Vascular dysfunction in obesity: beneficial effects of aerobic exercise training in animal models

Abstract Cardiovascular disease (CVD) is the leading cause of mortality in the world and several risk factors for developing CVD have been pointed out, including obesity and physical inactivity. Endothelial dysfunction as a consequence of metabolic and inflammatory disorders plays an important role in the onset of vascular complications in obesity. In addition, it is well established that aerobic exercises promote beneficial effects on CVD by increasing nitric oxide (NO) production or its bioavailability in human and experimental models. The interest in exercise studies increased significantly, with promising results. Considering the importance of this field, the purpose of this mini-review is to summarize the animal studies that investigated the physiological mechanisms of vascular dysfunction in obesity and how aerobic exercise training influenced these alterations.(AU)

Aerobic exercise training induces superior cardioprotection following myocardial ischemia reperfusion injury than a single aerobic exercise session in rats

Abstract AIM To compare the amount of cardioprotection induced by a single exercise session with those achieved after an 8-week aerobic exercise training following ischemia reperfusion injury in rats. METHODS Twenty-five male Wistar rats (250-300g) were assigned into a group submitted to physical training (TR; n=12) or a single maximal exercise session (EXE; n=13). Following sedentarism or physical training (8 weeks, 5 sessions/wk, 1h/session at 70% of maximal speed) both groups performed a maximal exercise test. Then, groups were submitted to ischemia reperfusion injury (30 min/1h) through an isolated heart protocol, in which left ventricle developed pressure was measured. RESULTS The TR group presented greater maximal oxygen consumption compared to the EXE group (77.25±20.41 vs 41.32±25.86 ml/Kg/min; P=0.003). Regarding left ventricle developed pressure, no differences were detected between groups at baseline (TR: 89.78±24.40 vs EXE: 81.37±31.84 mmHg; P=0.48). However, after reperfusion, the TR group presented superior intraventricular pressure than EXE group (37.94±18.34 vs 21.59±13.67 mmHg; P=0.03). CONCLUSION Eight-week aerobic training induced greater cardioprotection against ischemia reperfusion injury in rats compared to a single exercise session, due to an increased cardiac function. This suggests that exercise-induced cardioprotection is a multifactorial process that may involve different mediators according to the exercise duration.(AU)

Advance in Cardiorespiratory Fitness after Stroke(review) / 中国康复理论与实践

Cardiorespiratory fitness(CRF)descends after stroke because of hemiplegia and adaption of insulin,musculoskeletal,cardio-vascular and respiratory system.Aerobic exercise training can improve CRF of individuals with stroke, while robotic-assisted exercise is probably safety and effectiveness for patients with severe stroke or patients within one week after stroke.

7-week aerobic exercise training reduces adipocyte area and improves insulin sensitivity in wistar rats fed a highly palatable diet

The aim of this study was to evaluate the effect aerobic exercise training on fat pad mass, adipocyte size, leptin release and insulin sensitivity in rats fed with high fat-palatable diet. Twenty-four male Wistar rats (250-260g) were divided into four groups: sedentary control (CTR/SD), trained control (CTR/TR), obese sedentary (OB/SD) and obese trained (OB/TR). Obese groups were fed with high fat-palatable diet (27% of fat) and control groups fed with AIN-93. Our results showed that aerobic exercise training was effective to reduce body weight and epididymal fat mass in CTR/TR and OB/TR. Insulin and glucose levels were increased in OB/TR compared with OB/SD. Aerobic exercise training reduced the average area of adipocytes in CTR/TR and OB/TR and it was associated with reduced plasma insulin and leptin. In conclusion, 7-week aerobic exercise training reduces adipocyte area and improves insulin sensitivity and leptin levels in high fat-palatable diet-fed Wistar rats.

Mecanismos associados ao desenvolvimento das complicações cardiometabólicas em SHR submetidos à sobrecarga de frutose: papel do treinamento físico aeróbio / Mechanisms associated with cardiometabolic dysfunctions development in SHR submitted to fructose overload: role of aerobic exercise training

