APPROACH:
The torque-velocity relationships of the knee extensors and calf plantar flexors were determined using a Cybex dynamometer. Knee and ankle flexors, as well as trunk extensors and flexors, were also tested to satisfy the requirements of the standard measures for the Bed Rest Project. The Cybex isokinetic dynamometer is an exercise device used clinically by physicians and physical therapists to rehabilitate and test athletes and persons with injury. This isokinetic device controls the speed at which a person moves their limb and measures the torque developed when the person tries to move faster than the machine will allow. This type of exercise is inherently safer than typical weight lifting exercises. The subjects became accustomed to the function of the test apparatus one week prior to the first test session.

The test began with a 5 minute warm-up on a cycle ergometer, pedaling at a comfortable pace of 25-50 Watts. Subjects then performed tests of the knee joint, ankle joint, and back. Each test was preceded by a joint specific warm-up and practice of each movement before data collection began. During each test session, the subjects performed five trials at each test speed. Angle-specific torque was determined for all measurements of knee and ankle extension torque. Subjects were encouraged to make maximal efforts throughout the range of motion. The best effort at each speed was used for data analyses.

An additional measure of power was included for the Artificial Gravity (AG) Pilot Study. Single joint measures of explosive power can be determined from the force-time curve generated during isometric force tests.

RESULTS:
This experiment has concluded. Summarized results for this test aren't available.

The overall objective of this study was to identify suitable combinations of automated text processing techniques, which investigators call “Non-Intrusive Psycho-Social State Assessors” or NIPSSAs and data streams for assessing psychosocial states of interest to NASA and to validate their overall hypothesis that NIPSSA measures could replace survey data for assessing selected psychosocial states. Astronauts’ journals, diaries, and blogs are a rich source of material about their experiences and attitudes toward those experiences, and interpersonal communications are, after all, one of the best methods humans have of assessing changes in attitudes and states. The investigators reasoned that if they could automate assessments of such data streams, many of which are already being captured and, to some extent, monitored during space missions, they would greatly expand the set of data which NASA team dynamics researchers have available.

APPROACH:
The first year of the project surveyed the available techniques and data streams, arrived at the prioritization of textual analysis of journal/log entries and of interactive task discourse (in email, chat, and transcribed speech), and then went on to demonstrate promising sensitivity in the tools via analysis of pre-existing, historical data sources. While investigators showed individual and temporal variations with anecdotal correspondence to events, no independent data about the writers’ emotional states existed for validation of the text analysis techniques. The second year was targeted at transitioning the promising NIPSSA techniques found with the first year’s work on historical data to validation studies with newly collected “live” data from ongoing experiments in analog environments, particularly the Flight Analog Research Unit Bed Rest Study Campaign 11 conducted at the University of Texas Medical Branch.

The third project year was devoted to completing the bed rest analog journal study, while continuing to participate in a four-month crew habitat study in the Hawaii Space Exploration Analog and Simulation (HI-SEAS) and began participation in an eight-month HI-SEAS study collecting both journal and crew-ground textual interaction messages (with corresponding survey data). Finally, techniques for audio data collection and then transcriptions were developed in the Human Exploration Research Analog (HERA), from which investigators obtained and analyzed journal, survey, and text and speech interaction data from four separate week-long missions.

In the fourth and final year, investigators completed analyses of the HERA transcription data, and performed cross-analog analyses illustrating the robustness of their techniques. In the HERA study, they collected more than 160,000 minutes of captured audio recordings across four mission and transcribed large portions of this to enable examination of automated processing of interactive speech data. In all three analogs, investigators collected participant journals and daily surveys to cross validate their automated assessment techniques.

