Fig. 6
The relationship between the number of synchronized muscles and the tremor amplitudes in shoulder and elbow joints in PD subjects. The correlations between tremor amplitudes in a elbow flexion, b shoulder flexion, c shoulder abduction, and d shoulder rotation and the number of synchronized muscles are evaluated by exponential regression. Different subjects are indicated with different markers and the error bars indicate the standard deviation of tremor amplitudes of each subject. The R2 (squared correlation coefficients) and P values are given in the figure. Tremor amplitudes in joints are strongly correlated with the number of synchronized muscles except for shoulder flexion that shows only a mild correlation