In light of the current global prevalence of overweight and obesity, the associated health risks, and the continuing adoption of sedentary lifestyle, this thesis investigated some of the factors that contribute to exercise adherence, directly comparing high-intensity whole body interval training and continuous endurance training. 68 inactive university aged adults (Age: 21.4±3.4 yrs, BMI: 25.6±4.6 kg/m2, VO2peak 40.1±5.7 ml/kg/min) were randomized into one of three groups; a non-exercise control, whole body high intensity training, or continuous endurance training. Aerobic capacity measurements, time to completion trials, muscular endurance, and core strength measures were taken at pre, post and follow up testing sessions. Psychological questionnaires were also administered during exercise as well as throughout the study. Following the intervention both exercise groups demonstrated equivalent improvements in aerobic performance, with only the interval group experiencing improved muscular and core endurance. After the 2-month follow up testing sessions the interval group lost all aerobic and core adaptation, with endurance only experiencing a partial loss. This finding indicates that the interval group did not adhere to exercise at a level that was high enough to preserve the adaptations associated with training. This finding is further supported by the psychological factors measured throughout this study, including acute affect, enjoyment and intentions to engage in future exercise. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2013-10-31 15:08:15.524

Master of Science / Department of Kinesiology / Craig A. Harms / High-intensity interval training (HIT) has been utilized as a time-efficient strategy to induce numerous physiological adaptations and improve performance usually associated with “traditional” endurance training (ET). It is not known however, if HIT might lead to improvements in pulmonary function. Therefore we hypothesized that HIT would increase respiratory muscle strength and expiratory flow rates. Fifteen healthy subjects were randomly assigned to an ET group (n = 7) and a HIT group (n = 8). All subjects performed an incremental test to exhaustion (VO2 max) on a cycle ergometer prior to and after training. Standard pulmonary function tests, maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), and maximal flow volume loops, were performed pre training and after each week of training. HIT subjects performed a four week training program on a cycle ergometer at 90% of their VO2 max final workload while the ET subjects performed exercise at 60-70% of their VO2 max final workload. All subjects trained three days/ week. The HIT group performed five one-minute bouts with three minute recovery periods and the ET group cycled for 45 minutes continuously at a constant workload. A five-mile time trial was performed prior to training, after two weeks of training, and after four weeks of training. Both groups showed similar (p<0.05) increases in VO2 max (~8-10%) and improvements in time trials following training (HIT 6.5 ± 1.3%, ET 4.4 ± 1.8%) with no difference (p>0.05) between groups. Both groups increased (p<0.05) PImax post training (ET ~25%, HIT ~43%) with values significantly higher for HIT than ET. There was no change (p>0.05) in expiratory flow rates with training in either group. These data suggest that whole body exercise training is effective in increasing inspiratory muscle strength with HIT leading to greater improvements than ET. Also, HIT offers a time-efficient alternative to ET in improving aerobic capacity and performance.

Master of Science / Department of Kinesiology / Craig A. Harms / Subjects with prehypertension are at risk for developing hypertension (HTN). Hypertension is associated with low-grade systemic inflammation (LGSI). Aerobic exercise training (ET) is a proven means to reduce both blood pressure and LGSI in healthy and diseased subjects. Recently, high intensity interval training (HIIT) has been show to elicit similar cardiovascular and metabolic adaptations as ET in healthy and at-risk populations in a more time efficient manner. Therefore, we hypothesized that HIIT would elicit greater reductions in blood pressure and LGSI than ET. Twelve pre-hypertensive subjects (systolic blood pressure 127.0 ± 8.5 mmHg; diastolic blood pressure 86.2 ± 4.1 mmHg) were randomly assigned to an ET group (n=5) and a HIIT group (n=7). All subjects performed an incremental test to exhaustion (VO2max) on a cycle ergometer prior to, after 4 weeks, and after 8 weeks of training. Resting heart rate and blood pressure were measured prior to and three times a week during training. LGSI was measured via high-sensitivity C-reactive protein (hs-CRP) prior to, after 4 weeks and after 8 weeks of training. ET subjects performed an eight week exercise training program at 40% VO2 reserve determined from the VO2max test, while HIIT subjects performed exercise at 60% peak power determined from the VO2max test. ET group trained four days/week while HIIT trained three days/week. ET exercised for 30 minutes continuously at a constant workload and cadence of 60 rpm while HIIT performed a protocol on a 1:1 work-to-rest ratio at a constant workload and cadence of 100 rpm. Both groups showed similar (p<0.05) decreases in mean arterial (ET = -7.3%, HIIT = -4.5%), systolic (ET = -6.6%, HIIT = -8.8%), and diastolic (ET= -9.7, HIIT= -8.2%) blood pressure. HIIT decreased in LGSI (-33.7%) while ET did not change LGSI (p>0.05). VO2max increased ~25% with both HIIT and ET with no differences (p>0.05) between groups. These data suggest both HIIT and ET similarly decreased resting blood pressure and increased VO2max while HIIT was effective in decreasing LGSI in subjects who were pre-hypertensive.

