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 space flight. The set of functional tasks making up the FTT included 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 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.
This study had the following specific aims:
Results demonstrate that for Space Shuttle, ISS, and bed rest (control and exercise) subjects, functional tasks requiring a greater demand for dynamic control of postural equilibrium (i.e., fall recovery, seat egress/obstacle avoidance during walking, object translation, jump down) showed the greatest decrement in performance. Functional tests with reduced requirements for postural stability such as hatch opening, ladder climb, manual manipulation of objects, and tool use showed little reduction in performance. These changes in functional performance were paralleled by similar decrements in sensorimotor tests designed to specifically assess postural equilibrium and dynamic gait control.
The muscle function data showed reductions in lower body muscle performance metrics in both space flight 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 space flight 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 space flight subjects indicating that body support unloading experienced during space flight plays a central role in postflight alteration of functional task performance. Additionally, ISS crewmembers who walked on the treadmill with higher pull-down loads had enhanced postflight 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 space flight and bed rest data indicate that an elevated heart rate was required to maintain arterial blood pressure during performance of multiple functional tasks. Space flight 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.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Expedition 22||11/30/2009||03/18/2010||109 days|
|Expedition 23||03/18/2010||06/01/2010||75 days|
|Expedition 24||06/01/2010||09/25/2010||117 days|
|Expedition 25||09/24/2010||11/25/2010||31 days|
|Expedition 26||11/26/2010||03/16/2011||111 days|
|Expedition 27||03/14/2011||05/23/2011||70 days|
|Expedition 28||05/23/2011||09/15/2011||115 days|
|Expedition 29||09/16/2011||11/21/2011||40 days|
|Expedition 30||11/14/2011||04/27/2012||166 days|
|Expedition 31||04/27/2012||07/01/2012||65 days|
|Expedition 32||07/01/2012||09/16/2012||78 days|
|Expedition 34||11/18/2012||03/15/2013||117 days|
|Expedition 35||03/15/2013||05/13/2013||58 days|
|Expedition 36||05/13/2013||09/10/2013||166 days|
|Expedition 37||09/10/2013||11/10/2013||61 days|
|Expedition 38||11/10/2013||03/10/2014||120 days|
|Expedition 39||03/10/2014||05/13/2014||64 days|
|Expedition 40||05/13/2014||09/10/2014||133 days|
|Expedition 41||09/10/2014||11/09/2014||29 days|
|Expedition 42||11/10/2014||03/11/2015||121 days|
|Expedition 43||03/11/2015||06/10/2015||91 days|
|Expedition 44||06/10/2015||09/11/2015||93 days|
|Expedition 45||09/11/2015||12/11/2015||91 days|
|Expedition 46||12/11/2015||03/02/2016||82 days|