinicamente estáveis (5 ± 0,7 anos de cirurgia), 45,7 ± 2,7 anos de idade, foram submetidos a 30 minutos de exercício aeróbio em piscina, exercício aeróbio em esteira rolante (solo) ou 30 minutos em repouso (controle) em ordem randômica (2 a 5 dias entre cada sessão). A intensidade do exercício foi entre 11 e 13 em uma escala subjetiva de esforço que vai de 6 a 20. Foram avaliadas a variabilidade da frequência cardíaca (VFC) no início, logo após o exercício e na fase de recuperação, bem como a MAPA-24h após cada sessão. Após o exercício em piscina, foram observadas reduções significativas em relação à sessão controle nas médias horárias da pressão arterial sistólica (PAS) nas três primeiras horas (15h = 12,2 ± 3,1 mmHg, p = 0,004; 16h = 11,1 ± 2,8 mmHg, p = 0,003; 17h = 12,3 ± 3,1 mmHg, p =0,003) e após a sétima hora (21h = 7,8 ± 1,7 mmHg, p = 0,001) de análise, e nas médias diária (4 ± 1,6 mmHg, p = 0,02) e horária da pressão arterial diastólica (PAD) na primeira (15h = 7,7 ± 2,8 mmHg, p = 0,04) e sétima hora (21h = 6,6 ± 1,5 mmHg, p = 0,002). Após o exercício em solo foram vistas reduções significativas em relação à sessão controle nas médias horárias da PAS durante a segunda (16h = 5,3 ± 1,6 mmHg, p = 0,01), terceira (17h = 7,3 ± 2,3 mmHg, p = 0,02) e vigésima primeira hora (11h = 7,8 ± 1,7 mmHg, p = 0,02) e nas médias horárias da PAD durante a segunda (16h = 5,0 ± 1,7 mmHg, p = 0,04), a vigésima primeira (11h = 8,3 ± 2,5 mmHg, p = 0,01) e vigésima quarta hora (14h = 6,9 ± 2,4 mmHg, p = 0,03) de análise. A VFC apresentou não diferença significativa em nenhuma das intervenções de exercício. Assim sendo, ambas as sessões de exercício promoveram reduções similares da pressão arterial ambulatorial dos pacientes pós-TX, sugerindo que elas podem ser uma importante ferramenta para o combate da HAS nessa população de alto risco / Heart transplantation (TX) is a recognized procedure of choice for refractory heart failure, resulting in improvement in symptoms and quality of life of patients. However, these patients have reduced physical capacity and high prevalence of comorbidities. Immunosuppressive therapy and post-surgery cardiac denervation make systemic hypertension (SH) the most prevalent comorbiditie. We evaluated the acute effect of aerobic heated water-based exercise and land-based exercise on the dynamic tension behavior in blood pressure for 24 hours (24-h ABP) and autonomic activity of the heart. Eighteen patients (6 females) clinically stable (5 ± 0.7 years of surgery), 45.7 ± 2.7 years old, underwent 30 minutes of aerobic exercise in the swimming pool, aerobic exercise on a treadmill (land) or non-exercise control (control) in random order (2-5 days between each session). Exercise intensity was set at 11-13 in the 6-20 rating of perceived exertion scale. We evaluated the heart rate variability (HRV) at the beginning, right after exercise and during the recovery phase, and the 24-h ABP after each session. After water-based exercise, significant reductions were observed in relation to the control session on hourly average systolic blood pressure (SBP) in the first three hours (15h = 12.2 ± 3.1 mmHg, p = 0.004; 16h = 11.1 ± 2.8 mmHg, p = 0.003; 17h = 12.3 ± 3.1 mmHg, p = 0.003) and after the seventh time (21h = 7.8 ± 1.7 mmHg, p = 0.001) analysis, and the daily averages (4 ± 1.6 mmHg, p = 0.02) and hourly average diastolic blood pressure (DBP) in the first (15h = 7.7 ± 2.8 mmHg, p = 0.04) and seventh hours ( 21h = 6.6 ± 1.5 mmHg, p = 0.002). After land-based exercise significant reductions were observed when compared to control session in the hourly averages of SBP during the second (16h = 5.3 ± 1.6 mmHg, p = 0.01), third (17h = 7.3 ± 2 , 3 mm Hg, p = 0.02) and twenty-first time (= 11h 7.8 ± 1.7 mmHg, p = 0.02) and in hourly averages DBP during the second (= 16h 5.0 ± 1 7 mm Hg, p = 0.04), the twenty-first (11h = 8.3 ± 2.5 mmHg, p = 0.01) and twenty fourth hour (14h = 6.9 ± 2.4 mmHg, p = 0 03) analysis. HRV showed no significant difference in any of exercise interventions. Therefore, both exercise sessions promoted similar reductions in ambulatory blood pressure of post-TX patients, suggesting that they can be an important tool to counteract hypertension in this high-risk population

O exercício físico é componente fundamental na abordagem terapêutica não medicamentosa da hipertensão, mas pouco se conhece sobre a manipulação dos componentes da carga do treino aeróbio sobre a magnitude e duração da Hipotensão Pós-exercício (HPE) e redução crônica da Pressão Arterial (PA). Este estudo de abordagem quase-experimental teve o objetivo de avaliar as respostas hemodinâmicas de idosos hipertensos aos treinos intervalados de longa e de curta duração. A amostra foi composta por 33 idosos hipertensos que participam de atividades promovidas por um Programa de Integração Comunitária (PIC) de um município do interior paulista. As variáveis estudadas foram agrupadas nas categorias: sociodemográficas, antropométricas e hemodinâmicas. Após avaliação ergométrica, cada participante foi submetido a duas sessões de exercício físico, com intervalo de uma semana entre os treinos. Na sessão de treino intervalado de longa duração os participantes realizaram sete séries de quatro minutos a 90% da Frequência Cardíaca (FC) máxima por dois minutos de recuperação a 60% da FC máxima, com a duração total de 47 minutos. Na sessão de treino intervalado de curta os participantes realizaram três séries de quatro minutos a 90% da FC máxima por dois minutos de recuperação a 60% da FC máxima, no tempo total de 23 minutos. Para obtenção dos dados hemodinâmicos (FC, PA e Duplo Produto), os participantes realizaram três exames de Monitorização Ambulatorial da Pressão Arterial (MAPA), com duração de 24 horas: MAPA controle, MAPA após exercício intervalado de longa duração e MAPA após exercício intervalado de curta duração. Na sua maioria, a amostra foi composta por indivíduos do sexo feminino (63,6%), com 67,79 ± 4,72 anos de idade, de cor branca (75,6%), convivendo com companheiro (63,6%), com 9,42 ± 1,88 anos de estudo, aposentados (100%). A média de Índice de Massa Corporal (IMC) foi igual a 29,6 ± 2,24 Kg/m2 e de Circunferência Abdominal (CA) igual a 92,7 ± 6,01 cm. Os valores médios de Pressão Arterial Sistólica (PAS) (142 ± 10,86 mmHg) e Pressão Arterial Diastólica (PAD) (85 ± 8,99 mmHg) no período de 24 horas, obtidos pelo exame de MAPA controle (basal), mostraram-se superiores aos índices de normalidade preconizados pela 7ª Diretriz Brasileira de Hipertensão Arterial. Quando comparamos os resultados dos exames de MAPA após as sessões de treinos intervalados de curta e de longa duração com os valores resultantes da MAPA controle, encontramos diferença estatisticamente significante (p<0,001) para todos as variáveis clínicas investigadas, com redução dos parâmetros nos períodos de vigília, sono e 24 horas, após ambos os tipos de treinamento. Houve diferença (p=0,027) na magnitude de redução da PAS após treino intervalado de longa duração (114 ± 7,13 mmHg) em relação ao treino intervalado de curta duração (118 ± 5,22 mmHg), no período de 24 horas. Também observamos diferença (p=0,044) na redução da PAD após treino intervalado de longa duração (63 ± 6,22 mmHg) em comparação aos valores obtidos após treino intervalado de curta duração (65 ± 4,46 mmHg) no período de sono. Na primeira hora após as sessões de treinos intervalados de curta e longa duração houve expressiva HPE, constatada pela redução estatisticamente significante da PAS e da PAD (p<0,001) em relação aos valores préexercício, nas medidas obtidas em todos os intervalos (10, 20, 30, 40, 50 e 60 minutos). O decréscimo de PA na primeira hora após o exercício de curta duração foi igual a 27 mmHg e, após o treino de longa duração, igual a 29 mmHg. Os resultados apontaram diferença quando comparados os valores da PA resultantes dos treinos intervalados de alta intensidade e curta duração e de alta intensidade e longa duração, observadas na PAS (p<0,001) a partir dos 20 minutos após os treinamentos até os 60 minutos e na PAD, dos 40 aos 60 minutos (p<0,001). Os resultados de nosso estudo nos permitem concluir que, tanto o método de treino intervalado de longa duração como o intervalado de curta duração promovem diminuição da PAS, da PAD e redução da sobrecarga cardíaca em idosos hipertensos, ao longo das 24 horas subsequentes às sessões de treino, comparado ao dia em que não houve a prática de exercício físico. Salientamos que o treino de curta duração possibilita o incremento da adesão individual aos programas de exercícios. A persistência dos benefícios fisiológicos ao longo das 24 horas minimiza a necessidade de treino diário e fornece condições de maior aderência à prática. Em hipertensos, essa modalidade de treinamento impacta no controle da PA com consequente redução do risco cardiovascular, sendo uma alternativa valiosa no tratamento não medicamentoso da HA ou de outras doenças cardiovasculares / Physical exercise is a fundamental component in nonpharmacological approaches of hypertension, however little is known about the manipulation of aerobic training load components on post-exercise hypotension (PEH) magnitude, duration and in the chronic reduction of arterial pressure (AP). In this study we performed experiments to evaluate the hemodynamic responses on hypertensive elderly patients after long and short-interval training. The sample consisted of 33 hypertensive elderly who participated in activities provided by a philanthropic entity in a country side town of Sao Paulo state. In the studied variables the following categories were considered: sociodemographic, anthropometric and hemodynamic. After ergometric test, each subject underwent two sessions of dynamic exercises at a minimum one week interval between sessions. During the long interval training session - 47 minutes total exercise volume - each participant performed seven bouts of 4 minutes at 90% maximal heart rate (MHR) separated by 2 minutes recovery phase at 60% maximal heart rate (MHR). At the same time, during the short-interval training session - 23 minutes total exercise volume - each participant performed three bouts of 4 minutes at 90% maximal heart rate (MHR) separated by 2 minutes recovery phase at 60% maximal heart rate (MHR). For hemodynamic data (HR, AP and DP) the participants underwent three ambulatory blood pressure monitoring (ABPM) exams during 24 hours: ABPM control, ABPM after long interval training and ABPM after short-interval training. For the most part, the sample consisted of female participants (63,6%), aged 67,79 ± 4,72 years, white participants (75,6%), 63,6% of women had a partner, 100% were retired and the duration of the study was 9,42 ± 1,88 years. The mean body mass index (BMI) was 29,6 ± 2,24 Kg/m2 and the abdominal circumference (AC) was 92,7 ± 6,01 cm. The average level of the systolic blood pressure (SBP: 142 ± 10,86 mmHg) and the diastolic blood pressure (DBP: 85 ± 8,99 mmHg) recorded during 24 hours ABPM control were higher than the ideal blood pressure recommended by the VII Brazilian Guidelines on Ambulatory Blood Pressure Monitoring. When comparing ABPM exams results after long and short-intervals training sessions with the results of ABPM control, all clinical variables investigated differ significantly (p<0,001). Both training sessions revealed reduction of parameters during 24 hours, awaken and sleeping period. There was difference (p=0,027) in