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Influence of muscle contraction and jaw movement speed on the estimation of chewing force from elevator muscle EMG
Author(s) -
PRÖSCHEL P.,
RINNE H.,
MORNEBURG T.
Publication year - 2002
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1046/j.1365-2842.2002.01026_17.x
Subject(s) - mastication , isometric exercise , bite force quotient , masticatory force , chewing gum , electromyography , biting , masseter muscle , swallowing , orthodontics , physical medicine and rehabilitation , chemistry , medicine , anatomy , dentistry , physical therapy , biology , ecology , food science
Recent studies have shown that an additional muscle activity (AMA) in chewing was responsible for excessive masticatory forces that had been estimated from isometric bite force–activity relations. Our aim was to test the thesis that this AMA could be identical to the speed‐dependent ‘anticipatory activity’ that was found in symmetrical jaw closing (Abbink et al. , 1999). In this case, forces estimated from EMG should be realistic for slow mastication, but should strongly increase with faster chewing movements. In 56 dentate volunteers the activities of bilateral masseter and anterior temporal muscles were measured during (a) right‐sided chewing, (b) right‐sided isometric clenching on a bite fork with alternating loads. These biting tasks were carried out with slow, habitual and fast contraction/movement speeds (30, 64, 102 cycles min −1 ). Masticatory forces were estimated for each speed by putting activities found in task (a) into bite force/activity relations obtained from task (b). In slow and habitual mastication, activities of the working side masseter were equal and exceeded the corresponding clenching activities by factors of 2·8 and 2·4, respectively ( P < 0·001). Consequently, forces estimated from slow (680 N) and habitual (695 N) chewing did not differ significantly and were unrealistically high. These estimated forces and hence the corresponding AMAs did not depend on the speed movement in the same way as the anticipatory activity described in Abbink et al. (1999) . In contrast, forces estimated from fast chewing (811 N) were significantly higher ( P < 0·001) and corresponding AMAs qualitatively behaved like anticipatory activities. In conclusion, the AMA in chewing could be explained by anticipatory muscle activity for high movement speeds. In slow and habitual chewing however, the AMA may contain amounts of activity with a different origin .