Efeitos da idade e do foco de atenção no desempenho e na coordenação da tarefa de passar de sentado para de pé.

Abstract

Sit-to-stand (STS) is essential to independence in activities of daily living. However, STS performance tends to decline with aging, becoming even more challenging when it is associated with secondary tasks such as holding a cup. STS control may be improved by cognitive strategies such as directing the focus of attention. For a variety of motor tasks, focusing attention on the environmental effects of movement (i.e. an external focus) leads to more efficient and effective motor performance than focusing attention on the movement itself (i.e. an internal focus). The purpose of this study was to investigate how STS while holding a cup is controlled and how control is affected by age and attention focus. 21 healthy old and 26 young adults performed STS while holding a cup with the non-dominant hand under two attention focus conditions: external and internal. STS performance variables were quantified. STS coordination was investigated with the uncontrolled manifold (UCM) analysis. Young participants tilted the cup less and showed smoother horizontal motion of the body center of mass (CoM) than older adults, but older participants showed smoother vertical motion of the CoM and smoother horizontal and vertical motion of the cup. Older adults also showed significantly higher values of both VUCM and VORT for the horizontal and vertical dimensions of the CoM. However, younger participants showed higher synergy indices for the horizontal and vertical position of the CoM than older participants. Therefore, it seems that, to stabilize the CoM, older adults coordinate their joint motions in more flexible, but also more unstable patterns. Attention focus instructions did not affect task performance or coordination. It is possible that well-trained tasks learned spontaneously in childhood, like STS, are less prone to the negative effects of an internal focus or to the positive effects of an external focus.