Time of day influence on cardiovascular and sleep quality adaptations promoted by aerobic training in hypertensive subjects

Abstract

Aerobic training is recommended to hypertensive subjects due to decreasing blood pressure (BP) after single and chronic intervention. Although aerobic exercise promotes BP decrease any time of day, the circadian behavior of BP suggests that to perform exercise in different times of day can promote different responses. An acute aerobic exercise bout performed in the evening promotes a greater BP decrease than morning (post - pre values). As there is a strong relation between acute and chronic BP response to aerobic exercise, BP decrease can be greater after aerobic training performed in the evening. Moreover, a lot of factors, as sleep quality and hemodynamic, autonomic and neuroendocrine alterations are related to hypertension, all of them improved by aerobic training. However, the time of day effect that training is performed was still not investigated. Thus, the aim of this study will be to assess and to compare the effect of aerobic training performed in the morning (M) and evening (E) on BP, its hemodynamic, autonomic and endocrine mechanisms, as well as on sleep quality in medicated hypertensive men. For this, 64 medicated hypertensive men (30 to 60 years) will be allocated in 4 groups randomly: morning training (MT), evening training (ET), morning control (MC) and evening control (EC). T groups will pedaling on bicycle progressing from 30 to 45 min and from heart rate of anaerobic threshold to heart rate 10% less than respiratory compensation point. C groups will perform stretching training for 30 min. All of the groups will training for 10 weeks 3 times/week. Before and after interventions, all individuals will perform 2 ergospirometric tests, one in the M and one E, sleep quality will be assessed during these visits. Moreover, individuals will perform an experimental session which will be assessed following variables in the M and E: i) clinic and 24h BP; ii) cardiac output, heart rate, stroke volume and systemic vascular resistance; iii) rest blood flow and vasodilatory response to reactive hyperemia; iv) cardiac and vasomotor autonomic modulation and baroreflex sensibility; v) angiotensina II, angiotensina 1-7, and vasopressin plasma levels and urinary melatonin. ANOVA 3 way will be employed with a set of Pd0.05. (AU)