Respiratory muscle training improves hemodynamic function, chemoreflex response, heart rate variability and respiratory mechanics in rats with heart failure

Abstract

Background: The increase of respiratory muscles strength in patients with heart failure (HF) improves clinical outcomes related to the pathophysiological manifestations of HF. Also, in rats with HF, respiratory muscle training (RMT) is associated with improves in cardiopulmonary function, however, some physiological response remains unclear. Aims: To evaluate the RMT effects on hemodynamic function, chemoreflex response, heart rate variability and respiratory mechanics in HF rats. Methods: Wistar rats were allocated into four groups: sedentary sham ( n =8), trained sham ( n =8), sedentary HF ( n =8) and trained HF ( n =8). The rats were submitted to a RMT protocol performed a 30 min/day, 5 days/week, for 6 weeks, while the sedentary animals did not exercise. Groups were compared by a two-way ANOVA and Tukey´s post hoc test. Results: In rats with HF, RMT promoted the reduction of pulmonary congestion, the left ventricular end-diastolic pressure, as well as reduced right ventricular hypertrophy. Moreover, RMT produced reduction in pressure response during chemoreflex activation, sympathetic modulation and sympathetic-vagal balance, besides increase in parasympathetic modulation. After RMT, HF rats demonstrated reduction in the respiratory system resistance, tissue resistance, Newtonian resistance, respiratory system compliance and quasi-static compliance. Conclusions: These findings suggested that 6-weeks RMT in HF rats promoted beneficial adaptations on hemodynamic function, pressure response evoked by chemoreflex and respiratory mechanics in HF rats.