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Influence of knee joint angle on muscle properties of paralyzed and nonparalyzed human knee extensors
Author(s) -
Gerrits Karin H.,
Maganaris Constantinos N.,
Reeves Neil D.,
Sargeant Anthony J.,
Jones David A.,
de Haan Arnold
Publication year - 2005
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20328
Subject(s) - torque , knee joint , spinal cord injury , knee flexion , physical medicine and rehabilitation , anatomy , electromyography , medicine , spinal cord , physics , surgery , psychiatry , thermodynamics
Muscles of individuals with a spinal cord injury (SCI) exhibit an unexpected leftward shift in the force (torque)–frequency relationship. We investigated whether differences in torque–angle relationships between SCI and able‐bodied control muscles could explain this shift. Electrically stimulated knee‐extensor contractions were obtained at knee flexion angles of between 30° and 90°. Torque–frequency relationships were obtained at 30°, 90°, and optimum angle. Optimum angle was not different between groups but SCI‐normalized torques were lower at the extreme angles. At all angles, SCI muscles produced higher relative torques at low stimulation frequencies. Thus, there was no evidence of a consistent change in the length of paralyzed SCI muscles, and the anomalous leftward shift in the torque–frequency relationship was not the result of testing the muscle at a relatively long length. The results provide valuable information about muscle changes occurring in various neurological disorders. Muscle Nerve, 2005