Electromyographic assessment of the activity of the masticatory using the agonist contract–antagonist relax technique (AC) and contract–relax technique (CR)

Proprioceptive neuromuscular facilitation (PNF) techniques are a group of therapeutic procedures that may be used to cause relaxation of muscles. Studies have found controversial results when applying these techniques. The aim of the present study was to evaluate the effectiveness of masticatory muscle relaxation through the use of the contract–relax technique (CR) when compared with the agonist contract–antagonist relax technique (AC).A convenience sample of 30 students was recruited for this study. The CR and the AC techniques were applied to the subjects in order to cause relaxation of the masticatory muscles. Electromyography activity of all muscles was registered. Two way ANOVA with repeated measures analysis demonstrated that both the AC technique and the CR technique did not decrease the EMG activity of masticatory muscles (P>0.05P>0.05). Instead, both techniques caused an increase in electromyographic activity of the masticatory muscles.Based on the results obtained from this study, both the CR and the AC techniques were not effective in causing relaxation of the masticatory muscles. The purported physiological mechanisms of PNF techniques, which stated that they act through reciprocal inhibition and autogenic inhibition causing muscular relaxation, are not supported by this study.