Thesis (MScSportSc)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: There is a growing concern in South Africa and worldwide about the global epidemic of obesity and overweightness among the general population. Obesity mediates the pathogenesis of pathological conditions and is associated with a poor quality of life, high morbidity and mortality rates and a huge burden on an individual’s and the health system’s infrastructure and finances. The answer to this rising epidemic is weight loss. Endurance training has been shown to induce weight loss however, people usually cite lack of time as a barrier to meaningful participation in exercise programmes. High intensity interval training (HIIT) therefore emerges as a potential solution to these barriers as it takes a relatively short period of time compared to endurance training. Despite the differences in exercise durations the most cogent advantage is that HIIT elicits not just similar, but even superior central and peripheral adaptations. The central and peripheral adaptations have been shown to enhance weight loss, improve blood lipids and glucose levels, as well as decreasing blood pressure. The challenge facing exercise physiologists is to find the optimal exercise intensity and duration of HIIT bouts which would be time efficient, safe and well tolerated by overweight and obese people. The shortcomings of literature are that most HIIT studies have focused on healthy, overweight and obese men and these studies cannot be extrapolated to women who have been shown to respond differently to training. Moreover, other interventions investigating the effects of HIIT in women and men have been longer term rather than short term interventions. In order to fill the gaps in the literature, the main aim of this study was to investigate the training and detraining effects of a short-term HIIT programme on selected health-related measures in young overweight and obese women. To this end, a non-random sample of 20 overweight and obese women (aged 18-25) volunteered to participate in this study. Selected health-related outcomes were measured prior to training. The pre-training testing was followed by the HIIT intervention which was two weeks and consisted of six sessions using the 10 – 15x1 minute running at 90% HRmax which was separated by one minute active recovery periods at 50-60% of HRmax. The HIIT intervention was followed by a post test in which baseline measurements were repeated. This was then followed by a two week detraining period and follow up testing. The main finding of this study was that a period of two weeks of HIIT can elicit adaptations that can lower the risk profiles of young overweight and obese women. The results showed a statistically significant decrease in body mass (1.6%, p = 0.001), fat mass (3.7%, p = 0.001) and waist circumference (4.8%, p = 0.001), and an increase in lean mass of 1.9% (p = 0.001). There was also a decrease in blood glucose (11%, p = 0.001), total cholesterol (10.4 %, p = 0.01), systolic (3.4%, p = 0.001) and diastolic blood pressure (5.8%, p = 0.001) levels. Finally there was a statistically significant increase in relative VO2max and exercise capacity after the HIIT The follow-up testing after two weeks of detraining shows that the metabolic adaptations that were achieved by the HIIT protocol are relatively lasting or are at least not completely reversed. The weight loss induced by HIIT is important in that it is the major target in lowering the prevalence of overweightness and obesity. The HIIT protocol in this study emerges as a time efficient strategy in eliciting positive adaptations in clinical populations and healthy people. Moreover these findings suggest that 10 minute and 15 minute HIIT work bouts at near-maximal intensities are possibly the minimum amount of training that is needed to induce significant weight loss and other positive health-related outcomes. / AFRIKAANSE OPSOMMING: Daar bestaan ʼn toenemende besorgdheid in Suid-Afrika en wêreldwyd oor die globale epidemie van obesiteit en oorgewig onder die algemene bevolking. Obesiteit fasiliteer die patogenese van verskeie siektetoestande en word met ʼn swak kwaliteit lewe, hoë morbiditeit en mortaliteit en ʼn geweldige las op ʼn individu en die gesondheidsowerhede se infrastruktuur en finansies geassosieer. Een van die antwoorde op hierdie stygende epidemie is gewigsverlies. Dit is reeds gewys dat uithouvermoë oefening saam met ʼn kalorie beperkende dieet gewigsverlies in die hand werk. Mense dui egter