Premium
Task‐related electromyographic spectral changes in the human jaw muscles
Author(s) -
FARELLA M.,
VAN EIJDEN T. M.,
BACCINI M.,
MICHELOTTI A.
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_27.x
Subject(s) - masticatory force , bite force quotient , force transducer , electromyography , masseter muscle , anatomy , temporalis muscle , orthodontics , medicine , physics , physical medicine and rehabilitation , acoustics
The masticatory muscles differ in their fibre type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study surface EMG activity was picked up from the masseter, and anterior and posterior temporalis muscles of nine adult subjects. Direction and magnitude of bite force were recorded using a three‐component force transducer. Bite forces were exerted in five different directions: vertical, forward, backward, to the right and to the left of the subject. Non‐vertical forces were kept at an angle of 15° from the vertical. Force levels of 25, 50, 100 and 200 N were exerted in each of the investigated directions. Data collected were analysed by means of a regression model for repeated measurements. It appeared that the mean power frequency (MPF) values of the posterior temporalis were significantly lower ( P < 0·01) than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude ( P < 0·001) whereas the MPF values of the anterior and posterior temporalis did not change significantly ( P > 0·05). The MPF values were significantly influenced by the direction of bite force ( P < 0·01). The observed changes of MPF are possibly related to the recruitment of different fibre types and support the concept that the masticatory muscles behave heterogeneously .