Abstract
To investigate single motor unit (SMU) firing patterns of the inferior head of the human lateral pterygoid muscle (IHLP) during sustained isometric contractions, and to examine IHLP fatigability. In 5 subjects, EMG was recorded from the right IHLP during generation of horizontal isometric mandibular force towards left side. Subjects tracked a target on an oscilloscope, slowly increasing the force to 25% of maximum voluntary contraction, and then maintained that force for 120 s (endurance task). Subjects rested for 30 s after each test, and three 10s recovery tests were performed every 30 s (recovery task). Fatigue data were obtained from 23 SMUs. Twelve of 23 SMUs (52.2%) continued to fire throughout the 120 s, and each subject had at least one of these units. These units were classified as tonic pattern (T-unit). The firing rate of 6 of the 12 T-units (50.0%) decreased gradually with time. Comparison of the mean firing rate and coefficient of variance (CV) of interspike interval (ISI) of the 12 T-units between pre-fatigue, post-fatigue and the three recovery tasks showed that the mean firing rate decreased and CV of ISI increased after fatigue. Mean firing rate and CV of ISI recovered after 30 s of rest after the endurance task. The firing patterns of IHLP units changed with the passing of time during sustained isometric contractions leading to fatigue.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.