title: Joint torques during sit-to-stand in healthy subjects and people with Parkinson's disease.
abstract: OBJECTIVE
  To compare lower limb joint torques during sit-to-stand in normal elderly subjects and people with Parkinson's disease, using a developed biomechanical model simulating all phases of sit-to-stand.Design. A cross-sectional study utilizing a Parkinsonian and a control group.
  
  
  BACKGROUND
  Subjects with Parkinson's disease were observed to experience difficulty in performing sit-to-stand. The developed model was used to calculate the lower limb joint torques in normal elderly subjects and subjects with Parkinson's disease, to delineate possible causes underlying difficulties in initiating sit-to-stand task.
  
  
  METHODS
  Six normal elderly subjects and seven age-matched subjects with Parkinson's disease performed five sit-to-stand trials at their self-selected speed. Anthropometric data, two-dimensional kinematic and foot-ground and thigh-chair reactive forces were used to calculate, via inverse dynamics, the joint torques during sit-to-stand in both before and after seat-off phases. The difference between the control and Parkinson's disease group was analysed using independent t-tests.
  
  
  RESULTS
  Both control and Parkinson's disease groups had a similar joint kinematic pattern, although the Parkinson's disease group demonstrated a slower angular displacement. The latter subjects produced significantly smaller normalized hip flexion torque and presented a slower torque build-up rate than the able-bodied subjects (P<0.05).
  
  
  CONCLUSIONS
  Slowness of sit-to-stand in people with Parkinson's disease could be due to a reduced hip flexion joint torque and a prolonged rate of torque production.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong. rsmmak@polyu.edu.hk
authors.forename: Margaret K Y
authors.initials: MK
authors.lastname: Mak
authors.forename: Oron
authors.initials: O
authors.lastname: Levin
authors.forename: Joseph
authors.initials: J
authors.lastname: Mizrahi
authors.forename: Christina W Y
authors.initials: CW
authors.lastname: Hui-Chan
mesh_terms: D000843:Ankle Joint / Q000503:physiopathology; D006621:Hip Joint / Q000503:physiopathology; D007596:Joints / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology; D008954:Models, Biological; D009068:Movement; D009333:Neck / Q000503:physiopathology; D010300:Parkinson Disease / Q000503:physiopathology*; D011187:Posture; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D019415:Torque