| Grant number: | 13/04997-0 |
| Support Opportunities: | Regular Research Grants |
| Start date: | August 01, 2013 |
| End date: | July 31, 2015 |
| 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 |
| City of the host institution: | São Paulo |
| Associated researchers: | Decio Mion Junior ; Taís Tinucci |
Abstract
Post-exercise heart rate recovery (HRR) provides the assessment of the cardiac autonomic responsiveness to a physiological stress. Studies have shown that reduced HRR values are associated with greater mortality rates. Hypertension is a high-prevalent disease with poor cardiovascular prognostic. Studies have shown a reduced HRR in hypertensive subjects compared with normotensives. This autonomic dysfunction may reflect a lower efficiency of the cardiovascular control mechanisms, such as central command, mechanoreflex, metaboreflex and thermoregulation. Nevertheless, the role and the impairment of these mechanisms on the HRR reduction in this population are not clear. The aim of this study, therefore, is to investigate the role of the cardiovascular control mechanisms on HRR of hypertensive. 25 hypertensive and 25 normotensive subjects will undergo 5 experimental sessions conducted in a random order. During the sessions, measurements will be done at rest, exercise (cycle ergometer, 30 min, 70% of maximal workload) and recovery. In each sessions, the post-exercise recovery will be conducted in different ways: a) passive recovery - absence of movement; b) active recovery - maintaining the movement at a lower intensity; c) assisted recovery - maintaining of the movement at a lower intensity by an external force; d) passive recovery with circulatory occlusion and e) passive recovery with cooling ventilation. In all the sessions, the electrocardiogram, respiratory signal and photoplethysmographic blood pressure will be continuously recorded. Moreover, blood lactate concentration will be measured in specific moments. Each two sessions results will be compared for assessing the role of the cardiovascular control mechanism on HRR: central command (b vs. c), mechanoreflex (a vs. c), metaboreflex (a vs. d) and thermoregulation (a vc. e.). Data will be analyzed by a 2-way ANOVA for repeated measures, using group and the session as the main within factors. (AU)
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