In recent years there has been a surge in interest concerning high intensity intermittent exercise training (HIT) due to its ability to confer rapid notable cardio-metabolic health benefits. Specifically, HIT has been shown to improve insulin sensitivity and glycaemic control as well as other cardiovascular health factors after just 2 weeks of training (typically 6 training sessions). This thesis investigated the potential therapeutic role of HIT training within obese cohorts specifically addressing metabolic health, inclusive of inflammatory profiles and glycaemic control.

Although there is an abundance of research investigating the effects of exercise on cognitive function, few studies have investigated acute effects of exercise on performance of tasks involving executive function. Furthermore, the effects of different exercise intensities on multiple tests of executive function have received little attention. The purpose of this study was to examine the acute effects of 20-minutes of stationary cycling exercise at varying exercise intensities on executive function performance and to determine these acute effects immediately following exercise as well as after 10 and 30-minute delays following exercise. University students (N = 88) completed baseline measures of executive function (stop-signal task [SST] and Stroop task [ST]) and a graded cardiovascular exercise test on Visit 1. On Visit 2, participants were stratified by gender and fitness level and randomized to one of four conditions: high-intensity interval training (HIT), high, moderate or low-intensity steady-state exercise performed on a cycle ergometer. The ST and SST were performed immediately following exercise and again at 10- and 30-minutes post-exercise. Immediately following exercise, ST response times were significantly different (p < .05), demonstrating faster response times for the high and moderate intensity exercise (p < .05), while improvements in SST response inhibition were revealed for the HIT (p < .01) condition. At 10-minutes post-exercise, moderate and low-intensity conditions revealed improvements in ST response times (p <.05), with enhanced SST response inhibition evident in the HIT, moderate and low-intensity conditions (p < .05). At 30-minutes post-exercise, ST response times continued to show improvements from baseline for the moderate and low-intensity conditions (p < .05), while SST response inhibition trended back towards baseline levels (p > .05). The present outcomes demonstrate beneficial effects of exercise, regardless of intensity, for up to 38 minutes post-exercise. Future research should focus on mechanisms that would account for these effects and factors that support enhanced executive function performance with exercise training. / Thesis / Master of Science (MSc)