the reduction magnitude of SBP after long interval training (114 ± 7,13 mmHg) when compared to short-interval training data (118 ± 5,22 mmHg) within 24 hours. During the sleeping period we also observed that there was a difference (p=0,044) in the DBP after long interval training (63 ± 6,22 mmHg) when compared to short-interval training data (65 ± 4,46 mmHg). In the first hour after the long and short-interval training sessions there was a striking PEH that was verified by the statistically significant reduction of SBP and DBP (p<0,01) compared to data pre-exercise. This result was obtained in all intervals (10, 20, 30, 40, 50 and 60 minutes). The decrease in AP in the first hour after short-interval training corresponded to 27mmHg and after long interval training it was 29 mmHg. We noticed that there was difference between the values of AP when the long term high intensity interval training was compared to the short term high intensity interval training. For SBP (p<0,001) the difference was from 20 minutes up to 60 minutes and for DBP (p<0,001) the difference was from 40 minutes up to 60 minutes. In conclusion we show that short and long interval training leads to a reduction in SBP, DBP and decline in cardiovascular overload of hypertensive elderly in the 24 hours following exercise practice when compared to the day of no physical activity. We point out that the short-interval training encourages patients\' adherence to exercise programs. Since the physiological benefits of the short and long interval training lasts 24 hours it eliminates the need for their daily exercise routine. This training approach can be particularly useful for hypertensive individuals as it leads to AP control with subsequently reduction in cardiovascular risk becoming a valuable alternative in nonpharmacological treatment of AH and other cardiovascular diseases

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-08-08T14:40:53Z No. of bitstreams: 1 MariaEdilmadaSilvaBezerraDissertacao2018.pdf: 1352574 bytes, checksum: 329c4e9b5bb3df4f0c7059f59c9e1648 (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-08-08T14:41:04Z (GMT) No. of bitstreams: 1 MariaEdilmadaSilvaBezerraDissertacao2018.pdf: 1352574 bytes, checksum: 329c4e9b5bb3df4f0c7059f59c9e1648 (MD5) / Made available in DSpace on 2018-08-08T14:41:04Z (GMT). No. of bitstreams: 1 MariaEdilmadaSilvaBezerraDissertacao2018.pdf: 1352574 bytes, checksum: 329c4e9b5bb3df4f0c7059f59c9e1648 (MD5) Previous issue date: 2018-03-02 / Studies have shown that even a single session of physical exercise lowers blood pressure after its completion. This phenomenon is called post-exercise hypotension (PEH), and has been considered as a non-pharmacological way to control blood pressure. However, there are no studies regarding the occurrence of PEH after acute exercise in individuals with Down Syndrome (DS). This study aimed to analyze the occurrence of PEH in these individuals and the possible role of exercise intensity. Ten individuals with DS, of both genders, participated in the study (age, 29 ± 7 years, body mass, 60.7 ± 9 kg, height, 1.48 ± 0.11 cm and BMI, 27.6 ± 2.4 kg/m²). Volunteers randomly underwent two sessions of exercise on a stationary bike for 20 minutes and a sham control session. Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured after 15 minutes of resting, at the 20th minute of each exercise session or control, and at 15th, 30th and 45th minutes of post-exercise recovery. Both moderate and intense exercise performed acutely increased SBP (p<0.001; p<0.01, respectively) with no effect on DPB levels in individuals with DS. However, neither the moderate nor the intense exercise were enough to elicit PEH. The results indicated that individuals with DS may not present PEH for the intensities, duration and exercise mode as applied in the present investigation. While additional studies with different exercise strategies are needed, our findings contribute to the body of literature regarding the PEH responses in adults with DS. / Estudos demonstraram que mesmo em uma única sessão de exercício físico há a redução da pressão arterial após sua realização. Este fenômeno é chamado de hipotensão pós-exercício (HPE) e foi considerado como uma forma não farmacológica de controlar a pressão arterial. No entanto, não há estudos sobre a ocorrência de HPE após o exercício agudo em indivíduos com síndrome de Down (SD). Este estudo teve como objetivo analisar a ocorrência de HPE nesses indivíduos e o possível papel da intensidade do exercício. Participaram do estudo: dez indivíduos com SD, 7 do sexo masculino e 3 do feminino, (idade, 29 ± 7 anos, massa corporal, 60,7 ± 9 kg, altura, 1,48 ± 0,11 cm e IMC, 27,6 ± 2,4 kg / m²). Os voluntários passaram, aleatoriamente, por duas sessões de exercício em uma bicicleta estacionária, por 20 minutos, e uma sessão de controle simulada. A frequência cardíaca (FC), pressão arterial sistólica (PAS) e a pressão arterial diastólica (PAD) foram medidas após 15 minutos de repouso, no vigésimo minuto de cada sessão de exercício ou controle, e aos 15, 30 e 45 minutos do pós-exercício recuperação. Os exercícios moderados e intensos provocaram um aumento agudo da PAS (p <0,001; p <0,01, respectivamente) sem efeito nos níveis de PAD em indivíduos com SD. No entanto, nem o exercício moderado nem o exercício intenso foram suficientes para provocar HPE. Os resultados indicaram que indivíduos com SD não apresentaram HPE para as intensidades, duração e modo de exercícios aplicados na presente investigação. Embora sejam necessários estudos adicionais com diferentes estratégias de exercícios, nossos resultados contribuem para o corpo da literatura em relação às respostas de HPE em adultos com SD.