Neste estudo testamos a hipótese que alterações no controle autonômico precedem alterações cardiometabólicas em animais espontaneamente hipertensos tratados com frutose (SHR). Adicionalmente avaliamos os efeitos do treinamento físico aeróbio (TFA) no curso temporal das disfunções observadas neste modelo de síndrome metabólica. Para isso, foram utilizados ratos machos Wistar e SHR divididos em grupos (n=8): Controle (C), Hipertenso (H), Hipertenso+Frutose (HF) e Hipertenso+Frutose+Treinamento Físico (HFT). A sobrecarga de frutose (100g/L) e o TFA (esteira: 1h/d., 5d/sem.) foram iniciados 30 dias após o nascimento dos animais. Os grupos experimentais foram divididos em subgrupos que foram avaliados após 7, 15, 30 e 60 dias de protocolo. A partir dos 7 dias de protocolo a associação da hipertensão ao consumo de frutose (grupo HF) induziu redução da sensibilidade barorreflexa para respostas bradicárdicas (RB) e taquicárdicas (RT) em comparação ao grupo C; observando-se redução adicional da RB no grupo HF em relação ao grupo H (7 dias: -40% e 15 dias: -36%). A reatividade vascular à fenilefrina (8ug/ml: 7 aos 60 dias) estava prejudicada nos grupos H e HF em relação ao C; com prejuízo adicional do grupo HF ao nitroprussiato de sódio na dose de 20ug/ml (15 aos 60 dias de protocolo vs. C). Além disso, aos 15 e 30 dias de protocolo, o grupo HF apresentou um aumento marcante do TNFalfa e IL-6 no tecido adiposo e de IL-1beta no baço em relação aos grupos C e H. Houve redução de nitritos plasmáticos no grupo HF em 15 (55%) e 30 dias (58%) vs. o grupo C, acompanhado de aumento do peróxido de hidrogênio em 30 dias vs. o grupo H (98%). Em relação as defesas antioxidantes, o grupo HF apresentou menor atividade da superóxido dismutase (SOD) vs. os grupos C (15 dias: 36%, 30 dias: 31% e 60 dias: 47%) e H (15 dias: 25%, 30 dias: 21% e 60 dias: 43%), sem alterações significantes na catalase e no potencial antioxidante total. O grupo HF teve maior lipoperoxidação e oxidação de...

This study tested the hypothesis that changes in autonomic control precede cardiometabolic changes in spontaneously hypertensive rats (SHR) treated with fructose. Additionally, the effects of aerobic exercise training (AET) were evaluated in the time course of the dysfunctions observed in this metabolic syndrome model. Wistar and SHR rats were divided into groups (n=8/group): control (C), hypertensive (H), hypertensive + fructose (HF) and hypertensive + fructose + AET (HFT). The fructose overload (100g/l) and the AET (treadmill 1h/d, 5d/wk) was initiated at 30 days of life. The experimental groups were divided into subgroups, which were evaluated after 7, 15, 30 and 60 days of protocol. Since 7 day of protocol the association of hypertension and fructose consumption (HF group) induced a reduction in baroreflex sensitivity for bradycardic (BR) and tachycardia responses (TR) when compared to the C group; there was an additional reduction of BR in the HF group when compared to the H group (7 days: 40% and 15 days: 36%). The vascular reactivity to phenylephrine (8ug/ml: 7 to 60 days) was impaired in H and HF groups when compared to the C group; it was observed an additional impairment in the HF group to sodium nitroprusside at the dose of 20?g/ml (15 to 60 days of protocol vs. C). Additionally, at 15 and 30 day of protocol, the HF group showed an increase in TNFalfa and IL-6 in adipose tissue and in IL-1beta in the spleen when compared to C and H groups. There was a reduction in plasma nitrites in the HF group in 15 (55%) and 30 days of protocol (58%) vs. the C group, accompanied by an increase of the hydrogen peroxide in 30 days vs. H group (98%). Regarding the antioxidant defenses, the HF group showed reduced superoxide dismutase (SOD) activity as compared to C (15 days: 36%, 30 days: 31% and 60 days: 47%) and H groups (15 days: 25% 30 days: 21% and 60 days: 43%), without significant changes in catalase and in total antioxidant potential. The HF group had...

Treinamento físico aeróbio previne à hipertrofia cardíaca patológica e melhora a função diastólica em ratos Zucker obesos / Aerobic exercise training revert pathologic cardiac hypertrophy and improves the diastolic function in obese Zucker rats

A obesidade é uma patologia diretamente relacionada com o desenvolvimento de doenças cardiovasculares. Por outro lado, o treinamento físico aeróbio atenua o desenvolvimento da obesidade e promove benefícios cardíacos em obesos. Dessa forma, nosso objetivo foi investigar se a obesidade altera a função cardíaca e se sua associação com o treinamento físico aeróbio promove melhora na função cardíaca em ratos Zucker obesos. Os ratos Zucker foram divididos da seguinte forma: grupo magro (GM), grupo obeso (GO), grupo magro treinado (GMTR) e grupo obeso treinado (GOTR). O protocolo de treinamento aeróbio de natação foi realizado por um período de 10 semanas com cinco sessões semanais de 60 minutos de duração. A frequência cardíaca de repouso, a pressão arterial sistólica, a hipertrofia e função cardíaca foram avaliadas no final do período de treinamento físico. Ambos os grupos treinados apresentaram uma queda de 12 por cento da frequência cardíaca de repouso, quando comparado com seus respectivos controles. Ainda, nossos resultados demonstraram que o treinamento aeróbio reduziu o aumento da massa cardíaca em 13 por cento e melhorou a função diastólica na obesidade em 43 por cento. Em conclusão, nossos dados demonstraram que o treinamento físico aeróbio reverteu os prejuízos cardíacos causados pela obesidade.

