title: Effects of an artificial gravity countermeasure on orthostatic tolerance, blood volumes and aerobic power after short-term bed rest (BR-AG1).
abstract: Exposure to artificial gravity (AG) in a short-arm centrifuge has potential benefits for maintaining human performance during long-term space missions. Eleven subjects were investigated during three campaigns of 5 days head-down bed rest: 1) bed rest without countermeasures (control), 2) bed rest and 30 min of AG (AG1) daily, and 3) bed rest and six periods of 5 min AG (AG2) daily. During centrifugation, the supine subjects were exposed to AG in the head-to-feet direction with 1 G at the center of mass. Subjects participated in the three campaigns in random order. The cardiovascular effects of bed rest and countermeasures were determined from changes in tolerance to a head-up tilt test with superimposed lower body negative pressure (HUT), from changes in plasma volume (PV) and from changes in maximum aerobic power (V̇o2 peak) during upright work on a cycle ergometer. Complete data sets were obtained in eight subjects. After bed rest, HUT tolerance times were 36, 64, and 78% of pre-bed rest baseline during control, AG1 and AG2, respectively, with a significant difference between AG2 and control. PV and V̇o2 peak decreased to 85 and 95% of pre-bed rest baseline, respectively, with no differences between the treatments. It was concluded that the AG2 countermeasure should be further investigated during future long-term bed rest studies, especially as it was better tolerated than AG1. The superior effect of AG2 on orthostatic tolerance could not be related to concomitant changes in PV or aerobic power.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; dag.linnarsson@ki.se.
authors.forename: Dag
authors.initials: D
authors.lastname: Linnarsson
authors.affiliation: Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada;
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hughson
authors.affiliation: Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada;
authors.forename: Katelyn S
authors.initials: KS
authors.lastname: Fraser
authors.affiliation: International Space University, Illkirch-Graffenstaden, France;
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Lars L
authors.initials: LL
authors.lastname: Karlsson
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany;
authors.forename: Edwin
authors.initials: E
authors.lastname: Mulder
authors.affiliation: Neuroscience Research Laboratories, National Aeronautics and Space Administration/Johnson Space Center, Houston, Texas; Center for Neuromotor and Biomechanics Research, University of Houston, Houston, Texas;
authors.forename: William H
authors.initials: WH
authors.lastname: Paloski
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany; Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, United Kingdom; and.
authors.forename: Jörn
authors.initials: J
authors.lastname: Rittweger
authors.affiliation: Department of Otolaryngology, Antwerp University Research Center for Equilibrium and Aerospace, Antwerp, Belgium.
authors.forename: Floris L
authors.initials: FL
authors.lastname: Wuyts
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany;
authors.forename: Jochen
authors.initials: J
authors.lastname: Zange
mesh_terms: D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D001810:Blood Volume / Q000502:physiology*; D018592:Cross-Over Studies; D018470:Gravity, Altered; D006801:Humans; D008297:Male; D054971:Orthostatic Intolerance / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D016683:Supine Position; D016896:Treatment Outcome
keywords: head-down tilt; head-up tilt; intermittent; lower body negative pressure; short-arm centrifuge