O transplante cardíaco (TX) é um reconhecido procedimento de escolha para a insuficiência cardíaca refratária, resultando em melhora na sintomatologia e na qualidade de vida dos pacientes. Todavia, estes pacientes apresentam capacidade física reduzida e alta prevalência de comorbidades. A terapia imunossupressora, bem como a denervação cardíaca pós-cirurgia tornam a hipertensão arterial sistêmica (HAS) a mais prevalente das comorbidades. Avaliamos o efeito agudo do exercício aeróbio em piscina aquecida e em solo sobre a dinâmica do comportamento tensional na pressão arterial durante 24 horas (MAPA-24h) e na atividade autonômica do coração. Dezoito pacientes (6 mulheres) clinicamente estáveis (5 ± 0,7 anos de cirurgia), 45,7 ± 2,7 anos de idade, foram submetidos a 30 minutos de exercício aeróbio em piscina, exercício aeróbio em esteira rolante (solo) ou 30 minutos em repouso (controle) em ordem randômica (2 a 5 dias entre cada sessão). A intensidade do exercício foi entre 11 e 13 em uma escala subjetiva de esforço que vai de 6 a 20. Foram avaliadas a variabilidade da frequência cardíaca (VFC) no início, logo após o exercício e na fase de recuperação, bem como a MAPA-24h após cada sessão. Após o exercício em piscina, foram observadas reduções significativas em relação à sessão controle nas médias horárias da pressão arterial sistólica (PAS) nas três primeiras horas (15h = 12,2 ± 3,1 mmHg, p = 0,004; 16h = 11,1 ± 2,8 mmHg, p = 0,003; 17h = 12,3 ± 3,1 mmHg, p =0,003) e após a sétima hora (21h = 7,8 ± 1,7 mmHg, p = 0,001) de análise, e nas médias diária (4 ± 1,6 mmHg, p = 0,02) e horária da pressão arterial diastólica (PAD) na primeira (15h = 7,7 ± 2,8 mmHg, p = 0,04) e sétima hora (21h = 6,6±1,5 mmHg, p = 0,002). Após o exercício em solo foram vistas reduções significativas em relação à sessão controle nas médias horárias da PAS durante a segunda (16h = 5,3±1,6 mmHg, p = 0,01), terceira (17h = 7,3 ± 2,3 mmHg, p = 0,02) e vigésima primeira hora (11h = 7,8 ± 1,7 mmHg, p = 0,02) e nas médias horárias da PAD durante a segunda (16h = 5,0 ± 1,7 mmHg, p = 0,04), a vigésima primeira (11h = 8,3 ± 2,5 mmHg, p = 0,01) e vigésima quarta hora (14h = 6,9 ± 2,4 mmHg, p = 0,03) de análise. A VFC apresentou não diferença significativa em nenhuma das intervenções de exercício. Assim sendo, ambas as sessões de exercício promoveram reduções similares da pressão arterial ambulatorial dos pacientes pós-TX, sugerindo que elas podem ser uma importante ferramenta para o combate da HAS nessa população de alto risco / Heart transplantation (TX) is a recognized procedure of choice for refractory heart failure, resulting in improvement in symptoms and quality of life of patients. However, these patients have reduced physical capacity and high prevalence of comorbidities. Immunosuppressive therapy and post-surgery cardiac denervation make systemic hypertension (SH) the most prevalent comorbiditie. We evaluated the acute effect of aerobic heated water-based exercise and land-based exercise on the dynamic tension behavior in blood pressure for 24 hours (24-h ABP) and autonomic activity of the heart. Eighteen patients (6 females) clinically stable (5 ± 0.7 years of surgery), 45.7 ± 2.7 years old, underwent 30 minutes of aerobic exercise in the swimming pool, aerobic exercise on a treadmill (land) or non-exercise control (control) in random order (2-5 days between each session). Exercise intensity was set at 11-13 in the 6-20 rating of perceived exertion scale. We evaluated the heart rate variability (HRV) at the beginning, right after exercise and during the recovery phase, and the 24-h ABP after each session. After water-based exercise, significant reductions were observed in relation to the control session on hourly average systolic blood pressure (SBP) in the first three hours (15h = 12.2 ± 3.1 mmHg, p = 0.004; 16h = 11.1 ± 2.8 mmHg, p = 0.003; 17h = 12.3 ± 3.1 mmHg, p = 0.003) and after the seventh time (21h = 7.8 ± 1.7 mmHg, p = 0.001) analysis, and the daily averages (4 ± 1.6 mmHg, p = 0.02) and hourly average diastolic blood pressure (DBP) in the first (15h = 7.7 ± 2.8 mmHg, p = 0.04) and seventh hours ( 21h = 6.6 ± 1.5 mmHg, p = 0.002). After land-based exercise significant reductions were observed when compared to control session in the hourly averages of SBP during the second (16h = 5.3 ± 1.6 mmHg, p = 0.01), third (17h = 7.3 ± 2 , 3 mm Hg, p = 0.02) and twenty-first time (= 11h 7.8 ± 1.7 mmHg, p = 0.02) and in hourly averages DBP during the second (= 16h 5.0 ± 1 7 mm Hg, p = 0.04), the twenty-first (11h = 8.3 ± 2.5 mmHg, p = 0.01) and twenty fourth hour (14h = 6.9 ± 2.4 mmHg, p = 0 03) analysis. HRV showed no significant difference in any of exercise interventions. Therefore, both exercise sessions promoted similar reductions in ambulatory blood pressure of post-TX patients, suggesting that they can be an important tool to counteract hypertension in this high-risk population