RESULTS:
The results show that automated textual analysis of subjects’ free form journals can reliably replace at least some forms of attitude and emotion surveys since the automated journal analyses regularly correlated significantly with subjects’ own survey ratings of their emotional positivity/negativity, and their focus on past/present/future across all three of the analog studies. Correlations between their attitudes about the study and about their physical well-being, as well as their focus on themselves versus others, were also repeatedly significant. Furthermore, there is evidence that automated evaluation of journal entries may do a better job of assessing participant attitudes than do daily observers: a comparative analysis between the automated assessments and subjects’ own survey responses versus the survey assessments of the subject by a nurse showed that automated analyses did a better job at predicting subjects’ survey responses.

Investigators also demonstrated the speed and flexibility of their approaches by rapidly producing multiple after-the-fact analyses of elements of participants’ attitudes and emotions throughout the study including analyses of the effects of exercise and of testosterone treatments on subjects’ emotions and attitudes about sleep and food. Further, by examining the correlates of positive or negative mentions of a word group such as food, eating, or specific food items investigators can provide suggestive evidence about how a specific individual or group thinks about that topic (that food is comforting and tied to nostalgia and social contacts or that it is a source of concern about body image and health). The flexibility to perform post hoc and deep, individualistic analyses proved to be a particularly useful capability and a strong distinguisher from survey questions.

In addition to examining journals, investigators developed techniques for examining interactive dialogue during tasks and daily activities. This form of communication is more immediate and less pre-meditated than journal entries and, therefore, is expected to be a less guarded but more transitory source of attitudes and emotions. Investigators have detected significant differences in the overall emotional valence of the different crews, of valence for differing tasks among the different crews, and of varying (and differing) drivers for those emotional sentiments among the crewmembers.

During debriefs with analog participants and operations personnel throughout this study, investigators have identified a number of recommendations for the use of the developed techniques that are particularly relevant to long-duration missions. Among these are an intervention or advisory tool for crewmembers themselves (reflecting exhibited changes in mood or attitude), a “power level” and “team comfort/routine” indicator for tracking intra-crew dynamics, and an aid for ground researchers to glean attitude and topic focus information from mission and training debriefing sessions.

APPROACH:
The CRF was comprised of the following forms:

APPROACH:
Muscle power was assessed twice before and twice after bed rest by performing the vertical jump test on a ground reaction force plate platform. Subjects performed countermovement vertical jumps. The subjects were instructed to jump as high as possible, with their hands on their hips. Attempts were made to obtain three maximal jumps; however, fewer jumps were performed in the post-bed rest phase. Body mass, reaction force, and jump height were recorded during data collection and jump power was calculated.

RESULTS:
This experiment has concluded. Summarized results for this test aren't available.

OBJECTIVES :
The objective of this experiment was to determine the effects of an analog of long-duration space flight on neural structural alterations and assess associated impacts on cognitive and behavioral performance. This experiment performed structural and functional MRI brain imaging (fMRI) to identify the relationship between changes in participants' neurocognitive function and neural structural alterations following 70 days of head-down tilt bed rest. The central hypotheses were that measures of brain structure, function, and network integrity would change from pre- to post- bed rest to a greater extent than that observed in matched control subjects, but to a lesser extent than what was observed in crewmembers under the NASA funded flight study, “Spaceflight Effects on Neurocognitive Performance: Extent, Longevity, and Neural Bases” (NNX11AR02G).

This study had the following two specific aims:

1: Identify changes in brain structure, function, and network integrity as a function of 70 days head down tilt bed rest and characterize their time course.

2: Specify relationships between structural and functional brain changes and performance and characterize their time course.

APPROACH:

Specific Aim 1

The investigators acquired brain structural and functional images at two time points pre-, two time points during, and three time points post- bed rest in 18 individuals and 16 controls who were tested at 4 time points but otherwise went around their daily lives. The researchers hypothesized that bed rest participants would exhibit changes from pre- to post- the intervention that were significantly greater than those seen in control participants across the same time period. Scans conducted during and following bed rest characterized the time course of changes and recovery.