ʼn tekort aan tyd as ʼn hindernis tot betekenisvolle deelname aan ʼn oefenprogram aan. Hoë intensiteit interval inoefening (HIIO) is dus ʼn potensiële oplossing tot hierdie hindernis aangesien dit in vergelyking met uithouvermoë inoefening in ʼn relatiewe korter periode van tyd uitgevoer kan word. Afgesien van die verskille in inoefenperiodes is die mees logiese voordeel dat die HIIO nie net soortgelyke nie, maar self beter sentrale en periferale fisiologiese aanpassing voortbring. Die sentrale en periferale aanpassing verhoog gewigsverlies, verbeter bloedlipiedes en glukose vlakke, en veroorsaak ʼn afname in bloeddruk. Alhoewel ʼn aantal studies die voordele van HIIO by jonger en ouer populasies aandui, is baie min studies op vrouens uitgevoer. Bevindinge kan nie noodwendig na vrouens ekstrapoleer word nie omdat hulle dikwels verskillend op inoefening as mans reageer. Dit is ook nie bekend of ʼn kort HIIO intervensie ʼn betekenisvolle impak op oorgewig en vetsugtige vrouens sou hê nie, asook hoe blywend enige veranderinge sou wees nie. Die hoofdoel van hierdie studie was dus om die inoefening- en die geen-inoefening effekte van ʼn korttermyn HIIO program op geselekteerde gesondheidskenmerke in jong oorgewig en vetsugtige dames te bepaal. ʼn Nie-ewekansige steekproef van 20 oorgewig en vetsugtige vrouens (18-25 jaar) het vrywillig ingestem om aan hierdie studie deel te neem. Geselekteerde gesondheidskenmerke is voor die aanvang van die inoefening gemeet. Die HIIO intervensie het twee weke geduur en het uit ses sessies bestaan (10 – 15x1 minuut draf by 90% HSmaks en een minuut aktiewe herstel by 50-60% HSmaks). Die HIIO intervensie is deur ʼn na-toets gevolg waarin basislyn metings herhaal is. Dit is deur ʼn twee weke geen-inoefening periode en opvolgtoetse opgevolg. Die hoofbevinding van hierdie studie was dat ses sessies van HIIO fisiologiese aanpassings na vore gebring het wat die risiko profiele van jong oorgewig en vetsugtige vrouens verlaag het. Daar was statisties betekenisvolle afnames in liggaamsmassa (1.6%, p < 0.001), vetmassa (3.7%, p < 0.001) en heupomtrek (4.8%, p < 0.001) en ʼn toename in vetvrye liggaamsmassa van 1.9% (p < 0.001). Daar was ook ʼn afname in bloedglukose (11%, p < 0.001), totale cholesterol (10.4 %, p = 0.01), sistoliese (3.4%, p < 0.001) en diastoliese bloeddruk (5.8%, p < 0.001). Daar was ook statisties betekenisvolle verbeteringe in relatiewe VO2maks en oefeningtoleransie na inoefening. Die opvolgtoetse na twee weke van geen-inoefening het getoon dat metaboliese aanpassings wat deur die HIIO bereik is, relatief blywend van aard was of ten minste nie totaal omgekeerd was nie. Die gewigsverlies wat deur die HIIO veroorsaak was is belangrik in die sin dat dit die hoofdoelwit aanspreek om die voorkoms van oorgewig en vetsugtigheid te verminder. Die studie suggereer verder dat 10 – 15 minute HIIO werksessies, by naby maksimale intensiteite, moontlik die minimum hoeveelheid inoefening is wat benodig word om betekenisvolle gewigsverlies en ander positiewe gesondheidskenmerke te bereik.

High intensity and / or exhaustive physical exercise may induce oxidative stress in athletes as well as in physically active or sedentary individuals. In this way the use of antioxidants appears as an alternative to prevent or mitigate this effect. Syzygium cumini (L.) Skeels, commonly known as jambolan, is a species found in tropical regions and is a species rich in phenolic compounds with potential antioxidant activity. The main objective of the study was to evaluate the effect of 21 days of supplementation with S. cumini hydroethanolic extract (EHE) in animals submitted to a protocol of 3 weeks of high intensity interval training (HIIT), 5 sessions per week. In this manner, wistar rats (250-300g) (CEPA: 58/2016) were used. The animals were randomly divided into 5 groups (n = 10): Sedentary (GC), sedentary animals treated with EHE (GEHE), animals submitted to high intensity interval training (HIIT) With EHE (GE + EHE) and animals submitted to (HIIT) and treated with quercetin (GE + Q). The results showed that EHE treatment was effective in reducing oxidative damage in the evaluated tissues: GT: 14.49 ± 1.78 vs GT + EHE: 8.16 ± 0.54 nmol EqMDA / mL of blood in the muscle ( GT: 9.61 ± 1.51 vs. GT + EHE 7.46 ± 0.69 nmol EqMDA / mg of liver), liver (GT: 40.85 ± 7.05 vs. GT + EHE: 19.97 ± 5, 95 nmol EqMDA / mg tissue) and heart (GT: 18.06 ± 2.88 vs. 12.64 ± 2.37 nmol EqMDA / mg tissue), while for the quantification of sulfhydryl groups the EHE