title: Task-related electromyographic spectral changes in the human masseter and temporalis muscles.
abstract: The masticatory muscles differ in their fiber 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 from the anterior and posterior temporalis muscles of nine adult subjects. At a bite force level as low as 25 N, the mean power frequency (MPF) values of the posterior temporalis were significantly lower than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude, whereas the MPF values of the anterior and posterior temporalis did not change significantly. The MPF values were significantly influenced by the direction of bite force. The observed changes of MPF are possibly related to the recruitment of different fiber types, and support the concept that the masticatory muscles behave heterogeneously.
authors.affiliation: Department of Orthodontics, University of Naples Federico II, Italy. farella@unina.it
authors.forename: Mauro
authors.initials: M
authors.lastname: Farella
authors.forename: Theo
authors.initials: T
authors.lastname: Van Eijden
authors.forename: Michela
authors.initials: M
authors.lastname: Baccini
authors.forename: Ambra
authors.initials: A
authors.lastname: Michelotti
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001732:Bite Force; D004576:Electromyography / Q000295:instrumentation; D005246:Feedback; D006801:Humans; D016014:Linear Models; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D015999:Multivariate Analysis; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D016011:Normal Distribution; D012044:Regression Analysis; D012815:Signal Processing, Computer-Assisted; D013703:Temporal Muscle / Q000502:physiology*; D014159:Transducers