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Laing, C; Green, DA; Mulder, E; Hinghofer-Szalkay, H; Blaber, AP; Rittweger, J; Goswami, N.
Effect of novel short-arm human centrifugation induced gravitational gradients upon cardiovascular responses, cerebral perfusion and g-tolerance.
J Physiol. 2020; Doi: 10.1113/JP273615 [OPEN ACCESS]
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Leading authors Med Uni Graz: Goswami Nandu
Co-authors Med Uni Graz: Hinghofer-Szalkay Helmut
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Abstract:: Aim of this study was to determine the effect of rotational axis position (RAP and thus g-gradient) during short-arm human centrifugation (SAHC) upon cardiovascular responses, cerebral perfusion and g-tolerance. In 10 male and 10 female participants, 10-min passive SAHC runs were performed with the RAP above (P1), or at the apex of the head (P2), or at heart-level (P3), with foot-level Gz at 1.0 g, 1.7 g and 2.4 g. We hypothesized that movement of the RAP from (the conventional position) above the head towards the heart may reduce central hypovolemia, limit cardiovascular responses, aid cerebral perfusion, and thus promote g-tolerance. Moving the RAP footward towards the heart decreased the cerebral tissue saturation index, calf circumference and heart rate responses to SAHC, thereby promoting g-tolerance. Our results also suggest that RAP, and thus g-gradient warrants further investigation as it may support use as a holistic spaceflight countermeasure. Artificial gravity (AG) through short-arm human centrifugation (SAHC) has been proposed as a holistic spaceflight countermeasure. Movement of the rotational axis position (RAP) from above the head towards the heart may reduce central hypovolemia, aid cerebral perfusion, and thus promote g-tolerance. This study determined the effect of RAP upon cardiovascular responses, peripheral blood displacement (i.e. central hypovolemia), cerebral perfusion and g-tolerance, and their inter-relationships. Twenty (10 male) healthy participants (26.2 ± 4.0 yr) underwent nine (following a familiarisation run) randomised 10-minute passive SAHC runs with RAP set above the head (P1), at the apex of the head (P2), or at heart-level (P3) with foot-level Gz at 1.0 g, 1.7 g and 2.4 g. Cerebral tissue saturation index (cTSI, cerebral perfusion surrogate), calf circumference (CC, central hypovolemia), heart rate (HR) and digital heart-level mean arterial blood pressure (MAP) were continuously recorded, in addition to incidence of pre-syncopal symptoms (PSS). ΔCC and ΔHR increases were attenuated from P1 to P3 (ΔCC: 5.46 ± 0.54 mm to 2.23 ± 0.42 mm; ΔHR: 50 ± 4 bpm to 8 ± 2 bpm, P < 0.05). In addition, ΔcTSI decrements were also attenuated (ΔcTSI: -2.85 ± 0.48% to -0.95 ± 0.34%, P < 0.05) and PSS incidence lower in P3 vs. P1 (P < 0.05). A positive linear relationship was observed between ΔCC and ΔHR with increasing +Gz, and a negative relationship between ΔCC and ΔcTSI, both independent of RAP. Our data suggests that movement of RAP towards the heart (reduced g-gradient), independent of foot-level Gz, leads to improved g-tolerance. Further investigations are required to assess effect of differential baroreceptor feedback (i.e. aortic - carotid g-gradient). This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Find related publications in this database (Keywords): artificial gravity; cardiovascular physiology; centrifuge; countermeasure; exercise physiology; short-arm human centrifuge; spaceflight