abstract: The winter holiday period has been highlighted as a major risk period for weight gain due to excess caloric intake in the form of fat and sugar. Furthermore, diets high in fat and sugar have been implicated in the pathogenesis of diabetes and cardiovascular disease. Exercise aids in the prevention of weight/fat gain, and prevents deleterious changes in cardiometabolic function. The objective of this study was to examine the effects of a fat-sugar supplemented diet, with and without two different exercise training protocols, on body composition, glycemic control and other markers of cardiovascular disease in an at-risk population of overweight and obese males. Twenty-seven, healthy overweight/obese (BMI >25 kg/m2) males were fed 2 donuts per day, 6 days/week, for four weeks, while maintaining their current diet. In addition, all subjects were randomized to one of the following conditions: sedentary control, 1,000 kcal/week moderate-intensity continuous training (MICT) (50% of peak oxygen consumption), or 1,000 kcal/week high-intensity interval training (HIIT) (90-95% of peak heart rate). Supervised exercise training was performed 4 days/week on a cycle ergometer. Changes in body weight and composition, endothelial function, arterial stiffness, glycemic control, blood lipids and cardiorespiratory fitness (CRF) were assessed before and after the intervention. Body weight, lean mass and visceral fat increased significantly in HIIT (p<0.05) and were unchanged in MICT. There was a trend for a significant increase in body weight (p=0.07) and lean mass (p=0.11) in control. Glycemic control during the 2-h OGTT improved significantly in MICT and control, with no change in HIIT. Hepatic insulin resistance index (IRI) and 30-min insulin during the OGTT improved significantly after MICT and worsened following control (p=0.03), while HIIT was unchanged. CRF increased significantly in both HIIT and MICT, with no change in control (p<0.001). There were no significant changes in other markers of cardiovascular disease. The addition of a fat-sugar supplement (~14,500 kcal) over a 4-week period was not sufficient to induce deleterious changes in body composition and cardiometabolic health in overweight/obese young males. Exercise training did not afford overweight/obese males additional health benefits, with the exception of improvements in fitness and hepatic IRI. / Dissertation/Thesis / Doctoral Dissertation Physical Activity, Nutrition and Wellness 2016

L’exercice fractionné de haute intensité (HIIT) et continu d’intensité modéré (MOD) représentent les 2 grandes modalités d'endurance. Cependant, leur impact spécifique sur la performance physique et la plasticité cérébrale et musculaire reste controversé du fait de la diversité des protocoles d’exercice proposés chez les sédentaires. Notre 1er axe dégage chez des rats sains l’effet de ces 2 modalités sur la performance physique, la plasticité musculaire et cérébrale sur 8 semaines d’entrainement standardisée dont l'intensité est basées sur le seuil lactique. Nos résultats montrent des gains de performance d’endurance plus rapides et importants suite aux HIIT. La neuroplasticité serait stimulée par les HIIT uniquement et la plasticité musculaire semble spécifique à chacune. L’engouement pour les HIIT se répercute chez les patients subissant un accident vasculaire cérébral où l’efficacité des méthodes d’endurance n’est pas clairement justifiées. Une étude antérieure a montré l’intérêt majeur des HIIT dans la phase aiguë de la pathologie malgré une récupération sensorimotrice incomplète. D’où l’intérêt d’approfondir dans notre second axe l’effet des différentes formes de HIIT (longs et courts) dans la récupération. Nos résultats montrent principalement que ces deux formes de HIIT améliorent la capacité d’endurance et la force de la patte antérieure lésée avec une précocité pour les HIIT longs. Les deux formes de HIIT semblent induire une angiogenèse cérébrale. Néanmoins, ils n’améliorent pas les fonctions sensorimotrices et cognitives. Ainsi, il est nécessaire d’approfondir les répercussions de ces deux entrainements HIIT dans la plasticité musculaire et cérébrale. / Endurance exercise is essential for different reasons in athlete and also in aging and pathological people. Two training modalities were found: high intensity interval training (HIIT) and moderate intensity aerobic training (MOD). However, the specific outcomes of these modalities on physical performance and cerebral and muscular plasticity are controversial because many exercise protocols exist. The 1st study explore the impact of these 2 training on endurance and functional capacity and also on muscular and cerebral molecular modifications throughout 8 weeks in healthy rats. HIIT and MOD programs are work-matched and training intensity are determined thanks to the lactate threshold. Our results show a superior and fast effect on endurance capacity after HIIT compared to MOD. Hippocampal plasticity is stimulated only after HIIT and muscular modifications appear to be specific to each modality. A great interest of HIIT is found in stroke patients for whom evidence of endurance modalities efficiency is still missing. A previous study has shown a beneficial effect of HIIT in the acute phase of stroke despite incomplete sensorimotor recuperation. Hence, the interest to deepen in second part of this manuscript the impact of two HIIT modalities (short and long) in recovery optimisation. Our results show that 2 HIIT strongly improve endurance performance and strength of injured paw with a fast effect for long HIIT. The 2 modalities seem to induce cerebral angiogenesis. However, these 2 training do not increase sensorimotor and cognitive functions. In perspective, it appears necessary to develop muscular and cerebral outcomes induced by these 2 HIIT modalities.

