Sit-to-Stand Trainer: An Apparatus for Training "Normal-Like" Sit to Stand Movement

Sit-to-stand (STS) transfer training is probably the most demanding task in rehabilitation. We have developed an innovative STS trainer that offers variable levels of mechanical support and speeds of STS transfer. In a group of neurologically intact individuals we compared kinematics, kinetics and electromyography (EMG) patterns of STS transfer assessed in three experimental conditions with increasing degree of mechanical support (MIN STS-T, MED STS-T, and MAX STS-T) to natural, unassisted STS movement (NO STS-T). The resulting ankle, knee, hip joint and trunk angles in experimental conditions MED STS-T and MIN STS-T were very similar to experimental condition NO STS-T. Vertical ground reaction forces and EMG patterns in the tibialis anterior, quadriceps and hamstrings show a clear trend toward "normal" patterns as the level of mechanical support from the device is progressively reduced. We have further tested the feasibility of the STS trainer in five stroke subjects at two levels of support showing that increased voluntary effort is needed when the support is reduced. Based on these results we conclude that negligible constraints are imposed by the device on a user's STS transfer kinematics, which is an important prerequisite for considering clinical use of the device for training in neurologically impaired.