Figure. Left panel shows time of onset of symptoms for the subjects in the healthy (n = 50), TMD (n= 50), and WAD (n = 50) groups who reported fatigue (A), or pain (B) and failure point (C) for the subjects who failed to complete the task. Numbers in parenthesis indicate the number of subjects in each group who reported symptoms, and vertical lines indicate median values. Right panel shows percentage of subjects in each group who reported fatigue (D) and pain (E) or who discontinued the task (F). P-values were calculated for group differences by the Chi-square test.