Specific Aim 2

The investigators administered a broad ranging battery of sensory, motor, and cognitive assessments at the time points described for Aim 1. The researchers hypothesized that bed rest participants would exhibit pre- to post-intervention decrements in sensorimotor performance. Additionally, for some measures and time points, the researchers expected that there might be no performance effects despite alterations in brain structure and function due to compensatory brain processes, which would be identifiable with neuroimaging approaches. The measures acquired can be categorized into behavioral assessments and brain imaging assessments. The behavioral tests measured outside of the scanner included: card and cube rotation tests of spatial working memory, digit symbol substitution test of processing speed, rod and frame test of visual bias, pegboard test of bimanual coordination, sensory organization test of vestibular-mediated balance, functional mobility test of obstacle course navigation, and vestibular evoked myogenic potential to assess vestibular function.

The neuroimaging tests of brain structure and function included: structural MRI to measure regional brain volumes and relative gray matter density, diffusion weighted scans (often referred to as DTI) to measure structural connectivity integrity, resting state functional MRI to measure functional connectivity integrity, and functional MRI to measure brain networks engaged during the performance of various tasks. The latter tasks included: imaging of the functional vestibular cortex, brain regions engaged during single and dual tasking of cognitive and motor behaviors, brain regions engaged during adaptation of pointing movements to perturbed visual feedback, and brain regions engaged for spatial working memory and foot tapping.

RESULTS :

The investigators found robust changes with bed rest in balance and functional mobility, replicating other studies that have previously reported sensorimotor declines. They also observed changes in brain gray matter volume, functional connectivity, and task based activation that were specific to the time period of the bed rest intervention, many of which were associated with the magnitude of behavioral change. Some metrics exhibited complete recovery by the last time point 12 days post bed rest, while others were trending towards recovery but had not yet returned to baseline levels.

A panel of assays was designed to monitor immune system dysregulation, viral reactivation, and physiological stress. These assays will be applied to a future ISS/Shuttle Supplemental Medical Objective (SMO). This assay panel is also appropriate to monitor the status and function of the immune system, viral reactivation, and physiological stress during ground-based analog studies. These assays will be included on all future bed rest campaigns for the purpose of monitoring the immune status of the participants. While bed rest is not the most appropriate model for space flight-associated immune dysregulation, it is possible that the various countermeasures proposed for evaluation during bed rest may affect immune function. For this reason, the immune function of the participants will be monitored.

APPROACH:
There have been comparatively few flight studies investigating the effect of space flight on the human immune system. Those studies that have been performed may be subdivided into the following categories: (A) in flight culture of immune cells; (B) postflight assessments of crewmembers; (C) in flight crewmember immune assessments. These data were recently reviewed by Dr. Gerald Sonnenfeld and are summarized as follows:

A. In flight culture of immune cells
Human studies have indicated that space flight changes human cell culture activities such as leukocyte blastogenesis, production of cytokines, and signal transduction of leukocytes. Studies on animal cell cultures have also shown altered cytokine production and macrophage hematopoesis and function.

B. Postflight assessments of crewmembers
Most human space flight immunologic studies have explored the effects of space flight on cell-mediated immunity. Inhibited mitogen-induced blastogenesis of leukocytes has been observed in cells obtained from astronauts and cosmonauts after the Apollo-Soyuz test project, Skylab, Space Shuttle and Soyuz flights. Altered leukocyte subset distribution, altered cytokine production and altered natural killer (NK) cell activity have also been found to be altered immediately postflight.

C. In flight assessments of crewmembers
Precious few studies have been performed using astronaut subjects during space flight. Delayed hypersensitivity skin tests to common recall antigens were inhibited during short term and long term space flights. On Space Shuttle mission STS-71 a novel device for staining whole blood samples with fluorescent antibodies was flight tested using three MIR-18 crewmembers as subjects. Blood was collected and stained at a single timepoint late in the mission. Only the bulk leukocyte and lymphocyte subsets were evaluated and no change was found in these crewmembers. Recently, an in flight assessment of latent viral reactivation was performed using flight-collected saliva samples. Latent viral reactivation is thought to directly correlate with diminished immune function. The data showed that latent herpesviruses reactivate during flight to high levels. This is important since persistent viruses have been associated with non-Hodkins lymphoma tumors. A short term space flight study on Shuttle assessed total antibody levels and found no change in total immunoglobulin levels, whereas a long-duration Soviet mission indicated small increases in total immunoglobulin levels.