O treinamento resistido (TR) de alta intensidade tem sido recomendado para reverter as alterações musculares promovidas pelo envelhecimento. Porém, o envelhecimento também se associa de aumento da pressão arterial (PA). Uma sessão de TR promove hipotensão pós-exercício em jovens, mas este efeito não está claro em idosos, sendo este o objetivo dessa dissertação. 16 idosos participaram, após 10-12 semanas de TR, de 2 sessões realizadas em ordem aleatória: Controle-C (repouso) e Exercício-E (3 séries, 8 RM, 7 exercícios). A PA, o débito cardíaco (DC), a freqüência cardíaca (FC), a modulação autonômica cardiovascular foram medidos pré e 60 min pós-intervenções e a PA ambulatorial foi medida por 24 h. A PA sistólica e média aumentaram na sessão C e não se modificaram na E, resultando num efeito hipotensor de -6,4±1,9 e -2,9±0,2 mmHg. A PA diastólica e a resistência vascular periférica (RVP) aumentaram de forma similar nas 2 sessões (+2,0±0,7 mmHg e +3,8±0,7 mmHg.min/l), enquanto que o DC e o volume sistólico (VS) diminuíram, e a FC, o duplo produto (DP) e a razão entre as bandas de baixa e alta freqüência da variabilidade do intervalo R-R aumentaram na sessão E (-0,5±0,1 l/min, -9,3±2,0 ml, +3,8±1,6 bpm, +579,3±164,1 mmHg/bpm e +0,71±0,35). Não houve diferença na PA de 24h, mas a FC e o DP permaneceram aumentados por 5,5 h pós-exercício. Assim, uma sessão de TR de alta intensidade teve efeito hipotensor em idosos treinados, que foi mediado pela redução do DC, promovida pela diminuição do VS, que não foi compensada apesar do aumento da FC, induzida pelo aumento da modulação simpática para o coração. O efeito hipotensor não perdurou pelas demais horas, mas o trabalho cardíaco ficou aumentado por até 5,5 h pós-exercício / High-intensity resistance training (RT) is recommended to delay the effects of aging on skeletal muscle. However, aging is also accompanied by blood pressure (BP) increases. Its known that each RT session promotes post-exercise hypotension in young, but this effect wasnt clear in elderly. Thus, this was the aim of the present study. 16 elderly subjects, who were already participating in a RT program, underwent, in a random order, 2 sessions: Control (C) remained seated and Exercise (E) 7 resistance exercises, 3 sets, 8 RM. BP, cardiac output (CO), heart rate (HR) and cardiovascular autonomic regulation were measured before and 60 min after interventions, while ambulatory BP was measured for 24 h. Systolic and mean BP increased in the C, but did not change in the E, resulting in a hypotensive effects of -6.4±1.9 and -2.9±0.2 mmHg, respectively. Diastolic BP and systemic vascular resistance (SVR) increased similarly in both sessions (+2.0±0.7 mmHg and +3.8±0.7 mmHg.min/l), while CO and stroke volume (SV) decreased, and HR, rate-pressure product (RPP) and low to high-frequency ratio of the R-R interval variability only increased in the E (-0.5±0.1l/min, -9.3±2.0ml/beat, +3.8±1.6beat/min, +579.3±164.1 mmHg/beat/min and +0.71±0.35). Ambulatory BP was similar in both sessions, but HR and RPP were increased for 5,5 h after exercise. In conclusion, a session of high-intensity RT promoted post-exercise hypotensive effects in trained elderly. This effect was mediated by a decrease in CO, produced by a reduction in SV that was not compensated besides the increase in HR, promoted by an increase in sympathetic modulation to the heart. The hypotensive effect was not sustained during daily activities, and cardiac work was kept sustained elevated for 5,5 h post-exercise

Os jogos de realidade virtual (JRV) são utilizados como estratégia complementar de reabilitação motora em indivíduos pós-acidente vascular cerebral (AVC). Porém, o impacto cardiovascular e metabólico desses jogos foi pouco investigado, o que é essencial para uma reabilitação completa. Com esse intuito, este estudo avaliou as respostas de frequência cardíaca (FC) e consumo de oxigênio (VO2) durante os JRV, comparando-as ao limiar anaeróbio (Lan) e ao ponto de compensação respiratória (PCR) e calculando o gasto energético (GE). Além disso, investigou-se as respostas da FC, pressão arterial (PA) e duplo produto (DP) no período pós-JRV e a reprodutibilidade de todas as respostas aos JRV. Para tanto, 12 indivíduos (84% homens, 56±12 anos) em fase crônica após um único AVC participaram, em ordem aleatória, de três sessões experimentais, sendo duas delas de JRV e uma controle. Nas sessões de JRV, os indivíduos foram submetidos a 4 blocos de jogos intercalados por 2 min de pausa; cada bloco foi composto por 3 min do jogo Tênis de Mesa, seguidos de 1 min de pausa e 4 min do jogo Boxe (Xbox360+Kinect). Na sessão controle, os indivíduos assistiram a um filme sentados por 38 min. A FC e o VO2 foram continuamente medidos durante as sessões, e a PA e FC foram medidas antes e aos 15 e 30 min após as intervenções. O GE foi calculado a partir do VO2. As respostas de FC e VO2 nos JRV tiveram boa reprodutibilidade (coeficiente de correlação intraclasse > 0,75 e baixo erro médio da medida). Os valores de FC medidos durante os JRV foram semelhantes ao Lan e significantemente inferiores ao PCR, com mais de 50% dos indivíduos apresentando FC abaixo do Lan em todos os JRV. O VO2 medido durante os JRV foi significantemente menor que o Lan e o PCR, com mais de 75% dos indivíduos com VO2 abaixo do Lan em todos os jogos. O GE médio da sessão de JRV foi de ? 