Acute cardiovascular adaptation to 10 consecutive episodes of head-up tilt

Berry, N, Rickards, C and Newman, D 2006, 'Acute cardiovascular adaptation to 10 consecutive episodes of head-up tilt', Aviation, Space and Environmental Medicine, vol. 77, no. 5, pp. 494-499.


Document type: Journal Article
Collection: Journal Articles

Title Acute cardiovascular adaptation to 10 consecutive episodes of head-up tilt
Author(s) Berry, N
Rickards, C
Newman, D
Year 2006
Journal name Aviation, Space and Environmental Medicine
Volume number 77
Issue number 5
Start page 494
End page 499
Total pages 6
Publisher Aerospace Medical Association
Abstract BACKGROUND - The cardiovascular system is highly adaptable to sustained +Gz acceleration. Little is known as to whether the cardiovascular system can adapt to acute, repetitive +Gz exposures. This study tested the hypothesis that the cardiovascular system would adapt to repeated orthostatic challenges in a single session. METHODS - Over a 70-min period, 14 subjects were exposed to 10 +75º head-up tilts (HUT). Each tilt involved a 5-min supine period followed by a 2-min HUT. Heart rate (HR), systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), total peripheral resistance (TPR), stroke volume (SV), and cardiac output (CO) were determined non-invasively. Cardiovascular responses to HUT10 for the final 30 s of the supine period and the first 30 s of the tilt period were compared with those of HUT1. Integrated cardiac baroreflex sensitivity (BRS) was assessed using the Valsalva maneuver. RESULTS - MAP and DBP increased in both supine (MAP p = 0.009, DBP p = 0.002) and tilt periods (MAP p = 0.003,DBP p = 0.009) for HUT10 compared with HUT1. TPR increased during the tilt period only (p = 0.001) during HUT10 compared with HUT1. CO and SV were decreased during the supine period at HUT10 relative to HUT1; however, there were no differences in the tilt period at HUT10 for either CO or SV. There was no change in the response of BRS, HR, or SBP from HUT1 to HUT10. CONCULUSIONS - This study indicates that 10 repetitive HUTs can elicit changes in the cardiovascular responses to orthostasis, reflected by an increased vascular resistance.
Subject Human Movement and Sports Science not elsewhere classified
Keyword(s) Public
Environmental & Occupational Health
Medicine
General & Internal
Sport Sciences
ISSN 0095-6562
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