Respostas fisiológicas agudas de uma sessão de exercício intervalado: esteira vs. resistência elástica

Abstract

Introduction: A novel proposal of High-Intensity Interval Training (HIIT) with elastic resistance (EL-HIIT) has been under investigation. EL-HIIT is easy to apply and accessible; however, its efficacy and safety in terms of acute responses still need to be studied. Objective: To compare the cardiopulmonary and blood pressure responses after a single session of two types of high-intensity interval training (EL-HIIT vs. HIIT on the treadmill) in healthy young individuals. Methods: Twenty-two participants underwent two incremental tests, the Cardiopulmonary Exercise Test (CPET) and the Elastic Cardiopulmonary Exercise Test (ECPET), with a one-week interval between them. Subsequently, they performed a session of HIIT on the treadmill (10 x 1:1 min at 85-90% V̇ O2max from CPET), and after a one-week interval, a session of EL-HIIT (10 x 1:1 min at 85-90% V̇ O2max). The Student's t-test was used to compare peak and mean values of the HIIT and EL-HIIT sessions. ANOVA and MixedEffects Model of Repeated Measures (Bonferroni/Tukey post-hoc) were used to compare HIIT, EL-HIIT, and control (for heart rate variability - HRV and blood pressure - BP). Cohen's d effect size was used to compare the sessions. To assess inter and intra-individual BP, MDD (minimum detectable difference), ICC (intra-class correlation coefficient), CV (coefficient of variation), SEM (standard error of measurement), and ET (typical error) were used. Results: In the EL-HIIT session, heart rate (HR), ventilation (V̇ E), oxygen consumption (V̇ O2), carbon dioxide production (V̇ CO2), and rate of perception exertion (RPE) were higher than in the HIIT session (P < 0.05). Comparing HIIT and EL-HIIT, no differences were found when analyzing each interval during the session. In recovery, there was a decrease in systolic blood pressure (SBP) for both EL-HIIT and HIIT, but of greater magnitude in EL-HIIT, as calculated by MDD, at 50, 70, and 80 minutes post-exertion compared to control (P < 0.05). The intra-individual analyses of systolic and diastolic blood pressure showed ICC of 0.92 and 0.88, CV of 6.0 and 9.5%, and MDD of 4.1 and 4.3, respectively. EL-HIIT presented higher sympathetic autonomic variables (stress index, SNS index) compared to HIIT/control and lower parasympathetic autonomic variables (RMSSD, pNN50, PNS index) compared to HIIT/control after exertion (P < 0.05). Conclusion: A single session of EL-HIIT promoted a greater magnitude of post-exercise ypotension compared to HIIT. EL-HIIT presented higher autonomic stress in recovery compared to HIIT without changes in nitrite/nitrate concentrations.