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Neville Hogan. Wang, Shuo, S.B. Massachusetts Institute of Technology Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering 2014-01-09T19:51:35Z 2014-01-09T19:51:35Z 2013 http://hdl.handle.net/1721.1/83755 864821447 Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013. Cataloged from PDF version of thesis. Includes bibliographical references (pages 20-21). This study reports the effects of ankle muscle fatigue on ankle mechanical impedance. It suggests that decreasing ankle impedance with muscle fatigue may contribute to an increased probability of ankle injury. If confirmed, this observation may have important athletic, military and clinical implications. The experiment was designed to induce fatigue in the tibialis anterior and triceps surae muscle groups by instructing subjects to perform isometric contractions against a constant ankle torque generated by a backdrivable robot, Anklebot, which interacts with the ankle in two degrees of freedom. Median frequencies of surface electromyographic (EMG) signals collected from tibialis and triceps surae muscle groups were evaluated to assess muscle fatigue. Using a standard multi-input and multi-output stochastic impedance identification method, multivariable ankle mechanical impedance was measured in two degrees of freedom under muscle fatigue. Results indicate that ankle mechanical impedance decreases in both the dorsi-plantarflexion and inversion-eversion directions under tibialis muscle fatigue. However, the effect of triceps surae on ankle mechanical impedance is uncertain since the current experimental protocol could not effectively induce fatigue in triceps surae. by Shuo Wang. S.B. 21 pages eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Mechanical Engineering. Ankle mechanical impedance under muscle fatigue Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="868f4732-8120-48d8-aba5-31b6fa5801f6"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Ankle mechanical impedance under muscle fatigue</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2013</PublicationDate> <Authors> <Author> <DisplayName>Wang, Shuo, S.B. Massachusetts Institute of Technology</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Mechanical Engineering.</Keyword> <Abstract>This study reports the effects of ankle muscle fatigue on ankle mechanical impedance. It suggests that decreasing ankle impedance with muscle fatigue may contribute to an increased probability of ankle injury. If confirmed, this observation may have important athletic, military and clinical implications. The experiment was designed to induce fatigue in the tibialis anterior and triceps surae muscle groups by instructing subjects to perform isometric contractions against a constant ankle torque generated by a backdrivable robot, Anklebot, which interacts with the ankle in two degrees of freedom. Median frequencies of surface electromyographic (EMG) signals collected from tibialis and triceps surae muscle groups were evaluated to assess muscle fatigue. Using a standard multi-input and multi-output stochastic impedance identification method, multivariable ankle mechanical impedance was measured in two degrees of freedom under muscle fatigue. Results indicate that ankle mechanical impedance decreases in both the dorsi-plantarflexion and inversion-eversion directions under tibialis muscle fatigue. However, the effect of triceps surae on ankle mechanical impedance is uncertain since the current experimental protocol could not effectively induce fatigue in triceps surae.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>