Contratilidade miocárdica de ratos infartados submetidos a treinamento de força

Abstract

Background/objectives: myocardial infarction (MI) frequently leads to cardiac remodeling and failure with impaired life quality, playing an important role in cardiovascular deaths. Although physical exercise is a well-recognized effective nonpharmacological therapy for cardiovascular diseases, the effects of strength training (ST) on the structural and functional aspects of cardiac remodeling need to be further documented. In this study we aimed to investigate the role of a linear block ST protocol in the rat model of MI. Methods and Results: After 6 weeks of MI induction, ST was instituted for the following 12 weeks. The ladder-based ST program was organized in three mesocycles of 4 weeks, with an increase in the load for each block according to the maximal carrying load test. After 12 weeks, the infarcted trained rats exhibited an increase in performance, associated with reduced cardiac hypertrophy and pulmonary congestion compared with the untrained group. Despite not changing MI size, the ST program partially prevented cardiac dilatation and ventricular function assessed by echocardiography and hemodynamics, and interstitial fibroses evaluated by histology. Also, the myocardial contraction from the trained infarcted rats partially preserved the contractility parameters in a steady state, in response to pause and to calcium concentrations, when compared to the untrained infarcted rats. Conclusions: trained group present increase in the capacity to carry mass, associated with attenuation of cardiac remodeling and pulmonary congestion with improving cardiac function that could be attributed, at least in part, to the partial preservation of myocardial contractility.