Objectives:
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).
Conclusion:
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.