Effect of the time of day at which aerobic training is performed on vascular function in treated elderly hypertensives

• Grant number: 22/12605-3
• Support Opportunities: Regular Research Grants
• Duration: February 01, 2023 - January 31, 2025
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Cláudia Lúcia de Moraes Forjaz
• Grantee: Cláudia Lúcia de Moraes Forjaz
• Host Institution: Escola de Educação Física e Esporte (EEFE). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: John Robert Halliwill ; Kátia de Angelis Lobo D Avila ; Leandro Campos de Brito

Abstract

Hypertension is highly prevalent in elderly individuals. The blood pressure (BP) increase observed with aging is attributed to many physiological alterations. Among them, the vascular changes, expressed by the increase in arterial wall thickness and stiffness in combination with the decrease in vascular conductance and endothelial function are highlighted for this study. These changes may lead to the increase in systemic vascular resistance (SVR) that is the main determinant of BP increase in hypertension. Aerobic training (AT), recommended for hypertension treatment, decreases BP partially by acting on the overmentioned vascular mechanisms. Additionally, in previous studies supported by FAPESP, we reported that AT preformed in the morning induces greater BP-lowering than AT executed in the evening, which shows a possible circadian influence on the vascular effects of AT, which needs to be further investigated to allow a more comprehensive understanding of this phenomenon aiming its clinical application. Therefore, this study aims to compare the effects of AT performed at different times of day (morning vs. evening) on vascular mechanisms related to BP control in elderly hypertensives. For that, 60 elderly hypertensives from both genders and taking regular antihypertensive drugs will be randomly divided in 3 groups: morning AT (7-10 a.m.); evening AT (5-8 p.m.) and control (half in each time of day). Before and after 10 weeks of intervention, the following outcomes will be assessed: BP (auscultatory), cardiac output and SVR (CO2 reinhalation), carotid artery stiffness (² index), vascular conductance and endothelial function (ultrasonography - brachial artery), and NO bioavailability (nitrate/nitrite ratio). During the intervention period, AT groups will exercise on cycle ergometers, 3 times per week, for 30-45 min at moderate intensity; while the control group will execute 30 min of stretching exercises. Data will be analyzed by mixed 2-way ANOVAs, considering p lower or equal to 0.05 as significant. (AU)