Assessing the effects of artificial gravity in an analog of long-duration spaceflight: The protocol and implementation of the AGBRESA bed rest study

Abstract

A comprehensive strategy is required to mitigate risks to astronauts' health, well-being, and performance. This strategy includes developing countermeasures to prevent or reduce adverse responses to the stressors astronauts encounter during spaceflight, such as weightlessness. Because artificial gravity (AG) by centrifugation simultaneously affects all physiological systems, AG could mitigate the effects of weightlessness in multiple systems. In 2019, NASA and the German Aerospace Center conducted a 60-days Artificial Gravity Bed Rest Study with the European Space Agency (AGBRESA). The objectives of this study were to 1) determine if 30 min of AG daily is protective during head down bed rest, and 2) compare the protective effects of a single daily bout (30 min) of AG versus multiple daily bouts (6 × 5 min) of AG (1 Gz at the center of mass) on physiological functions that are affected by weightlessness and by head-down tilt bed rest. The AGBRESA study involved a comprehensive suite of standard and innovative technologies to characterize changes in a broad spectrum of physiological systems. The current article is intended to provide a detailed overview of the methods used during AGBRESA.

Keywords: analogs; artificial gravity; bed rest; countermeasures; weightlessness.

FIGURE 1

Schematic representation of the AGBRESA study design. FRED is a functional re-adaptive exercise device (Debuse et al., 2013) used during the recovery phase. Ctrl: control group, no centrifugation; cAG: continuous centrifugation for 30 min; iAG intermittent centrifugation for 6 × 5 min.

FIGURE 2

Number of candidates during the various steps of the selection process.

FIGURE 3

Details of the side pillow used to maintain the subjects’ head in the 6° HDT position when lying on their side.

FIGURE 4

An operator is prepping a subject for a run on the DLR SAHC-1centrifuge. The subject is in HDT prior to centrifuge rotation.

FIGURE 5

Daily group averages ± SD of the measured general health measurements for the three subject groups (8 subjects per group): heart rate, mean blood pressure, systolic blood pressure (BP), diastolic BP, temperature, 24-h urine volume, and body weight.

FIGURE 6

Frequency of adverse effects during the HDT phase for each subject group.

FIGURE 7

Average acceptability of the AG countermeasure measured in weekly intervals for the cAG and iAG subject groups (8 subjects per group). Mean ± SD.

FIGURE 8

(A). Mean ± SD of the composite Readaptation Symptom Severity (RSS) scores in the three subject groups on R+0 and R+3. (B). RSS sub-scores in the three subject groups for neurovestibular and other symptoms on R+0.