Microsoft Word - ASB 2010_STS _Masa_

Different movement strategies are used to achieve sit-to-stand (STS) task, depending on balance control ability of the individual. These strategies can be classified by horizontal momentum of the whole body center of mass (COM) and its location relative to the base of support (BOS) [1]. The combinations of COM velocity and position for which loss of balance can be avoided were described as the feasible stability region [2], which would allow us to distinguish the strategy. The COM acceleration also plays an important role. Inability to properly generate COM acceleration would lead to a poor momentum control and result in imbalance. Examining COM acceleration, in addition to its velocity, would provide further insights into balance control during the movement. The purpose of this study was to establish a region of stability using COM acceleration and to characterize age-related differences in the control of COM during the STS movement. Strategies used for the control of COM motion between healthy young and elderly adults were compared using regions of stability derived by COM velocity and acceleration (ROSv and ROSa, respectively).