title: Exercise as potential countermeasure for the effects of 70 days of bed rest on cognitive and sensorimotor performance.
abstract: BACKGROUND
  Spaceflight has been associated with changes in gait and balance; it is unclear whether it affects cognition. Head down tilt bed rest (HDBR) is a microgravity analog that mimics cephalad fluid shifts and body unloading. In consideration of astronaut's health and mission success, we investigated the effects of HDBR on cognition and sensorimotor function. Furthermore, we investigated if exercise mitigates any cognitive and sensorimotor sequelae of spaceflight.
  
  
  METHODS
  We conducted a 70-day six-degree HDBR study in 10 male subjects who were randomly assigned to a HDBR supine exercise or a HDBR control group. Cognitive measures (i.e., processing speed, manual dexterity, psychomotor speed, visual dependency, and 2D and 3D mental rotation) and sensorimotor performance (functional mobility (FMT) and balance performance) were collected at 12 and 8 days pre-HDBR, at 7, 50, and 70 days in HDBR, and at 8 and 12 days post-HDBR. Exercise comprised resistance training, and continuous and high-intensity interval aerobic exercise. We also repeatedly assessed an outside-of-bed rest control group to examine metric stability.
  
  
  RESULTS
  Small practice effects were observed in the control group for some tasks; these were taken into account when analyzing effects of HDBR. No significant effects of HDBR on cognition were observed, although visual dependency during HDBR remained stable in HDBR controls whereas it decreased in HDBR exercise subjects. Furthermore, HDBR was associated with loss of FMT and standing balance performance, which were almost fully recovered 12 days post-HDBR. Aerobic and resistance exercise partially mitigated the effects of HDBR on FMT and accelerated the recovery time course post-HDBR.
  
  
  CONCLUSIONS
  HDBR did not significantly affect cognitive performance but did adversely affect FMT and standing balance performance. Exercise had some protective effects on the deterioration and recovery of FMT.
authors.affiliation: School of Kinesiology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Koppelmans
authors.affiliation: NASA Johnson Space Center Houston, TX, USA ; Universities Space Research Association Houston, TX, USA.
authors.forename: Ajitkumar P
authors.initials: AP
authors.lastname: Mulavara
authors.affiliation: School of Kinesiology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Yuan
authors.affiliation: School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Kaitlin E
authors.initials: KE
authors.lastname: Cassady
authors.affiliation: School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Cooke
authors.affiliation: NASA Johnson Space Center Houston, TX, USA ; Department of Psychology, Azusa Pacific University Azusa, CA, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Wood
authors.affiliation: Department of Psychology, University of Michigan Ann Arbor, MI, USA ; Neuroscience Program, University of Michigan Ann Arbor, MI, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Reuter-Lorenz
authors.affiliation: Wyle Science, Technology and Engineering Group Houston, TX, USA.
authors.forename: Yiri E
authors.initials: YE
authors.lastname: De Dios
authors.affiliation: Wyle Science, Technology and Engineering Group Houston, TX, USA.
authors.forename: Vahagn
authors.initials: V
authors.lastname: Stepanyan
authors.affiliation: Bastion Technologies Houston, TX, USA.
authors.forename: Darcy L
authors.initials: DL
authors.lastname: Szecsy
authors.affiliation: Wyle Science, Technology and Engineering Group Houston, TX, USA.
authors.forename: Nichole E
authors.initials: NE
authors.lastname: Gadd
authors.affiliation: Wyle Science, Technology and Engineering Group Houston, TX, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Kofman
authors.affiliation: Universities Space Research Association Houston, TX, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Scott
authors.affiliation: Department of Health and Human Performance, University of Houston Houston, TX, USA.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Downs
authors.affiliation: NASA Johnson Space Center Houston, TX, USA.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Bloomberg
authors.affiliation: NASA Johnson Space Center Houston, TX, USA ; Universities Space Research Association Houston, TX, USA.
authors.forename: Lori
authors.initials: L
authors.lastname: Ploutz-Snyder
authors.affiliation: School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA ; Neuroscience Program, University of Michigan Ann Arbor, MI, USA ; Institute of Gerontology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Rachael D
authors.initials: RD
authors.lastname: Seidler
keywords: bed rest; cognition; exercise; longitudinal; microgravity; sensorimotor functioning; spaceflight analog