Aging affects several skills, such as gait and posture. Balance during gait is a critical factor in determining the quality of life, but it is complex to be evaluated. Tests with this purpose have been developed for clinical practice, but they are not usually sensitive to discriminate intermediate balance levels. Walking on a balance beam involves the reduction of the base of support, accuracy on the foot placement and a small rise in the height at which the gait is performed, which causes greater difficulty than just walking on the ground. Since mechanical (i.e., arms position) and cognitive factors may also influence beam walking performance, the understanding of the effects of these factors may contribute to the development of adequate balance tests. Equally important is to understand how the older adults organize their motor activity to walk in an unstable context, such as the beam walking. Muscle coordination involves the use of flexible combinations of motor modules to produce a motor behavior that can be evaluated based on consistency, distinction, and separation of these modules. Aging can cause great variability in these coordination patterns and reorganization of motor modules. Thus, this study aims to investigate the effects of age, arm configuration and cognitive task on the muscular organization during the beam walking. Fifteen young and 15 older adults will walk over a line on the ground and on the beam with a width defined based on Study 1. Thirty-nine markers will be positioned at specific anatomical points, and the Vicon system will track their displacements together with 14 electromyography electrodes that will monitor the muscle activity of the right leg and trunk. Participants will walk with free arms and arms crossed on the chest, with and without the presence of the cognitive task (sequential subtraction by 3). It will be computed the spatial-temporal walking parameters (step length, duration and speed, and duration of the single and double support), the distance traveled in the beam, the margin of dynamic stability and the motor modules parameters. It will be used analyzes of variance to investigate the effect of the factors manipulated on the walking performance and motor modules. The level of significance for statistical analyzes will be 0.05.
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