Whilst high levels of cardiorespiratory fitness and physical activity may protect against cardiometabolic risk factor clustering, evidence suggests these outcomes are below optimal in English youths. Adolescence is a key stage in health behaviours development, and thus represents an opportunity for interventions aiming to improve the cardiometabolic health, fitness and activity levels of this population. Recently, there has been growing interest in the efficacy of low-volume high-intensity interval training (HIT) as a time efficient way of improving health and fitness outcomes in adults. Contrastingly, the effects of low-volume HIT in adolescents remains relatively unknown. The first aim of this programme therefore was to develop a novel school-based low-volume HIT intervention. The second was to determine the effectiveness of this model for improving the cardiometabolic health, cardiorespiratory fitness and physical activity levels of adolescents. Study one examined adolescents’ views towards high-intensity exercise, and the proposed low-volume HIT intervention. This data was used to design the novel low-volume HIT model. In Study 2, participants’ heart rate and perceived exertion responses to three prototype prescriptions of low-volume HIT, based on boxing, dance and football were examined. Here, it was indicated that these activities were capable of eliciting a high-intensity training response (~90% of maximum heart rate). Study 3 incorporated the main intervention, which examined the effect of a 10-week multi-activity low-volume HIT intervention (named Project FFAB [Fun Fast Activity Blasts]) on various health and fitness outcomes in adolescents. Here, beneficial effects were detected in the intervention participants compared to the controls for triglycerides, waist circumference, lipid accumulation product and daily moderate-to-vigorous physical activity. Study 4 assessed the fidelity of the intervention, and found that this had been largely upheld. Collectively therefore, it appears that Project FFAB represents a viable strategy for improving aspects of cardiometabolic health and physical activity levels in adolescents.

The IL-6 system is key in the development of chronic low-grade inflammation. It is known to be upregulated in response to acute exercise and lowered at rest after exercise training. IL-6 has both anti- and pro-inflammatory properties and moderation of this cytokine could alleviate chronic low-grade inflammation which is associated with obesity and Type 2 diabetes mellitus (T2DM). This thesis investigated the interplay between inflammation, glycaemic control and high intensity intermittent training (HIIT) - an exercise regimen that has been shown to yield many health benefits. There was a greater increase in IL-6 after an acute bout of HIIT than continuous moderate intensity exercise, where external work was matched (Chapter 4). Although sIL-6R and the IL-6/sIL-6R complex were both significantly increased after acute exercise there were no differences between HIIT and moderate intensity exercise. In response to 2 weeks HIIT there was a significant reduction in IL-6 and increase in IL-6R in adipose tissue in overweight and obese males (Chapter 5). It was also determined that IL-6R present in adipose tissue is at least partly composed of the membrane-bound IL-6R isoform (Chapter 6). Reductions in circulating sIL-6R, the IL-6/sIL-6R complex, MCP-1 and adiponectin, as well as a decrease in waist circumference and increase in peak oxygen uptake during exercise were also induced after 2 weeks HIIT (Chapter 5). Young adults with T2DM (< 40 y) displayed elevated levels of inflammatory proteins in comparison to lean controls, however there were no significant differences in comparison to obese controls (Chapter 7). In conclusion, the findings of this thesis demonstrate that acute and repeated bouts of HIIT have positive effects on the inflammatory profile in the circulation and adipose tissue, particularly in relation to the IL-6 system. It should be determined if HIIT is an achievable mode of exercise for patient populations, including T2DM patients, in order to downregulate the inflammatory profile.