treated animals had their Preserved thiols groups. Thus, it was concluded that daily treatment for 21 days with EHE was able to attenuate oxidative damage in wistar rats submitted to a HIIT protocol for 3 weeks. / O exercício físico de alta intensidade e/ou exaustivo, pode induzir o estresse oxidativo, tanto em atletas como em indivíduos fisicamente ativos ou sedentários. Desta forma o uso de antioxidantes surge como alternativa para prevenir ou atenuar esse efeito. A Syzygium cumini (L.) Skeels conhecida popularmente como jambolão, é uma espécie bastante encontrada em regiões de clima tropical, é uma espécie rica em compostos fenólicos com potencial atividade antioxidante. O Objetivo principal do estudo foi avaliar o efeito de 21 dias de suplementação com extrato hidroetanólico da S. Cumini (EHE) em animais submetidos a um protocolo de 3 semanas de treinamento intervalado de alta intensida (HIIT), 5 sessões por semana. Desta forma, foram utilizados ratos Wistar (250-300g) (CEPA: 58/2016). Os animais foram divididos aleatoriamente em 5 grupos (n=10): Sedentário (GC), sedentários tratados com EHE (GEHE), animais submetidos ao treinamento intervalado de alta intensidade (HIIT) (GE), animais submetidos ao (HIIT) e tratados com EHE (GE+EHE) e animais submetidos ao (HIIT) e tratados com quercetina (GE+Q). Os resultados demonstraram que o tratamento com EHE foi eficaz em reduzir o dano oxidativo nos tecidos avaliados: GT:14,49±1,78 vs GT+EHE: 8,16±0,54 nmol EqMDA/mL de sangue, no músculo (GT: 9,61±1,51 vs GT+EHE 7,46±0,69 nmol EqMDA/mg de técido), fígado (GT: 40,85±7,05 vs GT+EHE: 19,97±5,95 nmol EqMDA/mg de tecido) e coração (GT: 18,06±2,88 vs 12,64±2,37 nmol EqMDA/mg de tecido), enquanto para a quantificação de grupamentos sulfidrilas os animais tratados com EHE tiveram seus grupos tiois preservados. Desta maneira, conclui-se que o tratamento diário durante 21 dias com EHE foi capaz de atenuar o dano oxidativo em ratos wistar submetidos a um protocolo de HIIT durante 3 semanas. / São Cristóvão, SE

Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE / INTRODUCTION: Carbohydrate restriction have been currently pointed as the main strategy for weight loss and improvement of cardiometabolic health. However, it is not elucidated its real effect over cardiometabolic risk factors, due to the different levels of restriction and specially when associated with regular exercise practice. OBJECTIVE: This study aimed to propose a protocol of intervention for healthy weight loss and to evaluate its effect over the metabolic risk factors of overweight individuals. METHODS: The present study was a Randomized Controlled Trial of 12 weeks, with nutritional monitoring and diet with low carbohydrate (L-CHO – 100 g/d) or adequate carbohydrate (A-CHO – 250 g/d) amounts, associated to high intensity intermittent (HIIT) or continuous exercises. The study began with 106 overweight subjects, of wich 57 were allocated to the continuous exercise group and 49 were allocated to the HIIT group, distributed into two groups, according to the amount of carbohydrate. The subjects were assessed for weight, height, abdominal and hip circumference, in the baseline (M0) and after 12 weeks (M1). Thirty one volunteers ended the intervention in the HIIT group and their datum were analized for cardiometabolic risk factors changes after the intervention, based on their lipid markers, insulin and glucose levels. For the statistical analysis were apllyied two-way ANOVA with Bonferroni post-hoc and p<0,05 was considered significant. RESULTS: Both groups showed improvements in the antropometric variables. Regarding cardiometabolic risk factors, it was observed that there was an improvement for both groups, however, a significant increase in HDL-c was observed only in the A-CHO group (53,3 mg/dl – 60,1 mg/dl), while the LDL-c similarly decreased in both groups (A-CHO: 121,8 mg/dl – 97,4 mg/dl; R-CHO: 112,7 mg/dl – 94,9 mg/dl). A significant reduction in the number of risk factors associated with metabolic syndrome was observed, but the reduction in the prevalence of metabolically unhealthy individuals was more expressive among individuals in the A-CHO group. CONCLUSION: Thereby, It is concluded that both diets applied were efficient to guarantee improvement of body composition and weight loss. In addition, both diet strategies may be efficient to promote improvements in cardiometabolic risk parameters. However, the improvement in the protective factor (HDL) and the final risk classification indicated the