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| Author(s): |
Andréa Cristina de Lima
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola de Educação Física e Esportes (EEFE/BT) |
| Defense date: | 2009-04-29 |
| Examining board members: |
Luis Augusto Teixeira;
José Angelo Barela;
Luis Mochizuki
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| Advisor: | Luis Augusto Teixeira |
| Abstract | |
This study aimed to investigate the reactive components of postural adjustments in response to displacements of the basis of support, disturbing body balance, as a function of a concomitant manual execution of a supra-postural task and uncertainty about the perturbation direction. Sixteen young adults of both genders (M = 26,3 years; SD = 2,6) participated in the study. The supra-postural task consisted of equilibrating a cylinder on a tray (constraint), whose performance was assessed through cylinder displacement. The performance on stance was evaluated as a function of a combination of uncertainty of direction of postural perturbation (anterior or posterior) and the constraint imposed by the supra-postural task, requiring equilibrium of the cylinder or maintenance of a tray in a horizontal orientation. Performance on stance was assessed through electromyographic analysis of anterior and posterior muscles of the right leg and kinematics of the main joints involved in postural e supra-postural adjustments. The results showed that the supra-postural task in predictable perturbations decreased the activation latency of agonistic muscles and diminished the manual displacement in the supra-postural task. The constraining supra-postural task induced differential adjustments in the ankle, knee, hip and shoulder in comparison with the condition without constraint. The results suggest that the restrictive supra-postural task induced a more automatic postural control to rapidly react to perturbations, generating more efficient postural adjustments. Thus, the present results suggest that the constraining supra-postural task induced more automatic responses. These results indicate that the control of a supra-postural task is integrated with the maintenance of upright stance in situations of balance perturbation. Moreover, this integration was shown to be dependent on predictability of direction of postural perturbation. So, the main conclusion drawn from our results is that the constraint imposed by the supra-postural task influences reactive neurophysiological responses related to postural control, which are enhanced by postural perturbation predictability (AU) | |