Respostas autonômicas e hemodinâmicas ao exercício muscular inspiratório em indivíduos hipertensos não tratados

Abstract

Hypertension is a highly prevalent disease which can lead to cardiovascular diseases. On the other side, the regular practice of different physical exercises modalities can contribute to control or prevent it. Recently It’s been shown that the regular practice of inspiratory muscle exercise (IME) promote benefic chronic effects on the cardiovascular system in different populations including hypertensive people. However, there are little investigation about the acute and late cardiovascular effects following IME. Said that, this study had the objective, as a primary outcome, to evaluate the autonomic response and, as a secondary outcome, the hemodynamic effects, both following an IME session in not treated hypertensive individuals. To this end, fifteen sedentary men’s, with age between 30 and 57 years old, clinically diagnosed with hypertension, classified with low to moderate risk and that weren’t using drugs for blood pressure control, ware submitted randomly, at different days, to two exercise sections: IME at 40% of the volunteer’s maximal inspiratory pressure (MIP), and Sham (unload). The protocol consisted of 8 sets of 2 minutes with 1-minute interval between them. The cardiac autonomic modulation was evaluated by measuring the heart rate variability (HRV), calculated at time and frequency domains from the electrocardiographic signal. Mean arterial blood pressure (MAP), diastolic arterial blood pressure (DAP) and systolic arterial blood pressure (SBP) was the hemodynamic variables evaluated. The acute effects of IME were studied by comparing the measures pre-exercise and at 15, 30, 45 and 60 minutes after exercise. Additionally, the late effects of IME ware studied comparing the measures obtained by the electrocardiogram and of blood pressure ambulatorial monitorization over the next 20 hours after exercise sections. Two-way analysis of variance for repeated measures, followed by the Bonferroni post hoc was used for all comparisons, and was considered α = 5% as a significance level. Acutely, there was a reduction in heart rate (P < 0.001), and an increase in the mean duration of intervals between normal heart beats (P < 0.001) throughout the recovery period. And there was also an increase in the intervals’ standard deviation between normal heart beats (P = 0,002) from the 45 minutes post-exercise compared to the pre-exercise measures. In relation to the pressure variables, there was an increase in SBP (P < 0.001), DBP (P < 0.001) and MBP (P < 0,001) during the whole recovery period. There were no significant differences between the exercise sessions for any of the investigated variables. The analysis of late effects shown no changes in HRV measurements and pressure levels in response to both exercise sessions. Therefore, an IME session at 40% of the MIP or unloaded was able to promote acute improvement of the autonomic cardiac modulation. However, the two exercise sessions promoted sustained increase in blood pressure levels for up to one hour after its completion, not persisting in the subsequent 20 hours of follow-up in untreated hypertensive patients.