adequacy of carbohydrates as the best strategy associated with caloric restriction and HIIT. / INTRODUÇÃO: Atualmente, uma das principais estratégias aplicadas para redução ponderal e melhora da condição cardiometabólica é a restrição de carboidratos da dieta. Porém, ainda não se encontra totalmente elucidado o real efeito desta restrição sobre a condição cardiometabólica, devido aos diversos níveis de restrição e principalmente quando se trata da associação com a prática de exercício físico de alta intensidade. OBJETIVO: Propor um protocolo de intervenção para perda de peso saudável e avaliar o seu efeito sobre os marcadores do risco cardiometabólico de indivíduos com excesso de peso. METODOLOGIA: Trata-se de um ensaio clínico controlado randomizado desenvolvido em 12 semanas de acompanhamento nutricional com dieta com baixo teor de carboidratos (R-CHO – 100 g/d) ou teor adequado deste nutriente (A-CHO – 250 g/d) associado ao treinamento intermitente (HIIT) ou contínuo. Iniciaram o estudo 106 indivíduos com excesso de peso, destes, 57 foram alocados no grupo de treinamento contínuo e 49 foram alocados no grupo HIIT, distribuidos em dois subgrupos, de acordo com o teor de carboidratos da dieta. Os indivíduos foram avaliados no período pré-intervenção (M0) e ao final das 12 semanas (M1). Foram aferidos peso, estatura, circunferências abdominal e do quadril. Para o artigo II desta dissertação, foram considerados os dados dos 49 voluntários alocados no grupo HIIT, onde finalizaram a intervenção 31 indivíduos. Este artigo propõe a avaliação do efeito da intervenção com dieta R-CHO e HIIT sobre o risco cardiometabólico dos participantes, avaliado com base nos marcadores lipidêmicos, insulinêmicos e glicêmicos. Para análise estatística foi aplicado o teste ANOVA two-way com post-hoc de Bonferroni, considerando significativo os valores de p<0,05. RESULTADOS: Ambos os grupos apresentaram melhora significativa das variáveis antropométricas. Já com relação aos marcadores de risco cardiometabólico, observou-se que houve melhora para ambos os grupos, no entanto, o aumento significativo do HDL-c foi observado apenas no grupo A-CHO (de 53,3 mg/dl para 60,1 mg/dl), enquanto que o LDL-c reduziu significativamente em ambos os grupos (A-CHO: de 121,8 mg/dl para 97,4 mg/dl; R-CHO: de 112,7 mg/dl para 94,9 mg/dl). Observou-se redução significativa do número de fatores de risco associados ao risco cardiometabólico, porém a redução da prevalência de indivíduos metabolicamente não saudáveis foi mais expressiva entre os indivíduos do grupo A-CHO (24,3%). CONCLUSÃO: Conclui-se que ambas as dietas foram eficientes na melhora da composição corporal e perda de peso. Ambas estratégias dietéticas podem ser eficientes para promover melhorias dos marcadores de risco cardiometabólico, porém, o aumento no fator de proteção (HDL) e na classificação final do risco apontou a adequação de carboidratos na dieta como melhor estratégia associada à restrição calórica e HIIT.

High-intensity interval training (HIIT) consists of short intervals of exercise at high intensity intermitted by intervals of lower intensity and is associated with improvement of body composition and metabolic health in adults. Studies in overweight adolescents are scarce. We conducted a randomized controlled trial in overweight adolescents to compare acceptance and attendance of HIIT with or without weekly motivational encouragement through text messages and access to a study website. HIIT was offered for six months (including summer vacation) twice a week (60 min/session). Participation rates were continuously assessed and acceptance was measured. Clinical parameters were assessed at baseline and after six months. Twenty-eight adolescents participated in this study (age 15.5 +/- 1.4; 54% female). The standard deviation score for body mass index over all participants was 2.33 at baseline and decreased by 0.026 (95% CI - 0.048 to 0.10) units, p = 0.49. Waist to height ratio was 0.596 at baseline and decreased by 0.013 (95% CI 0.0025 to 0.024), p = 0.023. Participation within the first two months ranged from 65% to 75%, but fell to 15% within the last three months. Attendance in the intervention group was 14% (95% CI - 8 to 37), p = 0.18, higher than the control group. Overall program content was rated as \"good\" by participants, although high drop-out rates were observed. Summer months constitute a serious problem regarding attendance. The use of media support has to be assessed further in appropriately powered trials.

