Classifying lower limb dynamics in Parkinson's disease.

To classify lower limb dynamics in patients with Parkinson's disease (PD), we conducted a clinical study by using pedaling exercise.Twenty-seven patients with idiopathic PD were included in this study. We measured rotational velocities of pedals during pedaling movements with a newly developed ergometer. The velocity waveforms exhibited different characteristics among patients, which could be categorized into four different clusters. In cluster 1, the amplitude on each side was constant and the relative phase was locked at 180 degrees. The pattern was the same as seen in normal subjects. In cluster 2, the amplitude on each side was constant, but the relative phase was locked at 90 degrees. In cluster 3, the amplitude on each side was modulated, and the relative phase drifted monotonously from 0 to 360 degrees during pedaling cycles. In cluster 4, the amplitude on each side was synchronously and irregularly modulated, and the relative phase fluctuated with intermittent spike-like decrement. In order to evaluate, the correlation between pattern and severity of PD, we divided 13 patients, who underwent measurement of pedaling patterns more than three times, into three groups, and found that the abnormal coordination pattern correlated with the presence of freezing phenomenon in patients with PD. Our clinical analysis may contribute in analyzing and classifying the dynamics of PD.