Switching of movement direction is central to parkinsonian bradykinesia in sit‐to‐stand

Abstract

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 inter-related 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.

The influence of Nordic Walking training on sit-to-stand transfer in Parkinson patients

“…Nikfer et al report that patients with PD try to decrease the duration of the unstable transitional phase to reduce the requirements on balance [13]. Another opinion is that PD patients have problems in movement transition and therefore their second phase is extended [11]. In the present study, both groups reduced the duration of the momentum-transfer phase, which allows us only to speculate that with better stability they would be able to manage the transition more quickly.…”

“…This may be due to the apparent advancement of PD in these subjects, especially the increase of hypokinesia. The more pronounced hypokinesia may lead to more Table 3 Means, standard deviations, differences within pairs, and differences between groups of UPDRS A (n = 6), UPDRS B (n = 5), and CO (n = 11 deficits in recruitment patterns and co-contraction and result in smaller hip flexion and ankle dorsiflexion joint torques during STS [11,12,22]. Similar to CO, UPDRS A showed a slightly faster performance of STS after training.…”

“…Differences in STS movement between PA and CO have been analysed in the past [11][12][13]15,20,21]. These studies identified a variety of interactive variables for the performance of STS in healthy subjects, as well as in subjects with neurological disorders.…”

“…This transition from a stable seated, to a relatively unstable upright position requires adjusted muscle contractions of the lower limbs and trunk, as well as control of equilibrium and stability [11][12][13]. Previous studies have assessed coordinative and controlling aspects of joint displacement, trunk movement and balance during STS performance in PA.…”

“…several strategies that enable patients to perform STS and compensate for disease-related impairments [11,[13][14][15]. The effect of training on selected biomechanical measures of STS function in PA has not been reviewed before.…”