NOTE: End date changed to 11/30/2014 per HRP information (Ed., 3/31/15)

NOTE: Gap changes per IRP Rev E (Ed., 3/18/14)

NOTE: End date changed to 5/5/2015 and Risk/Gaps changed per JSC MTL dtd 11/11/11 (Ed., 11/18/2011)

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

The FTT was comprised of seven functional tests and a corresponding set of interdisciplinary physiological measures targeting the sensorimotor, cardiovascular and muscular adaptations associated with exposure to spaceflight. Both Shuttle and International Space Station (ISS) crewmembers as well as bed rest subjects participated in this study. Spaceflight data were collected in three sessions before flight, on landing day (Shuttle only), and 1, 6, and 30 days after landing. Bed rest subjects were tested three times before bed rest, immediately upon getting up after 70 days of 6° head-down bed rest, as well as 1, 6, and 12 days during the subsequent re-ambulation period. The bed rest analog allowed us to isolate the impact of body unloading without other spaceflight environmental factors on both functional tasks and on the underlying physiological factors that lead to decrements in performance, and then to compare those results with the results obtained in our spaceflight study.

Information obtained in this study will inform the design and implemention of countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with spaceflight.

In terms of Earth benefits this research will provide a better understanding of the underlying physiological mechanisms that contribute to changes in functional performance. For example, in the elderly population activities of daily living are often impaired by mutifactorial physiological causes. The information obtained from this interdisciplinary study will aid in identifying the relative contributions of sensorimotor, cardiovascular, and muscle function on comprehensive performance outcomes. This has direct application in the design of clinical interventions and rehabilitation programs that can target specific systems responsible for decline in functional performance.

The muscle function data showed reductions in lower body muscle performance metrics in both spaceflight groups and bed rest subjects who did not exercise. Bed rest subjects who performed an integrated high intensity interval-type resistance and aerobic training program while in bed showed significantly improved lower body muscle performance compared to bed rest controls and spaceflight subjects. However, resistive and aerobic exercise alone was not sufficient to mitigate decrements in functional tasks that require dynamic postural stability and mobility and point to the need for the addition of balance training to current in-flight countermeasures.

Bed rest subjects experienced similar deficits both in functional tests with balance challenges and in sensorimotor tests designed to evaluate postural and gait control as spaceflight subjects indicating that body support unloading experienced during spaceflight plays a central role in post-flight alteration of functional task performance. Additionally, ISS crewmembers who walked on the treadmill with higher pull-down loads had enhanced post-flight performance on tests requiring mobility. Taken together the bed rest and in-flight exercise training data point to the importance of providing increased body loading during in-flight treadmill and lower body resistive exercise.

Both spaceflight and bed rest data indicate that an elevated heart rate was required to maintain arterial blood pressure during performance of multiple functional tasks. Spaceflight data indicated that restoration of plasma volume alone did not prevent the elevated heart rate experienced while prone or standing during postflight testing. These data indicate that additional countermeasures are necessary to maintain central blood volume, prevent or reverse changes in peripheral vasoconstriction, and minimize the need for elevations in heart rate during various functional tasks.

These data demonstrate that an integrated countermeasure system should be composed of the following elements: 1) A high intensity interval-type resistance and aerobic exercise training program, 2) Balance/sensorimotor adaptability training, and 3) Individualized gradient compression garments (GCG) coupled with pre-landing fluid loading. Forward work will focus on follow-up bed rest and flight studies that incorporate these elements into an integrated interdisciplinary countermeasure system for future exploration class missions.

NOTE: End date changed to 11/30/2014 per HRP information (Ed., 3/31/15)

NOTE: Gap changes per IRP Rev E (Ed., 3/18/14)

NOTE: End date changed to 5/5/2015 and Risk/Gaps changed per JSC MTL dtd 11/11/11 (Ed., 11/18/2011)

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

Using a multivariate regression model we will identify which physiological systems contribute the most to impaired performance on each functional test. This will allow us to identify the physiological systems that play the largest role in decrement in functional performance. Using this information we can then design and implement countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with space flight.

