Nível de estabilização na resposta a perturbações imprevisíveis: efeitos sobre o feedback corrente e o feedforward

Abstract

The objective of this study was to investigate if subjects with three different levels of stabilization of the performance adapt in different way to unpredictable perturbations introduced after the movement on set. Twenty-four volunteers were divided into three experimental groups: pre-stabilization group (GP), stabilization group (GE) and super-stabilization group (GS). The experiment was conducted in two phases: pre-exposure and exposure. During the preexposurephase, only GE and GS practiced the task of throwing the dart, doingan arm swinging movement in back-front direction, to a target with the center positioned at 2.5m far from the throwing area. The groups were differentiated on the criterion of performance to finish the practice at this phase: for GE it was doing a block of three trials in a row with the scores of the target ranging from 28 to 40; for GS the criterion of performance was six blocks of three trials in a row with the score of the target ranging from 28 to 40. The exposure phase had the participation of three groups, GE, GS and GP and all the volunteers made 158 trials of which 18 were inserted unpredictable perturbations after the beginning of the movement. A pair of turned on diodes indicated which target should be reached. In some pre-established trials, but without knowledge of the subjects, after the movement on set, the diodes of the target positioned 2.5 mfar from the throwing area turned off and the diodes from the one of the other two targets, with the center 2.0 m and 3.0 m far from the throw area, turned on. It was analyzed measures of performance (score) and of feedforward and current feedback (kinematic measures). The results indicated that none of the groups managed to adapt to the perturbations and that GS used more feedforward than GP.