4,6±0,1 kcal/min, totalizando 169±11 kcal. Após a sessão de JRV, a PA não se modificou, a FC e o DP permaneceram aumentados por 30 min. Conclui-se que, em indivíduos pós-AVC, a sessão de JRV proposta promoveu respostas fisiológicas reprodutíveis, que corresponderam a uma intensidade próxima e abaixo do Lan, gerando um GE médio de cerca de 4 kcal/min (3 METS) e mantendo o trabalho cardíaco aumentado por até 30 min após a sessão / Virtual reality games (VRG) has been used as a complementary strategy for motor rehabilitation in stroke survivors. However, the cardiovascular and metabolic impacts produced by these games has been poorly investigated, which is important for a complete rehabilitation. To investigate this impact, this study evaluated heart rate (HR) and oxygen consumption (VO2) responses during VRG, comparing these responses with anaerobic threshold (AT) and respiratory compensation point (RCP), and calculating the energy expenditure (EE). Furthermore, the responses of HR, blood pressure (BP) and rate pressure product (RPP) after the VRG session as well as the reproducibility of all the responses to VRG were evaluated. For that, 12 chronic post-stroke patients (84% men, 56±12 years) underwent, in random order, 3 experimental sessions: two composed by VRG and one control session. The VRG sessions were composed by 4 blocks of games interpolated by 2 min of rest, and each block was composed by 3 min of the table tennis game followed by 1 min of rest and 4 min of the boxing game (Xbox360+Kinect). In the control session, the subjects watched a film in the seating position for 38 min. HR and VO2 were continuously measured during the sessions, and HR and BP were also measured before and at 15 and 30 min after the interventions. EE was calculated from VO2. HR and VO2 responses to VRG showed good reproducibility (intraclass correlation index > 75% and low standard error of measurement). HR measured during the VRG was similar to AT and significantly lower than RCP, with more than 50% of the subjects presenting HR below AT in all the games. VO2 measured during the VRG was significantly lower than AT and RCP, with more than 75% of the subjects presenting VO2 below AT in all the games. VRG EE was ?4.6±0.1 kcal/min, totalizing 169±11 kcal. After the VRG session, BP did not change, while HR and RPP remained significantly increased up to 30 min. In conclusion, in post-stroke survivors, the proposed VRG session produced physiological responses that have good reproducibility and corresponded to an intensity near to and below the AT, generating a mean EE of 4 kcal/min (3 METs), and maintaining cardiac work elevated for at least 30 min after its end

O exercício físico é componente fundamental na abordagem terapêutica não medicamentosa da hipertensão, mas pouco se conhece sobre a manipulação dos componentes da carga do treino aeróbio sobre a magnitude e duração da Hipotensão Pós-exercício (HPE) e redução crônica da Pressão Arterial (PA). Este estudo de abordagem quase-experimental teve o objetivo de avaliar as respostas hemodinâmicas de idosos hipertensos aos treinos intervalados de longa e de curta duração. A amostra foi composta por 33 idosos hipertensos que participam de atividades promovidas por um Programa de Integração Comunitária (PIC) de um município do interior paulista. As variáveis estudadas foram agrupadas nas categorias: sociodemográficas, antropométricas e hemodinâmicas. Após avaliação ergométrica, cada participante foi submetido a duas sessões de exercício físico, com intervalo de uma semana entre os treinos. Na sessão de treino intervalado de longa duração os participantes realizaram sete séries de quatro minutos a 90% da Frequência Cardíaca (FC) máxima por dois minutos de recuperação a 60% da FC máxima, com a duração total de 47 minutos. Na sessão de treino intervalado de curta os participantes realizaram três séries de quatro minutos a 90% da FC máxima por dois minutos de recuperação a 60% da FC máxima, no tempo total de 23 minutos. Para obtenção dos dados hemodinâmicos (FC, PA e Duplo Produto), os participantes realizaram três exames de Monitorização Ambulatorial da Pressão Arterial (MAPA), com duração de 24 horas: MAPA controle, MAPA após exercício intervalado de longa duração e MAPA após exercício intervalado de curta duração. Na sua maioria, a amostra foi composta por indivíduos do sexo feminino (63,6%), com 67,79 ± 4,72 anos de idade, de cor branca (75,6%), convivendo com companheiro (63,6%), com 9,42 ± 1,88 anos de estudo, aposentados (100%). A média de Índice de Massa Corporal (IMC) foi igual a 29,6 ± 2,24 Kg/m2 e de Circunferência Abdominal (CA) igual a 92,7 ± 6,01 cm. Os valores médios de Pressão Arterial Sistólica (PAS) (142 ± 10,86 mmHg) e Pressão Arterial Diastólica (PAD) (85 ± 8,99 mmHg) no período de 24 horas, obtidos pelo exame de MAPA controle (basal), mostraram-se superiores aos índices de normalidade preconizados pela 7ª Diretriz Brasileira