In terms of Earth benefits this research will provide a better understanding of the underlying physiological mechanisms that contribute to changes in functional performance. For example, in the elderly population activities of daily living are often impaired by mutifactorial physiological causes. The information obtained from this interdisciplinary study will aid in identifying the relative contributions of sensorimotor, cardiovascular, and muscle function on comprehensive performance outcomes. This has direct application in the design of clinical interventions and rehabilitation programs that can target specific systems responsible for decline in functional performance.

To date we have completed data collection on 7 Shuttle crewmembers and 12 ISS crewmembers.

The remaining ISS subject will return in May, 2014 completing the subject complement of 13.

Completed individual crewmember postflight data debriefs.

Completed crew Informed Consent Briefing for the 1-year ISS flight.

Selected to be featured in the 2011 Annual Report for the Human Research Program.

Completed and submitted the Shuttle Interim FTT Report (79 pages).

Presented Shuttle FTT data at the NASA/JSC Human System Risk Board (March 28, 2012).

Completed the Mid-Term Data Review (May 17, 2013).

To date we have completed 4 peer reviewed papers and 40 abstracts/presentations.

Forward work includes completing data collection on ISS subjects (n=13). Once all the data are collected we will be able to create a multivariate regression model to describe the relationship between the physiological changes associated with space flight and decrement in functional task performance along with a comparison of recovery rates between short and long-duration crewmembers. This will allow us to identify the prime physiological factors that contribute most to alteration in functional task performance. This information will then be used to inform the design of targeted countermeasure systems to mitigate these physiological changes leading to improved task performance.

NOTE: Gap changes per IRP Rev E (Ed., 3/18/14)

NOTE: End date changed to 5/5/2015 and Risk/Gaps changed per JSC MTL dtd 11/11/11 (Ed., 11/18/2011)

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

Using a multivariate regression model we will identify which physiological systems contribute the most to impaired performance on each functional test. This will allow us to identify the physiological systems that play the largest role in decrement in functional performance. Using this information we can then design and implement countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with space flight.

In terms of Earth benefits this research will provide a better understanding of the underlying physiological mechanisms that contribute to changes in functional performance. For example, in the elderly population activities of daily living are often impaired by mutifactorial physiological causes. The information obtained from this interdisciplinary study will aid in identifying the relative contributions of sensorimotor, cardiovascular, and muscle function on comprehensive performance outcomes. This has direct application in the design of clinical interventions and rehabilitation programs that can target specific systems responsible for decline in functional performance.

To date we have completed data collection on 7 Shuttle crewmembers and 7 ISS crewmembers (13 ISS crewmembers planned).

Six additional ISS subjects are either inflight or in the preflight data collection phase.

Completed individual crewmember postflight data debriefs.

Completed crew Informed Consent Briefings (ICB).

Selected to be featured in the 2011 Annual Report for the Human Research Program.

Completed and submitted Shuttle Interim FTT Report (79 pages).

Presented Shuttle FTT data at the NASA/JSC Human System Risk Board (March 28, 2012).

To data have completed 3 peer reviewed papers and 27 abstracts/presentations.

Summary of Preliminary Observations

1) Functional tests that required dynamic control of postural equilibrium to complete (Seat Egress and Walk, Recovery from Fall, Rock Translation, Jump Down) demonstrated the greatest postflight changes in performance. Functional Tests with reduced requirements for postural stability (Torque Generation, Ladder Climb) showed less reduction in performance. For these tests posture was stabilized while the task was being performed. In the Torque Generation Test posture was stabilized because the subject completed the task while gripping the hatch like wheel device. In the Ladder Climb Test postural instability was minimized because subjects performed the task with four points of stabilization (i.e. both hands and legs).

2) Sensorimotor tests sensitive to the vestibular component underlying postural and gait control showed the largest postflight alterations (Dynamic Posturography Test, Tandem Walk Test, Treadmill Locomotion/Dynamic Visual Acuity Test). Tests of fine motor control and force steadiness control did not change after space flight. Therefore, the observed changes in functional performance were linked to postflight alterations in vestibular function leading to decrement in performance for tasks with greater requirements for dynamic postural equilibrium control.

