Motor imagery of body movements that can't be executed on Earth.

BACKGROUND: Before participating in a space mission, astronauts undergo parabolic-flight and underwater training to facilitate their subsequent adaptation to weightlessness. A quick, simple and inexpensive alternative could be training by motor imagery (MI).

OBJECTIVE: An important prerequisite for this training approach is that humans are able to imagine movements which are unfamiliar, since they can't be performed in the presence of gravity. Our study addresses this prerequisite.

METHODS: 68 young subjects completed a modified version of the CMI test (Schott, 2013). With eyes closed, subjects were asked to imagine moving their body according to six consecutive verbal instructions. After the sixth instruction, subjects opened their eyes and arranged the segments of a manikin into the assumed final body configuration. In a first condition, subjects received instructions only for moving individual body segments (CMIground). In a second condition, subjects received instructions for moving body segments or their full body (CMIfloat). After each condition, subjects were asked to rate their subjective visual and kinesthetic vividness of MI.

RESULTS: Condition differences emerged for the CMI scores and for the duration of correct trials with better performance in the CMIground condition. Condition differences were also represented for the subjective MI performance.

CONCLUSION: Motor imagery is possible but degraded when subjects are asked to imagine body movements while floating. This confirms that preflight training of MI while floating might be beneficial for astronauts' mission performance.