Switching of movement direction is central to Parkinsonian bradykinesia in sit-to-stand

Kit Yi Mak, Christina W.Y. Hui-Chan

Research output: Journal article publicationReview articleAcademic researchpeer-review

32 Citations (Scopus)


Patients with Parkinson's disease (PD) are known to manifest slowness in movements. We sought to identify the particular kinematic and kinetic disorders that contribute to the slowness in performing sit-to-stand in these patients. Two interrelated studies were carried out. In the first study, 20 patients with PD and 20 control subjects were instructed to perform sit-to-stand at a natural speed. In the second study, 15 control subjects were instructed to simulate the slower speed of sit-to-stand of the patients identified in the first study. Kinematic and kinetic data were recorded by a PEAK motion analysis system and two force platforms. The results showed that patients with PD generated smaller peak horizontal and vertical velocities during the task. They took a longer time to complete each individual phase as well as the whole movement of sit-to-stand. Patients also produced smaller peak hip flexion and ankle dorsiflexion joint torques and had prolonged time-to-peak torques from sit-to-stand onset. When control subjects simulated the patients' speed of sit-to-stand, there was no difference in all the kinematic and kinetic data between groups. The only exception was that they exhibited a shorter transition time between peak horizontal velocity (flexion phase) and seat-off (extension phase) than the patients. This study demonstrated that the slowness of PD patients during sit-to-stand at a natural speed could be attributed to inadequate peak hip flexion and ankle dorsiflexion torques, a prolonged torque production, as well as a difficulty in switching from the flexion to extension direction during sit-to-stand. As the latter difficulty persisted when the control subjects performed the task at a speed similar to that of the patients, our findings suggest that a fundamental problem of patients with Parkinson's disease could be a switch between movement directions.
Original languageEnglish
Pages (from-to)1188-1195
Number of pages8
JournalMovement Disorders
Issue number6
Publication statusPublished - 1 Nov 2002


  • Bradykinesia
  • Center of mass
  • Parkinson's disease
  • Sit-to-stand

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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