3) Astronauts showed postflight elevated heart rates and sympathovagal balance (an indication of the relative influence of the sympathetic and parasympathetic branches of the autonomic nervous system on the control of heart rate) during the Recovery from Fall/Stand Test while parasympathetic activity was decreased. This result indicates a postflight shift toward sympathetic activation and vagal withdrawal on R+0. Similarly, heart rate was consistently elevated during performance of all the other functional tests. There was no change in blood pressure at rest or during standing in the Recovery from Fall/Stand Test. There was also no change in plasma volume in this group of astronauts although previous investigators have reported that plasma volume is reduced after space flight. The lack of change in plasma volume for this study could have resulted from improved in-flight countermeasure compliance, stricter adherence to the fluid loading protocol, or medical intervention prior to testing. Importantly, the observations of elevated heart rate and altered autonomic responses during post-flight functional testing are more striking in that they are less likely to be linked solely to a decrease in plasma volume.

4) The muscle performance data indicate significant reductions in the leg press performance metrics of maximal isometric force, power and total work. Bench press total work was also significantly impaired, although maximal isometric force and power were not significantly affected. No overall changes were noted for measurements of central activation or force steadiness. The muscle performance data show reductions in lower body muscle performance metrics and these alterations are likely contributors to impaired functional tasks that are ambulatory in nature. Interestingly, no changes in central activation capacity were detected. Therefore, impairments in muscle function in response to short-duration space flight are likely myocellular rather than neuromotor in nature.

5) Forward work includes completing data collection on ISS subjects (n=13). Once all the data are collected we will be able to create a multivariate regression model to describe the relationship between the physiological changes associated with space flight and decrement in functional task performance along with a comparison of recovery rates between short and long-duration crewmembers. This will allow is to indentify the prime physiological factors that contribute most to alteration in functional task performance. This information will then be used to inform the design of targeted countermeasure systems to mitigate these physiological changes leading to improved task performance.

NOTE: End date changed to 5/5/2015 and Risk/Gaps changed per JSC MTL dtd 11/11/11 (Ed., 11/18/2011)

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

Using a multivariate regression model we will identify which physiological systems contribute the most to impaired performance on each functional test. This will allow us to identify the physiological systems that play the largest role in decrement in functional performance. Using this information we can then design and implement countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with space flight.

In terms of Earth benefits this research will provide a better understanding of the underlying physiological mechanisms that contribute to changes in functional performance. For example, in the elderly population activities of daily living are often impaired by mutifactorial physiological causes. The information obtained from this interdisciplinary study will aid in identifying the relative contributions of sensorimotor, cardiovascular, and muscle function on comprehensive performance outcomes. This has direct application in the design of clinical interventions and rehabilitation programs that can target specific systems responsible for decline in functional performance.

- To date we have completed data collection on 7 Shuttle crewmembers and 4 ISS crewmembers (13 planned).

- 7 additional ISS subjects in data collection phase.

- Completed all Shuttle crew individual data debriefs.

- Selected to be featured in the 2011 Annual Report for the Human Research Program.

- Completed and submitted Shuttle Interim FTT Report (79 pages).

- Presented Shuttle FTT data at the Human System Risk Board (March 28, 2012).

- To data have completed 2 peer reviewed papers and 23 abstracts/presentations

Summary of Preliminary Observations from Shuttle Subjects

1) Functional tests that required dynamic control of postural equilibrium to complete (Seat Egress and Walk, Recovery from Fall, Rock Translation, Jump Down) demonstrated the greatest postflight changes in performance. Functional Tests with reduced requirements for postural stability (Torque Generation, Ladder Climb) showed less reduction in performance. For these tests posture was stabilized while the task was being performed. In the Torque Generation Test posture was stabilized because the subject completed the task while gripping the hatch like wheel device. In the Ladder Climb Test postural instability was minimized because subjects performed the task with four points of stabilization (i.e. both hands and legs).