In the investigator's previous studies of astronauts, investigators found altered peripheral leukocyte distribution, altered cytokine production profiles, elevated levels of latent viral reactivation and elevated levels of cortisol during or immediately following long and short duration space flight. In addition, significant increases in stress hormones (i.e., cortisol, catecholamines) were found after landing. Notably, investigators found increased shedding of Epstein-Barr virus (EBV) and cytomegalovirus (CMV), two medically important herpesviruses, during space flight along with evidence of decreased cellular immunity. These increases in stress hormones directly correlated with CMV and EBV reactivation. Thus, latent herpesvirus reactivation in these astronauts may have resulted from both direct (i.e., stress hormones) and indirect (i.e., decreased immune function) mechanisms stemming from launch and landing acceleration. These results underscore the need to determine the causes underlying immune suppression in space in order to develop countermeasures.

RESULTS:
In general, subjects did not display altered peripheral leukocyte subsets, constitutive immune activation, altered T cell function, or significant latent viral reactivation (EBV, VZV). Levels of constitutively activated T cells (CD8+/CD69+) and virus-specific T cells (CMV and EBV) decreased during the study. Cortisol levels (plasma and saliva) did not vary significantly during 90-day bed rest.

Conclusions: These data demonstrate the absence of significant immune system alteration and physiological stress during 90-day bed rest, and establish control data against which future studies (including countermeasures) may be compared.

APPROACH:
Early bed rest sessions measured balance control performance before and after bed rest using the Equitest Platform and protocol similar to that used on many short duration space flight crewmembers and currently required for all returning crewmembers. Each bed rest subject was assessed both before and after bed rest.

Slight changes in protocol introduced MCT and changed the test name to CDP. Motor coordination, sensory integration, and balance control performance was measured before and after bed rest using the NeuroCom EquiTest Computerized Dynamic Posturography system. This protocol was similar to what is currently required for all returning long-duration crewmembers. Each subject completed at least two pre-bed rest test sessions ( approximately 10 days and 1 day before bed rest) and up to three post-bed rest tests. An additional pre-bed rest test was performed after the second test but prior to head down in order to establish an accurate baseline.

During these sessions, the subject stood on a movable, force-sensing, support surface and within the movable visual enclosure of the EquiTest system. Movements of the support surface and/or visual enclosure, under precise computer control, were used to modify the sensory conditions and/or to impose unexpected perturbations. The SOTs assessed the subject’s ability to make effective use of visual, vestibular, and somatosensory information for maintaining upright stance. During some trials, the support surface and/or visual surround were moved in relation to the subject’s sway, referred to as sway-referencing. Postural sway was measured during 20 second trials, including combinations of somatosensory conditions (fixed-support, sway-referenced support) and visual conditions (eyes open, eyes closed, sway-referenced vision). The primary outcome variable was the Equilibrium (EQ) score derived from the subject’s peak-to-peak antero-posterior sway during each trial relative to a theoretical stability limit of 12.5 degrees. A subject swaying to the limits of stability received a very low score. The highest possible score was 100, which indicated no sway. A score of zero was assigned to all falls/stopped trials. Postural performance was repeated with head movements which were made in the pitch plane at plus or minus 20 degrees, paced by a sinusoidal auditory tone at 0.33Hz with eyes closed, and a fixed-support or sway-referenced support surface. The subject was also challenged by sudden base-of-support perturbations (forward and backward translations). Perturbations were presented sequentially at randomly varied intervals. The primary outcome variable for perturbations was path length which is the distance the subject’s center of pressure traveled from the time of perturbation to the time of stability. The position of the head and other body segments were monitored using an Xbus Master motion tracking system (Xsens Technologies B.V., Enschede, and The Netherlands) which, in conjunction with the posturography system, was used to determine the type of strategy the subject was using to maintain balance. The subjects were instrumented with three electrocardiogram (ECG) electrodes for every test session and data (ECG/heart rate) was displayed. However, it was only on BR+0 that an Advanced Cardiac Life Support (ACLS) medical monitor was used to monitor the ECG/heart rate data for test termination criteria. Testing was nominally conducted twice before bed rest to achieve an accurate baseline and up to three times after bed rest.

