Describing force patterns: a method for classifying sit-to-stand movement in elderly people.

The main contribution of this study is that it examined the sit-to-stand movements of elderly people and then established an assessment method to supplement the existing Berg Balance Scale for the risk of falling in elderly individuals. 36 elderly adults (M age = 69.9 yr., SD = 4.0) volunteered to participate in this study. Three key points of the sit-to-stand movement were confirmed as aspects of the ground reaction force: the onset, maximum ground reaction force, and seat-off. Based on the characteristics indicated by the force data, the sit-to-stand movement sequences of those who were evaluated at low fall risk with a Berg Balance Scale score between 41 and 55 were classified into three patterns: typical-modal, multimodal, and incompetent-modal patterns. With this increased accuracy, medical practitioners can determine more clearly those participants who require further immediate medical consultation and those that are not at risk of falling.

Evaluation of key points in the sit-to-stand movement using two force platforms.

Three key points of the sit-to-stand (STS) movement were confirmed as aspects of the ground reaction force (GRF): the onset, maximum GRF, and seat-off. 46 healthy subjects (M age = 22.2 yr., SD = 4.4) participated. During the STS movement, two vertical force platforms were used to measure the resultant GRF, defined as the whole-body force, and its two components, the buttock and leg GRFs. The onsets of the component GRFs identified the sequence of the important time points in the STS movement more precisely than the onset of the resultant GRF. Data showed that the maximum whole-body GRF, the maximum GRF of both legs, and seat-off appeared in sequence and not simultaneously.