Original Research ARTICLE
Effects of Resistance Exercise and Nutritional Supplementation on Dynamic Cerebral Autoregulation in Head-Down Bed Rest
- 1INSERM U1048 Institut des Maladies Métaboliques et Cardiovasculaires, France
- 2Independent researcher, France
- 3Institut MITOVASC, France
- 4Independent researcher, France
- 5Independent researcher, France
- 6Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, United Kingdom
- 7Institute of Electronic Systems, Warsaw University of Technology, Poland
Head-down bed rest (HDBR) is commonly considered as ground-based analog to spaceflight and simulates the headward fluid shift and cardiovascular deconditioning associated with spaceflight. We investigated in healthy volunteers whether HDBR, with or without countermeasures, affect cerebral autoregulation (CA). Twelve men (at selection: 34±7 years; 176±7 cm; 70±7 kg) underwent three interventions of a 21-day HDBR: a control condition without countermeasure (CON), a condition with resistance vibration exercise (RVE) comprising of squats, single leg heel and bilateral heel raises and a condition using also RVE associated with nutritional supplementation (NeX). Cerebral blood flow velocity was assessed using transcranial Doppler ultrasonography. CA was evaluated by transfer function analysis and by the autoregulatory index (Mxa) in order to determine the relationship between mean cerebral blood flow velocity and mean arterial blood pressure. In RVE condition, coherence was increased after HDBR. In CON condition, Mxa index was significantly reduced after HDBR. In contrast, in RVE and NeX conditions, Mxa were increased after HBDR. Our results indicate that HDBR without countermeasures may improve dynamic CA, but this adaptation may be dampened with RVE. Furthermore, nutritional supplementation did not enhance or worsen the negative effects of RVE. These findings should be carefully considered and could not be applied in spaceflight. Indeed, the subjects spent their time in supine position during bed rest, unlike the astronauts who perform normal daily activities.
Keywords: Cerebral autogregulation, head-down bed rest, microgravity, Resistance vibration exercise, Nutritional supplementation
Received: 22 Mar 2019;
Accepted: 12 Aug 2019.
Copyright: © 2019 Kermorgant, Nasr, Custaud, Navasiolava, Arbeille, Guinet, Labrunée, Besnier, Arvanitis, Czosnyka, Senard and Pavy-Le Traon. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Mx. Marc Kermorgant, INSERM U1048 Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France, firstname.lastname@example.org