The obesity epidemic is an important global health concern. Obesity is associated with a number of diseases including type 2 diabetes, non-alcoholic fatty liver disease (NAFLD), cardiovascular disease, and some cancers. Insulin resistance, a precursor to type 2 diabetes, is defined as an unresponsiveness of metabolic tissues to insulin, leading to long-term hyperglycemia and hyperinsulinemia. The fatty acid-induced model of insulin resistance indicates that an accumulation of lipid intermediates interferes with insulin signal transduction leading to insulin resistance. It is, therefore, important to examine means by which these lipid intermediates can be reduced to alleviate interferences in insulin signaling in the treatment of insulin resistance and type 2 diabetes. Exercise and metformin are two common interventions in patients with type 2 diabetes and obesity. They both commonly activate AMP-activated protein kinase (AMPK). AMPK contributes to a number of metabolic processes including increased glucose and fatty acid oxidation. However, the effects of AMPK activation on insulin sensitivity are currently not fully understood. This compilation of studies examined the insulin sensitizing effects of AMPK activation via metformin, exercise, and novel AMPK activator R419 in obese mice. In Chapter 2 we show that metformin increases AMPK phosphorylation of acetyl-CoA carboxylase (ACC) 1 Ser79 and ACC2 Ser212, resulting in increased fatty acid oxidation, decreased lipid content and improvements in hepatic insulin sensitivity. In Chapter 3 we show that exercise-induced improvements in insulin sensitivity occur independent of AMPK phosphorylation of ACC phosphorylation sites and independent of lipid content in the liver. Finally, in Chapter 4 we show that R419 improves skeletal muscle insulin sensitivity independent of AMPK and lipid content but improves exercise capacity via a skeletal muscle AMPK-dependent pathway in obese mice. These findings suggest that future studies examining the effects of AMPK activation in obesity will aid in our understanding of the mechanisms of insulin resistance and introduce methods of prevention and treatment of obesity and type 2 diabetes. / Thesis / Doctor of Philosophy (PhD)

Il est reconnu que les survivants d’accident vasculaire cérébral (AVC) présentent un important déconditionnement physique ainsi qu’une grande prévalence de comorbidités cardiovasculaires qui augmente considérablement le risque de subir un autre événement cardiovasculaire. En prévention secondaire, mis à part le traitement pharmacologique, il existe actuellement très peu de prise en charge de ces facteurs de risque lors de la phase de retour en communauté des patients. Pourtant, les lignes directrices recommandent l’activité physique de type aérobie comme moyen efficace de prévention cardiovasculaire. Par ailleurs, il existe de plus en plus de données probantes suggérant que l’entraînement par intervalles à haute intensité (HIIT) représenterait une forme d’exercice efficace pour améliorer la capacité cardiorespiratoire et le profil de santé chez différentes populations symptomatiques. La littérature demeure, toutefois, limitée quant à l’utilisation de cette méthode post-AVC. L’objectif général de cette thèse était de développer et d’évaluer un programme d’exercice incluant le HIIT en combinaison avec l’entraînement continu à intensité moyenne (MICT) pour les personnes ayant vécu un AVC ischémique ou une ischémie cérébrale transitoire (ICT) en prévention secondaire dans la phase chronique de la maladie. Les différentes étapes de cette recherche ont permis la rédaction de quatre articles scientifiques. Premièrement, la faisabilité et l’acceptabilité du protocole d’exercice élaboré incluant le HIIT ont été évaluées de façon favorable à la suite d’une intervention de trois mois. Cette première étude aura permis d’optimiser notre protocole pour développer les étapes subséquentes. En second lieu, l’efficacité du protocole lors d’une intervention de six mois a été évaluée dans une étude contrôlée randomisée en démontrant notamment une amélioration de la capacité cardiorespiratoire ainsi que des marqueurs d’anxiété et de dépression qui persistaient six mois après l’arrêt du programme supervisé comparativement à un groupe contrôle. Cette deuxième étude a également permis de comparer notre programme combiné contenant du HIIT à un programme d’activité physique standard comprenant seulement du MICT, sans toutefois démontrer aucune supériorité du protocole expérimental sur les variables cliniques mesurées. En troisième lieu, les réponses aiguës de la mesure ambulatoire de la pression artérielle à la suite d’un entraînement HIIT et à un iv entraînement MICT ont démontré un effet hypotenseur perdurant jusqu’à huit heures post-exercice, lequel était comparable pour les deux types d’entraînement. Finalement, une quatrième étude qualitative a permis de mettre en lumière une acceptabilité favorable des participants au programme comprenant du HIIT en plus de permettre de comprendre leur expérience afin de bonifier et d’optimiser des recherches futures. Cette thèse a contribué à l’avancement des connaissances en lien avec l’utilisation de la méthode HIIT chez les victimes