Long-Duration Head-Down Bed Rest: Project Overview, Vital Signs, and Fluid Balance

Abstract

The following reports describe multi-disciplinary results from the standard measurements by which the responses to bed rest will be assessed and by which countermeasures will be evaluated. The data presented in this overview are meant to serve as a context in which to view the data presented in the discipline specific manuscripts. The dietary support and behavioral health papers provide additional information regarding those aspects of implementing bed rest studies successfully.

Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes

“…They were monitored to ensure round-the-clock compliance. Details have been reported elsewhere (34)(35)(36). In this study, 12 subjects (8 male subjects and 4 female subjects) with an age range of 25-49 y and an average age of 32 ± 8 y were enrolled.…”

“…Demographic information for each subject is presented in Table S3. Details of participant recruitment and exclusion criteria are given elsewhere (35). Subjects began the ∼54-d study at different times throughout a 6-mo period.…”

Structural Brain Changes following Long-Term 6° Head-Down Tilt Bed Rest as an Analog for Spaceflight

“…A traditional ground-based analog used by NASA and other international space agencies to study physiologic changes associated with long-term spaceflight has been to place healthy subjects in 6°head-down tilt bed rest for varying periods. 2,3 Anecdotally, Russian scientists first devised the head-down-tilt protocol in the early 1970s on the basis of reports by Russian cosmonauts who had the sensation of slipping off the foot of the bed on return to Earth after long-duration missions. 3 The foot of the bed was raised until it felt horizontal to help the cosmonauts sleep.…”

“…2 Informed consent was obtained, and the study was approved by the appropriate institutional review boards. Subject recruitment included radio, television, and newspaper announcements and a Web site (www.bedreststudy.com).…”

“…2 Before bed rest, subjects were admitted to the NASA Flight Analogs Facility and underwent a NASA-modified Air Force Class III physical examination and psychological assessment. Subjects then remained in the unit for 11-14 days before the start of bed rest for pre-bed rest data collection performed by other investigators and were free to ambulate normally.…”