Influence of Customization of the Mouthpiece for Scuba Diving on Oro-facial Muscle Activities: a Preliminary Report.

Scuba diving is one of the most rapidly growing marine sports in Japan. Many divers continuously clench the mouthpiece for scuba diving (SD mouthpiece) during the dive, and experience unpleasant symptoms of fatigue of the temporomandibular joint or oro-facial muscles after the dive. The purpose of this study was to investigate the effect of customization of the labial flange and platform of the SD mouthpiece on oro-facial muscle activities during the dive by simulating the state of holding the SD mouthpiece under water. EMG activity of the anterior belly of temporal muscles, masseter muscles and orbicular oris muscles while holding the SD mouthpiece for 7 min was recorded and integrated value of muscle activity as a parameter of muscle activity with and without customization was compared in four male beginner divers (28±2 years). Muscle activity of temporal muscles increased when the labial flange was narrowed, that of masseter muscles decreased when the labial flange was widened or the platform was extended, and that of orbicular oris muscles increased when the labial flange was widened or the platform was shortened. These results suggested that customization of the SD mouthpiece may improve muscle activities while holding the mouthpiece for scuba diving. [ABSTRACT FROM AUTHOR]