Hipotensão pós-exercício aeróbico e seus mecanismos hemodinâmicos e neurais em pré-hipertensos: influência da fase do dia e associação com a regulação endócrina circadiana

Abstract

At each time of day, one control (rest) and one exercise (cycle ergometer, 45 min, 50% of VO 2 peak) sessions were performed. Clinic BP, cardiac output (CO), systemic vascular resistance (SVR), stroke volume (SV), heart rate (HR), cardiac autonomic modulation, vasomotor modulation, baroreflex sensitivity, muscle blood flow, vasodilation and plasma concentrations of norepinephrine and epinephrine were measured before and after the intervention in each session. In addition, ambulatory BP was measured for 24 hours after the experimental sessions and the concentration of melatonin metabolite 6-sulfatoxymelatonin produced during the sleep before and after each session was assessed. Data were analyzed by 2 or 3-way ANOVA for repeated measures as well as by paired t test or Wilcoxon test, and the associations between variables were calculated by Pearson and Spearman correlations. P ≤ 0.05 was accepted as significant. Exercise produced a greater systolic BP reduction in the morning than the evening (-7 ± 3 -3 ± 4 mmHg, P<0.05), while the diastolic blood pressure decreased similarly in both times of day (-3±3 vs -3±3 mmHg, respectively, P<0.05). CO decreased and SVR tended to increased after exercise in the morning, while these variables did not change after exercise in the evening (-460 ± 771ml/min and +2.0 ± 3.8 mmHg.min/l; +148 633ml/min ± 2.8 and -1.4 ± mmHg.min/l , respectively). VS decreased similarly after 9 exercise in both times of day (-12 ± 15 vs -9 ± 10 ml, P<0.05), while the HR increased more in the evening (+7 ± 5 vs +10 ± 5 bpm, P<0.05). This occurred because exercise increased sympathovagal balance only in the evening (+1.5 ± 1.6, P<0.05), whereas vasomotor modulation decreased only after exercise performed in the morning (-0.5 ± 0.9 mmHg 2 , P<0.05). Spontaneous baroreflex sensitivity, measured by the average gain of positive and negative sequences (± SBR) decreased after the exercise in both times of day. The exercise did not affect arm blood flow and vasodilatory capacity, but increased leg vasodilation when exercise was performed in the evening (+116 ± 172 au, P<0.05). In regard to ambulatory measures, the exercise performed in the evening reduced asleep BP and BP measured 5-7hr post-exercise. The exercise did not have any effect in the norepinephrine, epinephrine and 6-sulphatoxymelatonin. Thus, there was not consistent correlation between the effect of exercise in hormone levels and in hemodynamic, autonomic and ambulatory responses. In conclusion, in prehypertensives, a single bout of aerobic exercise reduces post-exercise BP regardless if the exercise is performed in the morning or in the evening, however a greater hypotensive effect is observed in the morning for systolic BP. This greater systolic hypotensive effect is due to the decrease in CO in the morning, related to a decrease in SV and a lower increase in HR after the exercise performed in the morning, which is caused by a lower increase in sympathovagal balance and is accompanied by a smaller increase in active muscles vasodilatory capacit...

Chronic resistance training does not affect post-exercise blood pressure in normotensive older women: a randomized controlled trial

“…In our study, data collection occurred in the morning, while the other investigations were performed in the afternoon (Moraes et al 2012;Mota et al 2013). Brito (2013) observed that post-exercise hypotension was higher when the exercise was performed in the morning compared to the afternoon in prehypertensive adult men, which may explain the divergence between studies.…”

Influência da fase do dia nas adaptações cardiovasculares e no sono promovidas pelo treinamento aeróbico em hipertensos

“…Outro aspecto interessante neste contexto é que os estudos que investigaram a influência da fase do dia nas respostas agudas da PA após uma sessão de exercício aeróbico (BRITO, 2013;JONES et al, 2008;JONES, 2008) demonstraram maior redução da PA pósexercício (i.e. diferença pós-pré) quando o exercício foi realizado ao final do dia do que pela manhã.…”