EMG reactivity and oral habits among young adult headache sufferers and painfree controls in a scheduled-waiting task.

Previous research has shown that patients with facial pain exhibit a pattern of physiological and behavioral reactivity to scheduled-waiting tasks that may help account for the development of facial pain. The present study extended this line of research by examining the psychophysiological reactivity of headache sufferers in a similar task. A total of 34 frequent headache sufferers screened by International Headache Society (IHS) criteria and 13 painfree controls completed a psychophysiological assessment consisting of 4 phases (adaptation, free-play, scheduled-play, and recovery) that included a scheduled-waiting condition (scheduled-play) designed to produce adjunctive behavior. Masseter and frontalis EMG were measured continuously during each phase and self-reported oral habits and pain ratings were collected following each phase. A significant interaction and group effect was found on frontalis EMG, with the headache group exhibiting elevated EMG levels across the phases, whereas the control group exhibited increasing EMG levels that peaked during the scheduled-play phase. Only a significant phase effect was found on masseter EMG, with the highest EMG levels recorded during the scheduled-play phase for both groups. In addition, a significant phase effect was found on self-reported oral habits data. Overall, these results provide general support for the adjunctive behavior effect, but the predicted difference in magnitude between the groups was not found.