2) Sensorimotor tests sensitive to the vestibular component underlying postural and gait control showed the largest postflight alterations (Dynamic Posturography Test, Tandem Walk Test, Treadmill Locomotion/Dynamic Visual Acuity Test). Tests of fine motor control and force steadiness control did not change after space flight. Therefore, the observed changes in functional performance were linked to postflight alterations in vestibular function leading to decrement in performance for tasks with greater requirements for dynamic postural equilibrium control.

3) Astronauts showed postflight elevated heart rates and sympathovagal balance (an indication of the relative influence of the sympathetic and parasympathetic branches of the autonomic nervous system on the control of heart rate) during the Recovery from Fall/Stand Test while parasympathetic activity was decreased. This result indicates a postflight shift toward sympathetic activation and vagal withdrawal on R+0. Similarly, heart rate was consistently elevated during performance of all the other functional tests. There was no change in blood pressure at rest or during standing in the Recovery from Fall/Stand Test. There was also no change in plasma volume in this group of astronauts although previous investigators have reported that plasma volume is reduced after space flight. The lack of change in plasma volume for this study could have resulted from improved in-flight countermeasure compliance, stricter adherence to the fluid loading protocol, or medical intervention prior to testing. Importantly, the observations of elevated heart rate and altered autonomic responses during post-flight functional testing are more striking in that they are less likely to be linked solely to a decrease in plasma volume.

4) The muscle performance data indicate significant reductions in the leg press performance metrics of maximal isometric force, power, and total work. Bench press total work was also significantly impaired, although maximal isometric force and power were not significantly affected. No overall changes were noted for measurements of central activation or force steadiness. The muscle performance data show reductions in lower body muscle performance metrics and these alterations are likely contributors to impaired functional tasks that are ambulatory in nature. Interestingly, no changes in central activation capacity were detected. Therefore, impairments in muscle function in response to short-duration space flight are likely myocellular rather than neuromotor in nature.

5) Forward work includes completing data collection on ISS subjects (n=13). Once all the data are collected we will be able to create a multivariate regression model to describe the relationship between the physiological changes associated with space flight and decrement in functional task performance along with a comparison of recovery rates between short and long-duration crewmembers. This will allow is to identify the prime physiological factors that contribute most to alteration in functional task performance. This information will then be used to inform the design of targeted countermeasure systems to mitigate these physiological changes leading to improved task performance.

NOTE: End date changed to 5/5/2015 and Risk/Gaps changed per JSC MTL dtd 11/11/11 (Ed., 11/18/2011)

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

Using a multivariate regression model we will identify which physiological systems contribute the most to impaired performance on each functional test. This will allow us to identify the physiological systems that play the largest role in decrement in functional performance. Using this information we can then design and implement countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with space flight.

During this review period 13 presentations/abstracts related this project were completed at four international scientific meetings. These include:

18th IAA Humans in Space Symposium, Houston, TX April 11-15, 2011.

8th Symposium on the Role of the Vestibular Organs in Space, Houston, TX, April 8-10, 2011.

American College of Sports Medicine Annual Meeting, Denver, CO, May 31-June 4, 2011.

82nd Annual Scientific Meeting of the Aerospace Medical Association, Anchorage, AK, May 9-12, 2011.

NOTE: End date changed to 3/17/2014 (previously 9/30/13) per JSC (2/2010)

The functional test battery was designed to address high priority tasks identified by the Constellation program as critical for mission success. The set of functional tests making up the FTT include the: 1) Seat Egress and Walk Test, 2) Ladder Climb Test, 3) Recovery from Fall/Stand Test, 4) Rock Translation Test, 5) Jump Down Test, 6) Torque Generation Test, and 7) Construction Activity Board Test. Corresponding physiological measures include assessments of postural and gait control, dynamic visual acuity, fine motor control, plasma volume, orthostatic intolerance, upper and lower body muscle strength, power, fatigue, force control and neuromuscular drive. Crewmembers will perform both functional and physiological tests before and after short (Shuttle) and long-duration (ISS) space flight. Data will be collected on R+0 (Shuttle only), R+1, R+6 and R+30.