d’AVC ischémique ou d’ICT dans la phase de réintégration et de maintien en communauté du continuum de soins post-AVC. Cette recherche a démontré un effet favorable sur des variables cliniques en plus d’avoir mis de l’avant l’acceptabilité positive du projet par les participants. Toutefois, les résultats ne supportent pas de supériorité d’inclure la méthode HIIT par rapport à l’utilisation du MICT seulement. Cette thèse soutient donc que l’ajout du HIIT pourrait être une alternative efficace dans un objectif de prévention secondaire en phase chronique de l’AVC ischémique et de l’ICT. Ce qui importe réellement est de rendre l’activité physique aérobie accessible, faisable et acceptable pour améliorer la santé et la qualité de vie des survivants d’AVC. / Stroke survivors have significant physical deconditioning and a high prevalence of cardiovascular comorbidities that significantly increase the risk of another cardiovascular event. In secondary prevention, apart from pharmacological treatment, there is currently little management of these risk factors during the phase of community reintegration. However, guidelines recommend aerobic exercise as an effective method of cardiovascular protection. In addition, there is growing evidence to suggest that high-intensity interval training (HIIT) is an effective form of exercise for improving cardiorespiratory fitness and health profile in different symptomatic populations. However, the literature remains limited on the use of this method post-stroke. The overall objective of this thesis was to develop et evaluate a realistic physical activity program including a combination of HIIT and moderate intensity continuous training (MICT) for people with ischemic stroke or transient ischemic attack (TIA) for secondary prevention in the chronic phase of the disease, thus addressing a clinical need. The different steps of this research led to the writing of four scientific articles. First, the feasibility and acceptability of the protocol developed were favorably evaluated following a three-month intervention. This first study allowed us to optimize our protocol to develop the subsequent steps. Secondly, the effectiveness of our protocol during a sixmonth intervention was evaluated in a randomized controlled study by demonstrating an improvement in cardiorespiratory capacity as well as markers of anxiety and depression that persisted six months after the program supervision was stopped compared to a control group. This second study also compared our program containing HIIT to a standard physical activity program with MICT without, however, showing any superiority of our combinated protocol on our variables. Third, the acute responses of ambulatory blood pressure measurement following HIIT training and MICT training demonstrated a hypotensive effect lasting up to eight hours post-exercise that was comparable for both types of intervention. Finally, a fourth qualitative study revealed a favorable acceptability of the participants to the combined program including HIIT and allowed us to understand their experience in order to improve and optimize future research. This thesis has contributed to the advancement of knowledge related to the use of HIIT post-stroke or TIA. Our research has demonstrated a positive effect on clinical variables and has highlighted the positive acceptability of the project by the participants. However, our results do not support a superiority of including the HIIT method over the use of MICT alone. This thesis therefore argues that the addition of HIIT could be an effective alternative in a secondary prevention goal in the chronic phase of ischemic stroke and TIA, but what really matters is making aerobic physical activity accessible to improve the health and quality of life of stroke survivors.

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Introduction: Crossfit is a modern sport that yearly expands worldwide. The goal of the sport is to develop performance and fitness so athletes can optimize their performance in many training categories. Furthermore, the sports WOD:s is complex, where many physiological challenges occur. The athlete is forced to push their limits of the movements, where there is a possibility for failure between the muscle fibers activation and synchronization. This can risk the sports security regarding injuries because of insufficient motor performance. A study from 2014 estimate the injury prevalence in crossfit to be 20%. Meanwhile a study from 2017 showed that the injury prevalence increased to 31,91%. Method: The objective of this study was to examine the crossfit athlete background, injury prevalence and injury categories between oktober 2016 - april 2017 in Sweden. A Brazilian survey was used in this study. The survey was modified and translated to Swedish before administered to certified crossfit facilities around the country. The method for this study used a descriptive cross-sectional design with a quantitative distribution of an online survey. Result: The common crossfit athlete is preferably 32 years or older, had a sedentary work and strict training routines with years of experience. Furthermore, 58 of 190 participants sustained a total of 87 injuries the