de Hipertensão Arterial. Quando comparamos os resultados dos exames de MAPA após as sessões de treinos intervalados de curta e de longa duração com os valores resultantes da MAPA controle, encontramos diferença estatisticamente significante (p<0,001) para todos as variáveis clínicas investigadas, com redução dos parâmetros nos períodos de vigília, sono e 24 horas, após ambos os tipos de treinamento. Houve diferença (p=0,027) na magnitude de redução da PAS após treino intervalado de longa duração (114 ± 7,13 mmHg) em relação ao treino intervalado de curta duração (118 ± 5,22 mmHg), no período de 24 horas. Também observamos diferença (p=0,044) na redução da PAD após treino intervalado de longa duração (63 ± 6,22 mmHg) em comparação aos valores obtidos após treino intervalado de curta duração (65 ± 4,46 mmHg) no período de sono. Na primeira hora após as sessões de treinos intervalados de curta e longa duração houve expressiva HPE, constatada pela redução estatisticamente significante da PAS e da PAD (p<0,001) em relação aos valores préexercício, nas medidas obtidas em todos os intervalos (10, 20, 30, 40, 50 e 60 minutos). O decréscimo de PA na primeira hora após o exercício de curta duração foi igual a 27 mmHg e, após o treino de longa duração, igual a 29 mmHg. Os resultados apontaram diferença quando comparados os valores da PA resultantes dos treinos intervalados de alta intensidade e curta duração e de alta intensidade e longa duração, observadas na PAS (p<0,001) a partir dos 20 minutos após os treinamentos até os 60 minutos e na PAD, dos 40 aos 60 minutos (p<0,001). Os resultados de nosso estudo nos permitem concluir que, tanto o método de treino intervalado de longa duração como o intervalado de curta duração promovem diminuição da PAS, da PAD e redução da sobrecarga cardíaca em idosos hipertensos, ao longo das 24 horas subsequentes às sessões de treino, comparado ao dia em que não houve a prática de exercício físico. Salientamos que o treino de curta duração possibilita o incremento da adesão individual aos programas de exercícios. A persistência dos benefícios fisiológicos ao longo das 24 horas minimiza a necessidade de treino diário e fornece condições de maior aderência à prática. Em hipertensos, essa modalidade de treinamento impacta no controle da PA com consequente redução do risco cardiovascular, sendo uma alternativa valiosa no tratamento não medicamentoso da HA ou de outras doenças cardiovasculares / Physical exercise is a fundamental component in nonpharmacological approaches of hypertension, however little is known about the manipulation of aerobic training load components on post-exercise hypotension (PEH) magnitude, duration and in the chronic reduction of arterial pressure (AP). In this study we performed experiments to evaluate the hemodynamic responses on hypertensive elderly patients after long and short-interval training. The sample consisted of 33 hypertensive elderly who participated in activities provided by a philanthropic entity in a country side town of Sao Paulo state. In the studied variables the following categories were considered: sociodemographic, anthropometric and hemodynamic. After ergometric test, each subject underwent two sessions of dynamic exercises at a minimum one week interval between sessions. During the long interval training session - 47 minutes total exercise volume - each participant performed seven bouts of 4 minutes at 90% maximal heart rate (MHR) separated by 2 minutes recovery phase at 60% maximal heart rate (MHR). At the same time, during the short-interval training session - 23 minutes total exercise volume - each participant performed three bouts of 4 minutes at 90% maximal heart rate (MHR) separated by 2 minutes recovery phase at 60% maximal heart rate (MHR). For hemodynamic data (HR, AP and DP) the participants underwent three ambulatory blood pressure monitoring (ABPM) exams during 24 hours: ABPM control, ABPM after long interval training and ABPM after short-interval training. For the most part, the sample consisted of female participants (63,6%), aged 67,79 ± 4,72 years, white participants (75,6%), 63,6% of women had a partner, 100% were retired and the duration of the study was 9,42 ± 1,88 years. The mean body mass index (BMI) was 29,6 ± 2,24 Kg/m2 and the abdominal circumference (AC) was 92,7 ± 6,01 cm. The average level of the systolic blood pressure (SBP: 142 ± 10,86 mmHg) and the diastolic blood pressure (DBP: 85 ± 8,99 mmHg) recorded during 24 hours ABPM control were higher than the ideal blood pressure recommended by the VII Brazilian Guidelines on Ambulatory Blood Pressure Monitoring. When comparing ABPM exams results after long and short-intervals training sessions with the results of ABPM control, all clinical variables investigated differ significantly (p<0,001). Both training sessions revealed reduction of parameters during 24 hours, awaken and sleeping period. There was difference (p=0,027) in the reduction magnitude of SBP after long interval training (114 ± 7,13 mmHg) when compared to short-interval training data (118 ± 5,22 