Using a multivariate regression model we will identify which physiological systems contribute the most to impaired performance on each functional test. This will allow us to identify the physiological systems that play the largest role in decrement in functional performance. Using this information we can then design and implement countermeasures that specifically target the physiological systems most responsible for the altered functional performance associated with space flight.

Functional Tests

The objective of this pilot study was to examine the reliability of our set of functional tests. To achieve this objective, 14 normal subjects were tested on the battery of functional tests on three separate sessions with a preceding familiarization session at least 2 days apart to determine if the performance metrics obtained from these functional tests display variations between the sessions that are within limits to detect a change after space flight. The duration of the reliability study was seven weeks and a total of 56 test sessions were completed. In addition to the primary data measures collected during the sessions, subjects were equipped with hardware that recorded electrocardiogram (EKG), blood pressure, electromyography (EMG), and body position data. These functional tests will become part of a larger suite of tests that include corresponding physiological measures that include assessments of vestibular function, dynamic visual acuity, fine motor control, postural and locomotor stability, plasma volume, orthostatic intolerance, upper and lower body muscle strength, power, fatigue, control and neuromuscular drive.

The following functional tests were conducted:

1) Seat Egress and Walk Test

The ability to egress from a seat, ambulate and avoid obstacles following landing will be assessed with the Seat Egress and Walk Test. For this test subjects were required to unbuckle a harness while in a seat and stand up. Testing occurred under two initial conditions: 1) with the seat upright; 2) with the seat positioned with its back to the floor. Immediately following egress from the seat, subjects walked through the obstacle course. After negotiating the portal and pylons, subjects walked up and down a sloped surface inclined at 18 degrees. The primary performance metric was time to complete the course.

2) Recovery from Fall/Stand Test

Impairment in the ability to get up from a prone position is one of the strongest independent risk factors associated with serious fall related injuries. For this test, subjects, were asked to lie down on a mat face down and then asked to stand up again as quickly as possible when a start command was given. The primary performance metric was time elapsed between presentation of the start command and the completion of the stand.

We have integrated into this test, a three-minute Stand Test designed to assess orthostatic intolerance in an operational context and gain physiological data describing underlying changes in cardiovascular function that contribute to orthostatic intolerance. Immediately upon standing up, subjects performed the Stand Test by taking a step onto the solid floor and maintained a quiet standing position for three minutes. Previous results from landing day tilt/stand tests indicate that three minutes should provide a reasonable measure of orthostatic tolerance while remaining within a non-syncopal period even for long-duration crewmembers. Continuous blood pressure was acquired with a Portapres (TNO Medical, Netherlands) ambulatory blood pressure monitor. High fidelity, 12-lead EKG was acquired with a Holter monitor (Mortara Instrument, Milwaukee, WI).

3) Rock Translation Test

While on the planetary surface astronauts will be required to carry objects (tools, equipment, rock samples) from one point to another. To simulate this task requirement subjects picked up one of three weights (6, 10, 20 lbs) that have handles to grip (CorBall, Power Systems Inc. Knoxville, TN) and carried the weight a distance of eight feet and placed it in a receptacle positioned at twenty inches above the floor. This procedure was repeated until all three weights were individually transferred to the receptacle. Then the subject returned each weight one-by-one to its original location. The primary performance metric was time to complete the entire task.

4) Torque Generation Test

Performance on the Torque Generation Test was assessed with the use of the BTE PrimusRS System (BTE Technologies, Hanover, MD). A wheel attachment was affixed to the PrimusRS to simulate a hatch-opening task. Subjects stood on the floor while performing the task under both isometric and isotonic conditions. For the isometric evaluation the wheel attachment was fixed and subjects were asked to apply as much torque as possible to rotate the wheel assembly. The PrimusRS recorded the torques during the session. In the isotonic portion of the assessment, a constant resistance was applied to the wheel attachment and the wheel was allowed to rotate. The resistance applied by the system was equal to 50% of the average peak torque obtained from the isometric trial. The subject was asked to turn the wheel as quickly as possible for a total time of 20 seconds. The primary performance metrics were peak torque and number of wheel turns in 20 seconds.