A síndrome metabólica (SM) é uma somatória de fatores de risco para desenvolvimento de doenças cardiovasculares (DCV), intimamente ligada à obesidade e, assim como a última, sua prevalência cresce mundialmente. Sua etiologia é complexa e suas causas são influenciadas por fatores ambientais e genéticos. Sabe-se que a elevação da capacidade cardiorrespiratória (VO2máx) seja um melhor atenuador do risco de mortalidade por DCV do que a própria obesidade. Atualmente a forma conhecida para aumento do VO2máx é o exercício físico aeróbio, porém vários indivíduos reportam falta de tempo para realização de uma rotina de exercícios físicos. Neste contexto, o presente trabalho teve como objetivo comparar dois protocolos de treinamento aeróbio de alta intensidade e outro contínuo de moderada intensidade quanto à influência na capacidade cardiorrespiratória, variáveis de síndrome metabólica (circunferência da cintura - CC, glicemia de jejum, HDL, triglicérides e pressão arterial) e composição corporal (massa e percentual de gordura) em indivíduos com sobrepeso/obesidade e; observar a influência de polimorfismos dos genes visfatina e receptor tipo 1 de angiotensina 2 (AGTR1) nos níveis de glicemia, HDL, triglicérides e pressão arterial. 40 indivíduos foram divididos aleatoriamente em três grupos de treinamento: contínuo moderado (CM), 4x1 e 4x4. O grupo CM realizou cinco sessões semanais de treino por 30 minutos; os grupos 4x1 e 4x4 realizaram 3 sessões semanais com duração de 19 e 40 minutos, respectivamente. A intervenção durou 16 semanas e as sessões foram monitoradas quanto à frequência cardíaca para controlar a intensidade do exercício. O grupo CM se exercitou a 70% da frequência cardíaca máxima, enquanto os grupos 4x1 e 4x4 realizaram estímulos a 90% da frequência cardíaca máxima. Os resultados encontrados apontaram uma melhora na capacidade cardiorrespiratória em todos os grupos, sem diferença entre eles. Diminuição da massa corpórea, IMC, percentual de gordura somente no grupo 4x4. Diminuição de CC nos grupos 4x4 e CM. Os dados da análise genética não apontaram nenhuma relação entre os polimorfismos avaliados e as variáveis de interesse. Por fim, concluiu-se que o treinamento de alta intensidade com duração de 19 minutos promove resultados semelhantes ao treinamento de mesma intensidade e duração de 40 minutos e ao treinamento de intensidade moderada na capacidade cardiorrespiratória em indivíduos com sobrepeso/obesidade, sendo uma alternativa viável para treinamento físico com pouco volume. / Metabolic syndrome (MS) is a sum of risk factors for developing cardiovascular disease (CVD), closely linked to obesity and, like the latter, its prevalence is growing worldwide. Its etiology is complex and its causes are influenced by environmental and genetic factors. It is known that the increase in cardiorespiratory fitness (VO2max) is a better attenuator of CVD mortality risk rather than obesity itself. Currently, the best known way to increase VO2max is aerobic exercise, but many people report lack of time to perform a exercise routine exercise. In this context, this study aimed to compare two high intensity aerobic exercise protocols and a continuous moderate exercise regarding their effects on cardiorespiratory fitness, metabolic syndrome variables (waist circumference - WC, fasting plasma glucose, HDL, triglycerides, and blood pressure) and body composition (body mass and fat percentage) in overweight/obese individuals and; observe the influence of genetic polymorphisms of visfatin and angiotensin 2 receptor type 1(AGTR1) in blood glucose levels, HDL, triglycerides and blood pressure. 40 subjects were randomly divided into three training groups: continuous moderate intensity (CM), 4x1 and 4x4. The CM group held five weekly training sessions for 30 minutes; the 4x1 and 4x4 groups performed three weekly sessions lasting 19 and 40 minutes, respectively. The intervention lasted 16 weeks and the sessions were monitored for heart rate to control the exercise intensity. The CM group exercised at 70% of maximum heart rate, while the 4x1 and 4x4 groups performed stimuli to 90% of maximum heart rate. The findings showed an improvement in cardiorespiratory fitness in all groups, with no difference between them. A decreased body mass, BMI, body fat percentage only in the group 4x4. WC decrease in 4x4 and CM groups. Data from genetic analysis did not show any relationship between the evaluated polymorphisms and the variables of interest. Finally, it was concluded that the high intensity training lasting 19 minutes promotes similar results to the training of the same intensity and duration of 40 minutes and moderate intensity training on cardiorespiratory fitness in overweight/obese individuals, being a viable alternative for exercise training with low volume.