Maximum voluntary clenching (MVC) will be recorded for four seconds three times with a three-minute interval between readings. After five minutes of rest, EMG activity will be recorded for 15 seconds three times successively each under the following conditions: i) Resting position: the subject will be instructed to relax and maintain the maxillary and mandibular teeth out of contact; ii) maximum voluntary clenching (isometric): the subject will be instructed to clench as hard as possible; and iii) chewing (isotonic): the subject will be instructed to lightly and systematically bite down on the two strips of parafilm positioned bilaterally in time with a metronome calibrated at 60 beats per minute. A three-minute interval between readings will be given for the EMG signals recorded in the resting position and during chewing and a five-minute interval between readings will be used for MVC.