5) Ladder Climb Test

The ability to climb a ladder is an essential functional task related to entering or exiting into a planetary landing vehicle. Current landing vehicle designs (i.e. Lunar Surface Access Module) include ladders that extend from 20-28 rungs, so ladder climbing will be an early task performed by astronauts soon after landing on a planetary surface. To gain a better understanding of ladder climbing ability, we developed the Ladder Climb Test. To perform the Ladder Climb Test, subjects climbed a passive treadmill ladder (Jacobs Ladder, LLC, North Tonawanda, NY) at a self-generated pace until they completed 40 rungs. The primary performance metric was time to completion.

6) Construction Activity Board Test

To assess changes in the ability to perform manual assembly and repair tasks each subject completed a standard EVA training task. This task has been used previously to evaluate space suit designs and is used to train astronauts participating in actual EVA activities. While standing, subjects performed a variety of standard construction and assembly tasks including connecting hoses to receptacles. Subjects also used a cordless power tool to tighten bolts on a handle assembly. The primary performance metric was time to complete the entire set of manual tasks.

7) Jump Down Test

Astronauts may be required to jump down from landing vehicles, habitats and on uneven terrain during exploratory extravehicular activities (EVAs). Changes in this ability can lead to increased incidence of falling. Given the previously described changes in control of jumping and landing and the highly relevant operational nature of this task we designed a functional test to investigate jump down performance.

During the Jump Down Test, subjects used a two-footed hop to jump from a height of 30 cm and landed on a force plate to measure the peak vertical impact force on landing. (Kistler, model 9286A, Kistler Instruments, Winterthur, Switzerland). Force transducers, one under each foot, were used to determine the time that the subject leaves the platform. EMG was collected using a system developed by Delsys, Inc. (Bagnoli EMG systems, Delsys Inc., Boston, MA). Electrodes were placed on the major postural muscles (medial and lateral gastrocnemius, soleus, and anterior tibialis) on the subject’s left leg.

The first performance metric for the Jump Down Test was the Settling Time. This metric provides a measure of how quickly the postural control system can bring the body to steady state after impact following the jump. The other performance metric was the peak resultant force following landing. These metrics provide an overall indication of the efficacy of intersegmental coordination and muscular control mechanisms to produce an appropriate response to compensate for impact forces following landing. The two main EMG parameters obtained were: 1) the preparatory response latency with respect to the time the subject leaves the platform and, 2) Functional Stretch Reflex latency with respect to force plate impact. This test was repeated for total of three trials.

Conclusions

1) The main performance metrics obtained from the FTT functional tests were within limits to detect a change associated with space flight. Therefore, the functional test performance metrics are reliable indicators of postflight performance.

2) The signals obtained from the body motion sensors, EMG electrodes and the force plate were within the physiological range expected and the signal quality is such that the desired parameters can be extracted for analysis.

3) Excellent quality blood pressure data were obtained for the portions of the FTT that were designed to evaluate an orthostatic challenge. Additionally, heart rate data, and its derivatives were satisfactorily obtained for all but the Torque Generation Test.

Muscle Performance Tests

The goal of this pilot study was to examine the reliability of the muscle performance measures used in this study. Ten subjects completed a battery of lower- and upper-body neuromuscular performance tests on three separate occasions, with each session separated by at least 48 hours. The battery consisted of tests in the following order: 1) knee extension central activation; 2) knee extension force steadiness; 3) leg press maximal strength; 4) leg press maximal power; 5) leg press power endurance; 6) bench press maximal strength; 7) bench press force steadiness; 8) bench press maximal power; and 9) bench press power endurance. We determined that the muscle performance test battery could quickly and reliably assess diverse indices of neuromuscular performance.