Effects of physiotherapeutic exercise of the jaw on chewing movements in humans

Abstract

Physiotherapeutic exercise is used much less often for the management of temporomandibular disorders than for other chronic musculoskeletal pain conditions. This reduced use may be partly related to the uncertain effects of such exercises on the activation pattern of the jaw muscles. The current study aimed to clarify the effects of physiotherapeutic resistance exercise of the jaw on the path of masticatory movements. Fourteen normal volunteers were randomly divided into 2 groups, i.e., the exercise and control groups. The participants of both the groups underwent 2 sessions during which their jaw movements were recorded; the sessions were separated by a 10-min rest interval. During each session, the participants ingested a mouthful of cooked rice 5 times. In the exercise group, isometric resistance training was performed during the rest period; the subjects were asked to perform lateral jaw excursion against the opposing force created by their own fingers. The maximum amount of lateral deviation during chewing significantly increased only in the second session in the exercise group (p=0.028); the opening direction of the jaw in the frontal plane also changed significantly (p=0.028). No significant changes were observed in the control group. These findings may indicate that short-term resistance exercise can cause instantaneous changes in the muscle activation pattern of the jaw muscles during chewing. Further studies will be required to clarify the longitudinal effects of exercise training.