The test conditions were:

1. Standard eyes open Romberg test-visual surround and support surface fixed
2. Standard eyes closed Romberg test-support surface fixed
3. Sway-referenced visual surround with fixed support surface
4. Sway-referenced support surface with fixed visual surround
5. Sway-referenced support surface with eyes closed
6. Dynamic head tilt with fixed support
7. Dynamic head tilt with sway-referenced support
8. Translation: base of support moves underneath, dependent on height of subject (forward and backward)

RESULTS:
This experiment has concluded. Summarized results for this test aren't available.

APPROACH:
This study utilized the dual-energy x-ray absorptiometry (iDXA) instead of the Hologic DXA hardware. Bone densitometry was performed using a General Electric Lunar whole-body densitometer located at John Sealy Hospital at UTMB, Galveston. This iDXA device can distinguish between hard tissue (bone) and soft tissue. Soft tissue can be distinguished further as either lean tissue or fat. Subjects participated in scans of the following regions: whole body, lumbar spine, proximal femurs (hips), and forearm. The subjects were scanned in triplicate for the pre- and in-bed rest sessions; the follow-up (6-month and 12-month) sessions were single scans.

RESULTS:
This experiment has concluded. Summarized results for this test aren't available.

OBJECTIVES:

Campaign 11 utilized 70 days of six degrees head-down bed rest. This study consisted of 13 days of pre bed rest for the non-exercise group and 21 days of pre bed rest for the exercise group, as well as 14 days of post bed rest. Head-down tilt bed rest relieves longitudinal gravitational loading of the cardiovascular, bone, and muscle systems. Healthy subjects exposed to prolonged bed rest experience some of the adaptive physiological responses and associated deconditioning seen in astronauts exposed to prolonged weightlessness. Campaign 11 onsisted of the integration of standard measures and visual monitoring with investigator study protocols. The objective of the Integrated Resistance and Aerobic Training (iRATS) was for subjects to perform six days per week of exercise training that consisted of a combination of high intensity resistance and aerobic exercise in order to maintain cardiovascular fitness and muscular strength and function during bed rest.

APPROACH:

Prior to the start of bed rest, subjects followed a schedule of resistance and aerobic exercise training five days per week to familiarize themselves with the equipment and protocols. These exercise sessions were individualized based on fitness and comfort level with the equipment. The goal of the pre-bed rest training period was to “ramp-up” the subjects to the full integrated resistance and aerobic training prescription and identify loads and speed settings for the in-bed rest training sessions. The subject also performed a stretching exercise regimen during exercise sessions, with the aid of an exercise physiologist.

During bed rest, subjects performed supine resistance training and continuous and interval aerobic exercise six days per week. The resistance exercise and continuous aerobic exercise that occur on the same day were separated by at least four hours. Resistance exercise sessions were performed using an in-house designed squat machine and modified commercial off-the-shelf (COTS) equipment. The resistance training sessions consisted of a variety of squat, heel raise, leg press and leg curl exercises. The aerobic exercise sessions were completed using a supine cycle ergometer and vertical treadmill. At least two-thirds of the aerobic exercise sessions were performed on the treadmill.

