Locomotor function after long-duration space flight: effects and motor learning during recovery

Abstract

Astronauts returning from space flight and performing Earth-bound activities must rapidly transition from the microgravity-adapted sensorimotor state to that of Earth's gravity. The goal of the current study was to assess locomotor dysfunction and recovery of function after long-duration space flight using a test of functional mobility. Eighteen International Space Station crewmembers experiencing an average flight duration of 185 days performed the functional mobility test (FMT) pre-flight and post-flight. To perform the FMT, subjects walked at a self selected pace through an obstacle course consisting of several pylons and obstacles set up on a base of 10-cm-thick, medium-density foam for a total of six trials per test session. The primary outcome measure was the time to complete the course (TCC, in seconds). To assess the long-term recovery trend of locomotor function after return from space flight, a multilevel exponential recovery model was fitted to the log-transformed TCC data. All crewmembers exhibited altered locomotor function after space flight, with a median 48% increase in the TCC. From the fitted model we calculated that a typical subject would recover to 95% of his/her pre-flight level at approximately 15 days post-flight. In addition, to assess the early motor learning responses after returning from space flight, we modeled performance over the six trials during the first post-flight session by a similar multilevel exponential relation. We found a significant positive correlation between measures of long-term recovery and early motor learning (P < 0.001) obtained from the respective models. We concluded that two types of recovery processes influence an astronaut's ability to re-adapt to Earth's gravity environment. Early motor learning helps astronauts make rapid modifications in their motor control strategies during the first hours after landing. Further, this early motor learning appears to reinforce the adaptive realignment, facilitating re-adaptation to Earth's 1-g environment on return from space flight.

Changes in Toe Clearance During Treadmill Walking After Long-Duration Spaceflight

“…However, personal observation and the results from the other half of this protocol, the Functional Mobility Test (FMT), indicate otherwise ( 35 ). In the FMT, crewmembers negotiated an " obstacle course, " while walking on mediumdensity foam to provide an unstable walking surface.…”

“…This retrospective study will address only kinematic toe clearance results from the fi rst part, the integrated treadmill locomotion test. The results of the second part, the functional-mobility obstacle course test, are outside the scope of this paper and have been addressed elsewhere ( 35 ).…”

Parallels between astronauts and terrestrial patients – Taking physiotherapy rehabilitation “To infinity and beyond”

“…This has implications for astronauts who may experience central changes due to altered sensory feedback. Central reinterpretation of sensory input impacts postflight gait and balance (Mulavara et al, 2010;Wood et al, 2015). Altered proprioceptive feedback can affect joint moments and power generation during gait, plus poor postural stability and increased visual dependency (Mazzaro et al, 2005;van der Linden et al, 2010.…”

Exposure to an extreme environment comes at a sensorimotor cost

“…Different studies on human adaptation to space flight reveal a clear and serious disruption of sensorimotor function, 3,4 including postural and oculomotor control systems. 5–10 Astronauts returning to a 1G environment from both short (8–15 days) and long (>160 days) duration space flight report difficulty with locomotion upon return to Earth to include ataxic gait, a tendency to fall to the outside when turning corners, 11 a cautious gait that involves keeping the arms raised as if to prevent a fall, and use of a widened base of support with reduced step frequency. 12,13 Many have a reluctance to move their head.…”