Impact of Modality and Intensity of Early Exercise Training on Ventricular Remodeling after Myocardial Infarction.

The objective of this study was to analyze the impact of different modalities and intensities of exercise training on cardiac remodeling started early after experimental myocardial infarction (MI). Male Wistar rats, weighing 200-250 g, were subjected to experimental MI. After 5 days, the animals were allocated into three experimental groups and observed for three months: S (sedentary control animals), C (animals subjected to continuous low-intensity training), and HIT (animals subjected to high-intensity interval training). Low-intensity exercise training was performed at a treadmill speed corresponding to 40% VO2 max, which was kept unchanged throughout the entire session (i.e., continuous low-intensity training). High-intensity interval training was performed in such a way that rats run during 3 min at 60% VO2 max, followed by 4-minute intervals at 85% VO2 max (i.e., high-intensity interval training). After the follow-up period, we studied hypertrophy and ventricular geometry, functional alterations in vivo and in vitro, oxidative stress, apoptosis, and cardiac energetic metabolism. Our data showed that both high-intensity interval and continuous low-intensity modalities improved cardiac energetic metabolism variables in comparison with sedentary infarcted animals. In addition, high-intensity interval training decreased cardiac oxidative stress, associated with improved diastolic function. On the other hand, the continuous low-intensity group showed impairment of cardiac function. Therefore, altogether, our data suggest that high-intensity interval training could be the best modality for early physical exercise after MI and should be better studied in this clinical scenario.

Influência do período de início do exercício físico na remodelação ventricular após o infarto do miocárdio / Influence of physical exercise period beginning on ventricular remodeling affer myocardial infarction

O objetivo do nosso estudo foi de avaliar a influência do período de início da atividade física sobre a remodelação após o infarto em ratos, por meio de análise de variáveis morfológicas, funcionais, bioquímicas, celulares e intersticiais cardíacas. Foram utilizados ratos wistar, machos, entre 200 – 250g foram submetidos ao infarto experimental. Após 48hs do procedimento, os animais sobreviventes foram alocados em três grupos aleatoriamente: grupo S (n=24): grupo de animais infartados; grupo P (n=24): grupo de animais infartados exercitados precocemente; grupo T(n=24): grupos de animais infartados exercitados tardiamente. Após 3 meses de acompanhamento foi realizado estudo morfológico e funcional pelos seguintes métodos: coração isolado, ecocardiograma, morfometria e histologia. O estudo bioquímico foi realizado pela área de miócitos, tamanho do infarto e porcentagem de colágeno do tecido cardíaco, por espectrofotometria foram avaliados estresse oxidativo e metabolismo energético. A análise estatística foi realizada pelo teste de ANOVA de uma via, O nível de significância adotado foi de 5%. Os resultados morfológicos avaliados pelo ecocardiograma mostram que os animais do grupo exercitado tardiamente apresentaram menor espessura da parede septal que o grupo P (S=1,69±0,28; P=1,81±0,34; T=1,46±0,22; p=0,041) e menores áreas diastólicas (S=105±12; P=96±23; T=87±11; p=0,010) e sistólicas (S=76±8; P=69±8; T=62±9; p=0,012) que o grupo S...

The aim of our study was to evaluate the influence of the period of early physical activity on remodeling after infarction in rats by analysis of morphological, functional, biochemical, cellular and interstitial heart. Wistar rats were used, males, between 200 - 250g were subjected to experimental infarction. After 48 hours of the procedure, the surviving animals were randomly allocated into three groups: group S (n = 24): group of infarcted animals, group P (n = 24): group of infarcted animals exercised early; Group T (n = 24) : groups of infarcted animals exercised later. After 3 months of followup was conducted morphological and functional study of the following methods: isolated heart, echocardiography, histology and morphometry. Biochemical analysis was performed by the area of myocytes, infarct size and percentage of collagen in the cardiac tissue were assessed by spectrophotometry oxidative stress and energy metabolism. Statistical analysis was performed by ANOVA one-way, the significance level was 5%. Morphological assessed by echocardiogram showed that the animals in the late exercised had lower septal wall thickness that the group P (S = 1.69 ± 0.28, P = 1.81 ± 0.34, T = 1 , 46 ± 0.22, p = 0.041) and lower diastolic areas (S = 105 ± 12, P = 96 ± 23, T = 87 ± 11, p = 0.010) and systolic (S = 76 ± 8, P = 69 ± 8, T = 62 ± 9, p = 0.012) than the group S...