Efeito do exercício muscular inspiratório sobre as variáveis hemodinâmicas de jovens saudáveis

Abstract

Introduction: Inspiratory muscle training that consists of inspiratory muscle exercise (IME) sessions is a potential and pharmacological strategy used to increase inspiratory muscle strength. However, divergence of the scientific literature about the time and workload used in EMI sessions, as well as the hemodynamic response due to the various EMI intensities need to be better clarified. Thus, it is essential to develop controlled and randomized studies that explore and compare the hemodynamic response at different EMI session intensities. Objective: To evaluate the hemodynamic response during and after sessions of different EMI intensities in healthy young adults. Methods: Fifteen men (25 ± 1 years old, BMI 23.5 ± 0.8 kg / m2), who underwent four EMI sessions: Sham (no additional load), EMI 30%, EMI 40% and EMI 60% of maximal inspiratory pressure (MIP). The Sham session, EMI 30% and EMI 40% were performed with 8 sets of 2 minutes per 1 minute interval. The EMI 60% MIP session was performed with 4 sets of 2 minutes per 1 minute interval. In all sessions the respiratory rate was maintained between 12 and 15 breaths/min. MIP was evaluated by manovacuometry (MVD300). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), total peripheral resistance (TPR) and heart rate (HR) were evaluated by the noninvasive technique of infrared digital photoplethysmography (FinometerPRo). The muscular blood flow of the forearm (FSM) was evaluated by venous occlusion plethysmography (Hokanson) technique. Forearm vascular resistance (AVR) was calculated by dividing the MAP by the FSM. All variables were measured simultaneously for 10 minutes at rest, during EMI and in the recovery period (15, 30, 45 and 60 minutes) after the EMI sessions. HR and blood pressure were monitored for 24 hours after Sham and EMI 40% sessions. One-way ANOVA was used for repeated measures for analysis of hemodynamic variables during EMI, ANOVA 2 factors for repeated measurements for analysis of hemodynamic variables at rest, recovery (60 minutes) and at 24 hours, followed by post hoc Bonferroni. The t test was used to compare deltas of the hemodynamic variables during the Sham vs. EMI 40% and EMI 30% vs EMI 60%. The D Cohen was used to compare the size of the delta average effect. To analyze the size of the effect of hemodynamic variables during EMI and 60 minutes recovery (Sham vs EMI 40% and EMI 30% vs EMI 60%) the Partial Eta Esquared was adopted. For significant difference p <0.05 was considered. Results: During the experimental sessions, we verified HR increase during the Sham, EMI 30%, EMI 40% and EMI 60% sessions. Only in the Sham protocol did we observe the reduction of VS. Only in the EMI 60% did we observe increased SBP, DBP, MAP, DC and AVR. In the first 60 minutes of recovery after EMI, we observed a reduction in HR, FSH and DC after all EMI protocols were performed. In addition, we observed increased RPT and AVR, which probably resulted in increased pressure. At 24-hour recovery, we did not find differences in pressure and HR behavior between Sham and EMI 40% sessions. Conclusion: Only the EMI 60% protocol provided considerable changes in hemodynamic response. In the first 60 minutes of recovery after EMI all the different protocols caused bradycardia to the point of reducing DC. Although blood pressure levels increased for up to one hour after EMI, this effect did not persist in the subsequent 24 hours. Finally, for the 24-hour response, we found pressure levels within the normal range, nocturnal BP decrease, demonstrating the appropriate physiological behavior.