Qualitative analysis of arm motion in gravity variation
- Paper number
IAC-05-A1.1.07
- Author
Mr. Frédéric Meyer, Ecole Polytechnique Fédérale de Lausanne, Switzerland
- Coauthor
Mr. Gregory Chollet, Switzerland
- Coauthor
Mr. Adrian Gutknecht, Switzerland
- Coauthor
Mr. Nicolas Wiederecht, Switzerland
- Year
2005
- Abstract
While under natural terrestrial conditions, the sensory organs interact in a highly adaptive fashion; the changing gravitational conditions lead to potential errors in the perception affecting equilibrium and spatial orientation.
In daily life activity, two main problems are to be solved: the posture balance and the organization of movement. A precise reaching movement involves a complex coordination between head, eyes, upper limb and hand. The environment constraints alter the motor performance. When the gravitation factors change, the central nervous system has to adapt and must learn to compensate gravity variation.
During different gravitational constraints the stabilization of the arm during a movement cannot be performed in the same way as in normal gravity, which may cause profound changes in motor coordination patterns. Gravity differences influence both the vestibular system as the proprioceptive information. Exposure to weightlessness may disturb the normal input-output relationships of the afferent and efferent system. Combining the reaction time, the movement time and the signature of movement may give some information about the strategies of motor learning and control.
One question that has remained unanswered is whether the time course of the learning-related changes in movement parameters is similar for all parameters, in particular in gravitational variations.
The experiment was designed to determine: beginitemize item The movement signature, which gives the time-related parameters (duration of acceleration, duration of deceleration, and movement duration) and amplitude-related parameters (peak acceleration, peak deceleration, peak velocity), - and the kinematics of movement. item The pointing movement, witch inform about the accuracy and duration of movement. item The time between stimulus and answer (beginning of movement), which gives the reaction time, and should be related to attention cost and tiredness. enditemize
This protocol should allow to find out how long it takes for the brain to adapt to quick gravitational variations and, if it is possible, to memorise these adaptations so as to be able to act faster (learning effect) and to be more accurate in an altered gravitational state.
The objective of our experiment was to understand the subjacent mechanisms of postural and motor adaptations used for adapting the movement to gravitational constraints. In daily motor activities and different sports situations the ability to adapt quickly to different repetitive constraints could be trained using the same protocol in different environment. It should be of interest for astronot’s, pilot’s or sailors’ training to manage the perceptual visual and vestibular conflicts.
By performing our experiment during the 7th ESA student parabolic flight campaign, we could test, observe and mesure the reaction under different gravity factors (0, 1 and 1.8). Gravity being the most important reference in human motricity, differences in mouvement precision were noticed and recorded. The results have outlined a reaction time difference as well as a movement accuracy loss. The effects of fatigue and stress also have to be taken into account when analising these results.
- Abstract document
- Manuscript document
IAC-05-A1.1.07.pdf (🔒 authorized access only).
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