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Assessment of neuromuscular response characteristics at the knee following a functional perturbation

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
David H. Perrin, Provost and Executive Vice Chancellor (Creator)
Sandra J. Shultz, Associate Professor (Contributor)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: Previous research indicates that both the extent and timing of muscular activation at the knee can be influenced by muscle activity state, joint angle, weight-bearing status and trunk position. However, little research to date has evaluated protective neuromuscular response times and activation patterns to an imposed perturbation with the knee joint in a functional, weight-bearing stance. Hence, we designed a lower extremity perturbation device to produce a sudden, forward and either internal or external rotation moment of the trunk and femur relative to the weight-bearing tibia. Surface electromyography (EMG) recorded long latency reflex times of the medial and lateral quadriceps, hamstring and gastrocnemius muscles in 64 intercollegiate lacrosse and soccer players in response to both internal and external rotation perturbation. We found the gastrocnemius fired significantly faster that the hamstring, which in turn fired significantly faster than the quadriceps. There was also a significant difference in activation times of the medial and lateral hamstring not found for the quadriceps or gastrocnemius muscles. Our findings confirmed that reactive neuromuscular responses following this functional perturbation differ markedly from those previously reported using seated, partial weight-bearing and/or uni-planar models under relaxed conditions.

Additional Information

Publication
Journal of Electromyography and Kinesiology, 10:159-170
Language: English
Date: 2000
Keywords
Electromyography, Neuromuscular control, Anterior cruciate ligament, Long latency reflex, Reaction time