Article

In order to evaluate the effects of uncertainty about direction of mechanical
perturbation and supra-postural task constraint on postural control, young adults
had their upright stance perturbed while holding a tray in a horizontal position.
Stance was perturbed by moving forward or backward a supporting platform,
contrasting situations of certainty versus uncertainty of direction of
displacement. Increased constraint on postural stability was imposed by a
supra-postural task of equilibrating a cylinder on the tray. Performance was
assessed through EMG of anterior leg muscles, angular displacement of the main
joints involved in the postural reactions and displacement of the tray. Results
showed that both certainty on the direction of perturbation and increased
supra-postural task constraint led to decreased angular displacement of the knee
and the hip. Furthermore, combination of certainty and high supra-postural task
constraint produced shorter latency of muscular activation. Such postural
responses were paralleled by decreased displacement of the tray. These results
suggest a functional integration between the tasks, with central set priming
reactive postural responses from contextual cues and increased stability demand.
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Langue : ANGLAIS