past 6 month. This correlates to an injury prevalence of 30,5% for the crossfit athletes in Sweden. Furthermore, the most common injury categories were located on the neck/spine (21,84%), shoulder (18,39%), skeletal muscle (16,09%) and knee (16,09%). Therefore, the sport can cause different injuries throughout participation. Conclusion: Due to a high injury prevalence and a wide variation of injuries does the sport show a high injury risk, despite the athletes training experience. It takes more research to know the exact mechanisms for the injuries and how they can be prevented. / Introduktion: Crossfit är en nykommen sport somårligen växer världen över. Sporten syftar till att förbättra prestation och fitness i medvetenhet att optimera kompetens i alla fysiska kvalitéer. Dock finns det en komplexitet med att inkludera flera fysiska utmaningar i träningen. Utövaren tvingas utföra rörelserna med maximal insats för att inte misslycka samspelet mellan muskelfibrernas aktivering och synkronisering. Sådana misslyckanden kan äventyra säkerheten på grund av otillräcklig motorisk prestation. Studier från andra länder har uppmärksammat crossfitens skadeprevalens de senaste åren. Första studien från 2014 visar en prevalens på 20%, medan nyaste studien från 2017 visar en prevalens på 31,91%. Syfte: Denna studie har undersökt Sveriges crossfitutövares bakgrund, skadeprevalens och skadekategorier mellan oktober 2016 t.o.m. april 2017. Metod: Studien har använt en kvantitativ tvärsnittsstudie genom elektroniska enkäter. Enkäten har ursprung från en Brasiliansk studie som modifierades till svenska. Enkäten blev e-postad till Sveriges certifierade anläggningar i syfte att vidarebefordra enkäten till utövarna. Resultat: Studien bygger på 190 fullständiga enkätsvar som har generaliserats till Sveriges crossfitutövare. Resultatet visade att den generella crossfitutövaren ofta är över 32 år, har ett stillasittande yrke samt strikta träningsrutiner och många års träningserfarenheter, både inom och utanför crossfit. Skadeprevalensen visade att 30,5% av utövarna hade skadat sig de senaste 6 månaderna, då skadorna var lokaliserat på flera delar av kroppen. Vanligaste var nack-/rygg-(21,84%), axel-(18,39%), muskel-(16,09%) och knäskada (16,09%). Slutsats: Studien visade att Crossfitutgör en skaderisk trots erfaren träningsbakgrund. Men det krävs utförligare forskning för att kunna tyda de exakta mekanismerna för skadeuppkomsten. Det är viktigt att studier utförs för att förbättra sportens säkerhet eftersom anläggningar/organisationer ökar och forskning saknas.

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-04-27T15:00:50Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) mariana_aguiar_matos.pdf: 2901378 bytes, checksum: 40dbd704043d49a1eee587bb086c4eb4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-05-16T19:24:00Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) mariana_aguiar_matos.pdf: 2901378 bytes, checksum: 40dbd704043d49a1eee587bb086c4eb4 (MD5) / Made available in DSpace on 2017-05-16T19:24:00Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) mariana_aguiar_matos.pdf: 2901378 bytes, checksum: 40dbd704043d49a1eee587bb086c4eb4 (MD5) Previous issue date: 2016 / Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O excesso de gordura corporal caracter?stico da obesidade est? relacionado a diversas altera??es metab?licas, que incluem a resist?ncia ? insulina. Dentre as medidas n?o farmacol?gicas empregadas para a melhora da sensibilidade ? insulina est? o treinamento f?sico aer?bio, como o treinamento intervalado de alta intensidade (HIIT, do ingl?s high intensity interval training). Sendo assim, esse estudo avaliou os efeitos do HIIT em componentes bioqu?micos, celulares e moleculares relacionados ? resist?ncia ? insulina em obesos. Indiv?duos obesos sens?veis (n=9) e resistentes ? insulina (n=8) foram submetidos a 8 semanas de HIIT, em cicloerg?metro, realizado 3 vezes por semana, com intensidade e volume progressivos (8 a 12 est?mulos; 80 a 110% da pot?ncia m?xima). Amostras de sangue venoso e do m?sculo vasto lateral foram obtidas antes e ap?s o programa de HIIT. Ap?s o programa de treinamento houve aumento da sensibilidade ? insulina nos obesos resistentes ? insulina, mas n?o houve redu??o da massa de gordura. A concentra??o de citocinas no soro, o estresse oxidativo sist?mico e frequ?ncia das c?lulas imunes n?o foram modificadas ap?s o treinamento. No m?sculo esquel?tico, o HIIT promoveu aumento da fosforila??o do substrato do receptor de insulina (IRS) (Tyr612), da Akt (Ser473) e da prote?na quinase dependente de c?lcio/calmodulina (CAMKII) (Thr286), e aumento do conte?do da ?-hidroxiacil-CoA desidrogenase (?