BACKGROUND: Literature proposes three hypotheses for impaired movement execution in hyper-G. The present study attempted to discriminate between these hypotheses by comparing kinematic characteristics and final accuracy of pointing movements in different gravity levels. METHOD: Subjects pointed without seeing their hand at targets presented before, during and after exposure to hyper-G. RESULTS: After factoring out movement amplitude, peak vertical velocity and the skewness of velocity profiles tended to increase, while movement duration tended to decrease with increasing G-level. Further, final response position was slightly less modulated by target position in hyper-G than in normal-G. CONCLUSION: Although not all findings reached statistical significance, the observed pattern of results corroborates the hypothesis (2) that the motor system re-interprets hyper-G as increased arm weight.
BACKGROUND: Literature proposes three hypotheses for impaired movement execution in hyper-G. The present study attempted to discriminate between these hypotheses by comparing kinematic characteristics and final accuracy of pointing movements in different gravity levels. METHOD: Subjects pointed without seeing their hand at targets presented before, during and after exposure to hyper-G. RESULTS: After factoring out movement amplitude, peak vertical velocity and the skewness of velocity profiles tended to increase, while movement duration tended to decrease with increasing G-level. Further, final response position was slightly less modulated by target position in hyper-G than in normal-G. CONCLUSION: Although not all findings reached statistical significance, the observed pattern of results corroborates the hypothesis (2) that the motor system re-interprets hyper-G as increased arm weight.
Authors: Ajitkumar P Mulavara; Brian T Peters; Chris A Miller; Igor S Kofman; Millard F Reschke; Laura C Taylor; Emily L Lawrence; Scott J Wood; Steven S Laurie; Stuart M C Lee; Roxanne E Buxton; Tiffany R May-Phillips; Michael B Stenger; Lori L Ploutz-Snyder; Jeffrey W Ryder; Alan H Feiveson; Jacob J Bloomberg Journal: Med Sci Sports Exerc Date: 2018-09 Impact factor: 5.411