Speed variation and resultant joint torques during sit-to-stand.

The purpose of this study was to test the hypothesis that a progressively faster speed of ascent requires significantly greater peak resultant joint torque (RJT) at major load-bearing joints of the lower limb during the sit-to-stand (STS) transfer. Eight healthy adults performed the STS at slow, natural, and fast speeds. A motion analysis system and two force platforms were employed to record kinetic data, and equations of motion were applied to compute the RJT for the ankle, knee, and hip. The results of the study supported the hypothesis that when the speed of ascent increased progressively, the peak hip flexion, knee extension, and ankle dorsiflexion RJTs increased disproportionately. However, the peak hip extension and ankle plantar flexion RJTs remained relatively constant across the range of the speeds. Implications for clinical practice pertaining to the timing and magnitude of RJT, as well as for interventions that emphasize the adaptive characteristics of movements, are suggested.