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:
This experiment has concluded. Summarized results for this test aren't available.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Campaign 1||08/29/2004||11/21/2004||84 days|
|Campaign 11||05/11/2011||12/15/2014||3 years, 7 months, 4 days|
|Campaign 17||05/11/2011||02/12/2012||278 days|
|Campaign 3||02/20/2005||04/14/2010||5 years, 1 month, 25 days|
|Campaign 5||04/30/2006||12/23/2007||1 year, 7 months|