mmHg) within 24 hours. During the sleeping period we also observed that there was a difference (p=0,044) in the DBP after long interval training (63 ± 6,22 mmHg) when compared to short-interval training data (65 ± 4,46 mmHg). In the first hour after the long and short-interval training sessions there was a striking PEH that was verified by the statistically significant reduction of SBP and DBP (p<0,01) compared to data pre-exercise. This result was obtained in all intervals (10, 20, 30, 40, 50 and 60 minutes). The decrease in AP in the first hour after short-interval training corresponded to 27mmHg and after long interval training it was 29 mmHg. We noticed that there was difference between the values of AP when the long term high intensity interval training was compared to the short term high intensity interval training. For SBP (p<0,001) the difference was from 20 minutes up to 60 minutes and for DBP (p<0,001) the difference was from 40 minutes up to 60 minutes. In conclusion we show that short and long interval training leads to a reduction in SBP, DBP and decline in cardiovascular overload of hypertensive elderly in the 24 hours following exercise practice when compared to the day of no physical activity. We point out that the short-interval training encourages patients\' adherence to exercise programs. Since the physiological benefits of the short and long interval training lasts 24 hours it eliminates the need for their daily exercise routine. This training approach can be particularly useful for hypertensive individuals as it leads to AP control with subsequently reduction in cardiovascular risk becoming a valuable alternative in nonpharmacological treatment of AH and other cardiovascular diseases

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

This thesis examined the translocation of fatty acid (FA) transport proteins to the plasma membrane (PM) in human and rat skeletal muscle during moderate intensity exercise. The responses to the post-exercise period and to acute moderate intensity exercise after 6 weeks of high intensity interval training (HIIT) were also examined in humans. The overall hypotheses were that 1) FAT/CD36 and FABPpm would translocate to the PM in human skeletal muscle during 120 min of moderate intensity exercise, 2) FAT/CD36 and FABPpm would translocate to the PM in rat skeletal muscle during 120 min of moderate intensity exercise and this would correlate to an increase in palmitate uptake, 3) FAT/CD36 and FABPpm would translocate to the PM during 120 min of moderate intensity exercise, but return to basal levels by 45 min post-exercise, 4) six weeks of HIIT would increase PM content of FABPpm but not FAT/CD36 in resting skeletal muscle, 5) six weeks of HIIT would cause a further increase in the translocation of FAT/CD36 and FABPpm to the PM during moderate intensity exercise and this would correspond to an increase in whole body fat oxidation compared to exercise pre-training, and 6) six weeks of HIIT would increase whole muscle content of FATP1 and FATP4. In human skeletal muscle, PM FAT/CD36 and FABPpm increased 75% and 20% respectively after 120 min of cycling at ~60% VO2 peak which corresponded to a 110% increase in whole body fat oxidation. In rat skeletal muscle, PM FAT/CD36 and FABPpm increased 20% and 30% respectively, which correlated to a 30% increase in palmitate uptake following 120 min of treadmill running at ~65% VO2 peak. The PM content of FAT/CD36 increased further to 120% of resting values by 45 min of post-exercise following 120 min of cycling at ~60% VO2peak, which correlated with a heavy reliance on fat as a fuel during the post-exercise period. FABPpm returned to resting levels of PM content by 15 min post-exercise. After 6 wk of HIIT, whole muscle FAT/CD36 (50%), FABPpm (21%) and FATP4 (25%) were increased in human skeletal muscle, while FATP1 remained unchanged. There were no changes in PM content of FAT/CD36 or FABPpm at rest following training. FAT/CD36 and FABPpm were also measured before and after 120 min of cycling at ~60% of pre-trainingVO2 peak following training, but no differences in the magnitude of the PM content increases were seen compared to pre-training, despite a 27% increase in fat oxidation. These studies demonstrate that FA transport proteins translocate to the PM during moderate intensity exercise, which correlates with increased FA uptake and whole body fat oxidation. This relationship does not appear to hold during the post-exercise period, as further increases in the PM content of FAT/CD36 does not correspond with the decrease in fat oxidation. The PM content of FAT/CD36 and FABPpm were not increased at rest following training, and there was no effect of training on the translocation of FAT/CD36 or FABPpm to the PM during moderate intensity exercise at the same absolute power output, however there may be a further increase at a relative power output. / Natural Sciences and Engineering Research Council, Canadian Institute of Health Research, Ontario Graduate Scholarship

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.