Cardioprotection afforded by exercise training prior to myocardial infarction is associated with autonomic function improvement.

BACKGROUND: It has been suggested that exercise training (ET) protects against the pathological remodeling and ventricular dysfunction induced by myocardial infarction (MI). However, it remains unclear whether the positive adjustments on baroreflex and cardiac autonomic modulations promoted by ET may afford a cardioprotective mechanism. The aim of this study was to evaluate the effects of aerobic ET, prior to MI, on cardiac remodeling and function, as well as on baroreflex sensitivity and autonomic modulation in rats. METHODS: Male Wistar rats were divided into 4 groups: sedentary rats submitted to Sham surgery (C); trained rats submitted to Sham surgery (TC); sedentary rats submitted to MI (I), trained rats submitted to MI (TI). Sham and MI were performed after ET period. After surgeries, echocardiographic, hemodynamic and autonomic (baroreflex sensitivity, cardiovascular autonomic modulation) evaluations were conducted. RESULTS: Prior ET prevented an additional decline in exercise capacity in TI group in comparison with I. MI area was not modified by previous ET. ET was able to increase the survival and prevent additional left ventricle dysfunction in TI rats. Although changes in hemodynamic evaluations were not observed, ET prevented the decrease of baroreflex sensitivity, and autonomic dysfunction in TI animals when compared with I animals. Importantly, cardiac improvement was associated with the prevention of cardiac autonomic impairment in studied groups. CONCLUSIONS: Prior ET was effective in changing aerobic capacity, left ventricular morphology and function in rats undergoing MI. Furthermore, these cardioprotective effects were associated with attenuated cardiac autonomic dysfunction observed in trained rats. Although these cause-effect relationships can only be inferred, rather than confirmed, our study suggests that positive adaptations of autonomic function by ET can play a vital role in preventing changes associated with cardiovascular disease, particularly in relation to MI.

Resistance training after myocardial infarction in rats: its role on cardiac and autonomic function.

BACKGROUND: Although resistance exercise training is part of cardiovascular rehabilitation programs, little is known about its role on the cardiac and autonomic function after myocardial infarction. OBJECTIVE: To evaluate the effects of resistance exercise training, started early after myocardial infarction, on cardiac function, hemodynamic profile, and autonomic modulation in rats. METHODS: Male Wistar rats were divided into four groups: sedentary control, trained control, sedentary infarcted and trained infarcted rats. Each group with n = 9 rats. The animals underwent maximum load test and echocardiography at the beginning and at the end of the resistance exercise training (in an adapted ladder, 40% to 60% of the maximum load test, 3 months, 5 days/week). At the end, hemodynamic, baroreflex sensitivity and autonomic modulation assessments were made. RESULTS: The maximum load test increased in groups trained control (+32%) and trained infarcted (+46%) in relation to groups sedentary control and sedentary infarcted. Although no change occurred regarding the myocardial infarction size and systolic function, the E/A ratio (-23%), myocardial performance index (-39%) and systolic blood pressure (+6%) improved with resistance exercise training in group trained infarcted. Concomitantly, the training provided additional benefits in the high frequency bands of the pulse interval (+45%), as well as in the low frequency band of systolic blood pressure (-46%) in rats from group trained infarcted in relation to group sedentary infarcted. CONCLUSION: Resistance exercise training alone may be an important and safe tool in the management of patients after myocardial infarction, considering that it does not lead to significant changes in the ventricular function, reduces the global cardiac stress, and significantly improves the vascular and cardiac autonomic modulation in infarcted rats.

Resistance Training After Myocardial Infarction in Rats: Its Role on Cardiac and Autonomic Function / Treinamento Resistido Após Infarto do Miocárdio em Ratos: Papel na Função Cardíaca e Autonômica

Background: Although resistance exercise training is part of cardiovascular rehabilitation programs, little is known about its role on the cardiac and autonomic function after myocardial infarction. Objective: To evaluate the effects of resistance exercise training, started early after myocardial infarction, on cardiac function, hemodynamic profile, and autonomic modulation in rats. Methods: Male Wistar rats were divided into four groups: sedentary control, trained control, sedentary infarcted and trained infarcted rats. Each group with n = 9 rats. The animals underwent maximum load test and echocardiography at the beginning and at the end of the resistance exercise training (in an adapted ladder, 40% to 60% of the maximum load test, 3 months, 5 days/week). At the end, hemodynamic, baroreflex sensitivity and autonomic modulation assessments were made. Results: The maximum load test increased in groups trained control (+32%) and trained infarcted (+46%) in relation to groups sedentary control and sedentary infarcted. Although no change occurred regarding the myocardial infarction size and systolic function, the E/A ratio (-23%), myocardial performance index (-39%) and systolic blood pressure (+6%) improved with resistance exercise training in group trained infarcted. Concomitantly, the training provided additional benefits in the high frequency bands of the pulse interval (+45%), as well as in the low frequency band of systolic blood pressure (-46%) in rats from group trained infarcted in relation to group sedentary infarcted. Conclusion: Resistance exercise training alone may be an important and safe tool in the management of patients after myocardial infarction, considering that it does not lead to significant changes in the ventricular function, reduces the global cardiac stress, and significantly improves the vascular and cardiac autonomic modulation in infarcted rats. .

Fundamento: Embora o treinamento físico resistido esteja inserido nos programas de reabilitação cardiovascular, pouco se sabe sobre seu papel isolado na função cardíaca e autonômica após o infarto do miocárdio. Objetivo: Avaliar os efeitos do treinamento físico resistido iniciado precocemente após o infarto do miocárdio na função cardíaca, no perfil hemodinâmico e na modulação autonômica de ratos. Métodos: Ratos Wistar machos foram divididos em Grupos Controle Sedentário, Controle Treinado, Infartado Sedentário e Infartado Treinado. Cada grupo foi composto por 9 ratos. Os animais realizaram o teste de carga máxima e a ecocardiografia ao início e ao final do treinamento físico resistido (em escada adaptada, 40 a 60% do teste de carga máxima, 3 meses, 5 dias/semana). Ao final, foram realizadas avaliações hemodinâmicas, de sensibilidade barorreflexa e da modulação autonômica. Resultados: O teste de carga máxima aumentou nos Grupos Controle Treinado (+32%) e Infartado Treinado (+46%) em relação aos Grupos Controle Sedentário e Infartado Sedentário. Embora a área de infarto do miocárdio e a função sistólica não tenham sido alteradas, a relação E/A (-23%), o índice de desempenho miocárdico (-39%) e a pressão arterial sistólica (+6%) foram melhorados pelo treinamento físico resistido no Grupo Infartado Treinado. Paralelamente, o treinamento induziu os grupos a benefícios adicionais nas bandas de alta frequência do intervalo de pulso (+45%), bem como a banda de baixa frequência da pressão arterial sistólica (-46%) nos ratos do Grupo Infartado Treinado em relação aos do Infartado Sedentário. Conclusão: O treinamento físico resistido dinâmico ...