The effects of external cues on ankle control during gait initiation in Parkinson's disease.

The present study investigated the effects of external cues on motor control of the ankle joint during gait initiation in patients with Parkinson's disease (PD) and in age-matched healthy subjects. The soleus H-reflexes were recorded during self-generated and cue-triggered gait initiation. The tibialis anterior muscle burst during cue-triggered gait initiation was found to be significantly larger than that during self-generated gait initiation in both groups. External cues significantly increased soleus H-reflex depression during gait initiation in PD patients, although this significant increase was not present in healthy subjects. These findings indicate that external cues affect motor control of the extensor muscle of the ankle joint during gait initiation in PD patients.