Resistance Exercise Sessions:
First 27 subjects: Resistance exercise was performed three days per week, every other day using a prone leg curl, horizontal leg press, and horizontal squat machine (i.e. HEF). A standard warm-up protocol was conducted for the lower body prior to exercise. The resistance exercise sessions consisted of a variety of squat, hamstring curl, heel raise and leg press exercises. The protocol varied so that a “HEAVY,” “MEDIUM,” and “LIGHT” day of exercise was performed during the week. The pre-bed rest exercise sessions were used to familiarize the subjects with the exercise equipment, teach subjects proper form, and determine individualized loads to be used during bed rest. The in-bed rest sessions were performed to maintain muscular strength and function during bed rest.

Last 8 subjects: Squat exercises previously performed on the Horizontal Squat Device were performed on the M-MED. Leg press, heel raise, and hamstring curl previously performed on their specific devices were then performed on the M-MED.

Aerobic Exercise Sessions:
First 27 subjects: Aerobic exercise sessions were completed on the supine cycle ergometer and the Standalone Zero-Gravity Locomotion Simulator (sZLS). A minimum of two-thirds of the total aerobic sessions were performed on the sZLS and the balance was performed on the cycle ergometer. For some subjects, the sZLS or the supine cycle may not be suitable for all aerobic protocols due to fitness levels or comfort levels. In these situations the Exercise Physiology researchers coordinated with the bed rest schedulers to meet the subject’s needs.

During the pre-bed rest and bed rest phases, the continuous aerobic exercise sessions were performed on the same day as the resistance training sessions and were separated by at least four hours. Interval aerobic exercise sessions were performed three times per week on non-resistance exercise days.

Last 8 subjects: Rowing exercise replaced the running and cycling exercises currently performed on the sZLS and supine cycle. Rowing was performed as interval and continuous sessions.

RESULTS:

The SPRINT protocol mitigated bed rest-induced muscle and cardiac deconditioning regardless of the exercise device used. Molecular markers of bone did not change in the sedentary or exercise groups. Peak aerobic capacity was maintained from pre- to post-bed rest in all exercise groups similarly, whereas significant declines were observed in the sedentary group (~10%). Significant interaction effects between the sedentary group and all exercise groups were observed for muscle performance including leg press total work, isokinetic upper and lower leg strength, vertical jump power, and maximal jump height as well as muscle size.

APPROACH:
Plasma volume was measured by the carboxyhemoglobin rebreathing method. The test subject breathed into a mouthpiece into which 60 cc of carbon monoxide (CO) was injected. In addition, blood draws were completed before and 10 minutes after CO administration.

RESULTS:
This experiment has concluded. Preliminary results are available.

Interim results were published from Campaign 3 using thirteen subjects which were studied before and during bed rest. Statistical analysis was limited to the first 49-60 days of bed rest and compared to pre-bed rest data. Ultrasound data were collected on vascular and cardiac structure and function. Tilt testing was conducted for 30 minutes or until presyncopal symptoms intervened. Plasma volume was significantly reduced by day seven of bed rest. Flow-mediated dilation in the leg was significantly increased at bed rest day 49. Arterial responses to nitroglycerin differed in the arm and leg, but did not change as a result of bed rest. Anterior tibial artery intimal-medial thickness markedly decreased at bed rest days 21, 35, and 49. Several cardiac functional parameters, including isovolumic relaxation time (73 ms to 85 ms at day 7) and myocardial performance index, were significantly increased during bed rest. There was a trend for decreased orthostatic tolerance following 60 day of bed rest. Over all the data suggest that bed rest altered cardiovascular structure and function in a pattern similar to short-duration spaceflight. Additionally, the vascular alterations were primarily seen in the lower body, while vessels of the upper body were unaffected.

During the artificial gravity (AG) pilot study it was concluded that AG can mitigate some aspects of bed rest-induced cardiovascular deconditioning, including orthostatic intolerance and aerobic power. Mechanisms of improvement were not cardiac-mediated, but likely through improved sympathetic responsiveness to orthostatic stress.end>