Involuntary clenching is common during physical exercise; therefore, the purposeof this study was to elucidate the relationship between stomatognathic function and physical exercise as well as role and mechanism of involuntary teeth clenching during physical exercise.
In 15 healthy, fully dentate males (mean age 26.5±2.1), electromyographic activities from jaw closing (JM), sternocleidomastoid, biceps brachial (BB), and rectus femoral (RF) muscles; mandibular positions; and muscle strength during both isometric elbow flexion and knee extensionexercises were recorded and analyzed.
From the analysis of electromyographic activities and mandibular position, the subjects were divided into two groups, Clenching group (n=9) and Non-clenching group (n=6). The subjects in the Clenching group showed involuntary clenching during the exercise and their mandibular positions were located at the inter-cuspal position. The onset of electromyographic activity of JM was earlier than that of the agonist (BB, RF) in the 7 subjectsof the Clenching group. In the Clenching group, both elbow flexion and knee extension strength with involuntary clenching were lowered when voluntary mouth opening was directed during the exercise.
These results suggested that stomatognathic function and physical exercise had an interdependent relationship and involuntary clenching during physical exercise could be explained by a so-called feedforward mechanism.
