DYNAMICS OF THE SIT-TO-STAND MOVEMENT

The strategies of the sit-to-stand movement are investigated by descri bing the movement in terms of the topology of an associated phase diag ram. Kinematic constraints are applied to describe movement sequences, thus reducing the dimension of the phase space. This dimensional redu ction allows us to apply theorems of topological dynamics for two-dime nsional systems to arrive at a classification of six possible movement strategies, distinguished by the topology of their corresponding phas e portrait. Since movement is treated in terms of topological structur e rather than specific trajectories, individual variations are automat ically included, and the approach is by nature model independent. Path ological movement is investigated, and this method clarifies how subtl e abnormalities in movement lead to difficulties in achieving a stable stance upon rising from a seated position.