THE RELATIONSHIP BETWEEN JAW ELEVATOR MUSCLE SURFACE ELECTROMYOGRAM AND SIMULATED FOOD RESISTANCE DURING DYNAMIC CONDITION IN HUMANS

In six human subjects, electromyograms (EMGs) of the masseter and temp oral muscles were recorded bilaterally during experiments in which the subjects made rhythmic open-close movements. The closing phase was co unteracted by a variable external force on the mandible. Variables of the force (amplitude, time integral and work) and variables of the cor responding EMG bursts (duration, peak amplitude and time integral) wer e computed for each open-close cycle. Linear regression analyses were used to determine the strength of the relationship between each EMG va riable and each force variable. By step-wise multiple regression analy sis the EMG variables predicting the force variables were determined. Although there was a highly significant and positive correlation (P < 0.0005), the average coefficients of linear correlation varied from 0. 46 to 0.82. The strongest relationship was observed between the time i ntegrals of the force and EMG in the interval between the onset of the burst and the onset of occlusion. It was suggested that to assess mus cle force during chewing, the time integral of EMG bursts should be co mputed.