-HAD) e citocromo C oxidase (COX-IV). Houve ainda, redu??o da fosforila??o da quinase regulada por sinal extracelular (ERK1/2) nos obesos resistentes ? insulina. Conclu?mos que 8 semanas de HIIT promoveram melhora da sensibilidade ? insulina, modificou componentes da via de sinaliza??o da insulina e do metabolismo oxidativo no m?sculo esquel?tico. Essas altera??es ocorreram independentes de mudan?as na gordura corporal total e de par?metros inflamat?rios sist?micos. / Tese (Doutorado) ? Programa Multic?ntrico de P?s-Gradua??o em Ci?ncias Fisiol?gicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / Obesity is characterized by excess of body fat, and its development can lead to a variety of metabolic disorders, including insulin resistance. Exercise is recognized as a non-pharmacological approach to increasing skeletal muscle insulin sensitivity, although the mechanisms are not elucidated. Additionally, the understanding of high intensity interval training (HIIT, high intensity interval training) treat insulin resistance is less understood. Therefore, this study evaluated the effects of HIIT on biochemical, molecular, and cellular markers related to insulin resistance in sedentary obese individuals. Sensitive (n=9) and insulin resistant (n=8) obese individuals (body mass index ? 30 kg/m-2) were engaged in 8 weeks of HIIT using a cycle ergometer. The HIIT was performed 3 times a week, and its intensity and volume progressively increased throughout the training period (from 8 to 12 stimuli; from 80 to 110% of the maximum power). Venous blood and the vastus lateralis muscle samples were obtained before and after the HIIT. HIIT enhanced insulin sensitivity in insulin-resistant obese individuals without changing body fat mass. Cytokine concentration in serum, blood oxidative stress, and frequency of some immune cells were not altered by HIIT. In skeletal muscle, HIIT increased the phosphorylation of insulin receptor substrate (IRS) (Tyr612), Akt (Ser473), and protein kinase dependent calcium/calmodulin (CaMKII) (Thr286). HIIT also increased the expression of ?-hydroxyacyl-CoA dehydrogenase (?-HAD) and cytochrome C oxidase (COX-IV). A reduction of the kinase phosphorylation of extracellular signal-regulated (ERK1/2) was only seen in obese insulin resistant individuals. The results show that 8 weeks of HIIT enhanced insulin sensitivity, modified components of the insulin-signaling pathway, and improved skeletal muscle oxidative metabolism. These changes were independent of alterations in body fat and inflammatory parameters.

This study investigated the effects of high intensity interval training (HIIT) and β-hydroxy-β-methylbutyric free acid (HMBFA) on the onset of neuromuscular fatigue in healthy young men and women. Thirty-seven subjects (22 men and 15 women; mean ± SD age = 22.8 ± 3.4yrs) completed an incremental cycle ergometer test (GXT) to exhaustion. During the GXT, electromyography (EMG) signals from the right vastus lateralis were recorded to determine the power output at the onset of neuromuscular fatigue (PWCFT), and peak wattage was used to assign individual training loads. After baseline testing (PRE), subjects were randomly assigned to one of three groups: control (C, n = 9), training with placebo (P, n = 14), or training with supplementation (S, n = 14). Subjects assigned to P and S completed 12 HIIT sessions over 4 weeks while subjects assigned to C were asked to maintain their normal diet and activity patterns. After 4 weeks, subjects returned for post-testing (POST). The PWCFT values (W) were determined using a DMAX method. The EMG amplitude root mean square (µVrms) values were used to generate a third-order polynomial regression (3PR) representing the increase in µVrms versus time of the GXT. The onset of fatigue (TF) was defined as the x-value (time, s) of the point on the 3PR that measured the maximal perpendicular distance from the line between the first and last data points. TF was used to estimate PWCFT according to the equation: PWCFT = PO + a · (n/N), where PO is the power output of the stage in which TF occurred, a is the increment in power output between GXT stages (25W), n is the difference (s) between TF and the beginning of the stage during which TF occurred, and N is the duration of a stage (120s). A two-way repeated measures ANOVA was used to identify group × time interaction for PWCFT. If a significant interaction occurred, one-way factorial ANOVAs were used. Fisher's least significant difference post hoc comparisons were performed between groups. If a significant main effect occurred, dependent samples t-tests with Bonferroni corrections (p = [0.05/3] = 0.017) were performed across time for each group. The two-way ANOVA resulted in a significant interaction (F = 6.69, p = 0.004). Follow-up analysis with one-way ANOVA resulted in no difference among groups at PRE (F = 0.87, p = 0.43), however a significant difference was shown for POST values (F = 5.46, p = 0.009). Post-hoc analysis among POST values showed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes following HIIT for S (p < 0.001) and P (p = 0.016), but no change in C (p = 0.473). Results of this study indicate that HIIT was effective in delaying the onset of fatigue, but supplementation with HMBFA in conjunction with HIIT was more effective than HIIT alone. An increase in PWCFT represents an increase in the maximal power output an individual can sustain without eliciting fatigue. Therefore, HIIT can be used to improve performance in both endurance activities as well as intermittent sports. In addition, HMBFA supplementation is a simple method that can be used to maximize the benefits of HIIT. Acknowledgments: Metabolic Technologies, Inc. provided the supplement and funding for this study.