Efeito de uma sessão de exercício muscular inspiratório no sistema cardiovascular em idosos

Abstract

Introduction: The world is experiencing an increase of older population. Aging brings detrimental effects to the heart and lungs, which makes elders more susceptible to diseases. Interventions aiming to prevent or treat those diseases have been conducted in clinical practices, and among them is the inspiratory muscle training (IMT). Despite the known beneficial effects of IMT, the acute cardiovascular response to the inspiratory muscular exercise (IME) needs to be better understood. Objective: To evaluate the effects during and after a session of IME in elderly people. Method: Sixteen volunteers were evaluated, all men, elderly, sedentary, with no previous diagnosis of cardiovascular or pulmonary disease. The volunteers were randomly disposed into two experimental sessions: IME was composed of eight series of two minutes each, with one minute of rest between series, and with 40% of the maximum inspiratory pressure, and then another Sham session which was conducted the same way, but without weights. The evaluated indicators were: blood pressure (BP) (Finometer Pro); stroke volume (SV), cardiac output (CO), total peripheral vascular resistance (TPVR - Finometer Pro); forearm blood flow (FBF - Hokanson Plestimograph) and heart rate (HR - ECG). The forearm vascular resistance (FVR) was calculated through the following formula: mean arterial pressure divided by the forearm blood flow, and reported in units. The spontaneous baroreflex function was evaluated through the sequential method (time domain) using the software CardioSeries v2.4. All variables were measured during the sessions, and during 60 minutes imediatly after the sessions. BP was recorded for 24 hours after the sessions. For the responses during and after sessions (recovery of 60 minutes) as well as for the 24-hour temporal behavior, we used Anova of two factors with post hoc of Bonferroni when necessary. A Student's t-test over the paired sample was conducted for the volunteers' resting hemodynamic characteristics, before the experimental sessions (IME and Sham), for the Borg values after the exercises (IME and Sham), as well as for the 24 hours response. We adopted as effect size, Cohen’s d. Results: During both experimental sessions, we found HR elevation, reduction of SV, a non-sustained rise in BP, and the non-modification of CO, FVR and TPVR values. In the 60 minutes of recovery, for both sessions, the reduction of the HR, non-modification of SV values, reduction of FBF, rise in BP, FVR e TPVR were noticed. In the IME session the non-modification of the CO levels were observed, but in the Sham session they were reduced. In the 60 minutes of recovery the baroreflex function’s indices remained unaltered. The mean values for the systolic and diastolic blood pressure of the 24 hours after both experimental sessions were very similar. Conclusion: Elderly men without previously diagnosed cardiovascular diseases will display raised HR, raised non-sustained BP, reduced SV, and unaltered levels of CO and TPVR during IME sessions. The study also allow us to conclude that elderly men, during the first 60 minutes after an IME session, display reduced HR, raised BP, unaltered levels of SV and CO, elevated TPVR, reduced FBF, raised FVR and unaltered indices of barorrefex function. Finally, through this study, we are able to learn that there is no difference in the 24 hour BP recovery between the sessions where IME and Sham were conducted.