Obesity is profoundly involved in cardiovascular diseases. On the other hand, aerobic exercise training (EXT) attenuates obesity and promotes cardiac benefits in obese individuals. Therefore, the aim of this study was to investigate if obesity alters the cardiac function and whether its association with exercise training can improve cardiac function in an obese Zucker rat strain. The rats were divided in the following groups: Lean Zucker rats (LZR); lean Zucker rats plus exercise training (LZR+EXT); obese Zucker rat (OZR) and obese Zucker rat plus exercise training (OZR+EXT). EXT consisted of 10 weeks swimming sessions of 60 min, 5 days/week. At the end of the training protocol we evaluated heart rate (HR), systolic blood pressure (SBP), cardiac hypertrophy (CH) and function. The trained groups LZR+EXT and OZR+EXT showed a 12 percent lower resting HR when compared with theirs respective controls. In addition, our results showed that exercise training reduced the cardiac mass by 13 percent and improved the diastolic function by 43 percent in the obese trained group when compared with the obese untrained. In conclusion, aerobic exercise training reverts the cardiac injuries in obese Zucker rats.

Cardiovascular and autonomic modulation by the central nervous system after aerobic exercise training

The autonomic nervous system plays a key role in maintaining homeostasis under normal and pathological conditions. The sympathetic tone, particularly for the cardiovascular system, is generated by sympathetic discharges originating in specific areas of the brainstem. Aerobic exercise training promotes several cardiovascular adjustments that are influenced by the central areas involved in the output of the autonomic nervous system. In this review, we emphasize the studies that investigate aerobic exercise training protocols to identify the cardiovascular adaptations that may be the result of central nervous system plasticity due to chronic exercise. The focus of our study is on some groups of neurons involved in sympathetic regulation. They include the nucleus tractus solitarii, caudal ventrolateral medulla and the rostral ventrolateral medulla that maintain and regulate the cardiac and vascular autonomic tonus. We also discuss studies that demonstrate the involvement of supramedullary areas in exercise training modulation, with emphasis on the paraventricular nucleus of the hypothalamus, an important area of integration for autonomic and neuroendocrine responses. The results of these studies suggest that the beneficial effects of physical activity may be due, at least in part, to reductions in sympathetic nervous system activity. Conversely, with the recent association of physical inactivity with chronic disease, these data may also suggest that increases in sympathetic nervous system activity contribute to the increased incidence of cardiovascular diseases associated with a sedentary lifestyle.

Effects of aerobic exercise training of different intensities on circadian blood pressure / 中华物理医学与康复杂志

Objective To compare the effects of aero bi c exercise training of two different intensities on circadian blood pressure. Methods Twenty-eight sedentary patients with hyperte nsion were randomly allocated into 2 groups, and were treated with aerobic exerc ise training at 20% or 60% of the maximal intensity for 8 weeks, respectively. Not only were the relevant parameters of exercise capacity measured by use of m aximal bicycle ergometer tests, but also was the circadian blood pressure monito red pre-and post-therapy. Results Each paramet er of blood pressure decreased in both groups with similar circadian pattern. Conclusion The aerobic exercise training at 20% an d 60% of the maximal intensity have similar effects on circadian blood pressure.

Cardiorespiratory Responses of Pilots to Maximal Exercise Loading

BACKGROUND: To provide some fundamental physiological basis for the physical training of pilots to improve orthostatic intolerance, cardiorespiratory responses to the symptom-limited maximal exercise loading were studied in pilots and non-pilots, and the results were compared. METHOD: Cardiorespiratory reponses to the symptom-limited maximal exercise loading by Bruce protocol was studied in 11 pilots and 11 matched controls (non-pilots). RESULTS: Comparisons of various data at maximal exercise in the pilots with those in the controls revealed that RR, VE/M2, VE/VO2, VE/VCO2, VT/VC and VE/MVV as well as HR, VO2, O2 pulse and AT showed no significant difference. CONCLUSION: The fact that the aerobic power in the pilots is not superior to that in the controls seems to emphasisze the necessity of aerobic endurance training along with muscular strength training to improve orthostatic tolerance of pilots flying modern high-performance aircrafts.