Are joint torque models limited by an assumption of monoarticularity?

• Published in: Journal of applied biomechanics Vol. 28; no. 5; p. 520
• Main Authors: Lewis, Martin G C, King, Mark A, Yeadon, Maurice R, Conceição, Filipe
• Format: Journal Article
• Language: English
• Published: United States 01.11.2012
• Subjects: Adult; Ankle Joint - physiology; Biomechanical Phenomena; Computer Simulation; Female; Humans; Knee Joint - physiology; Male; Muscle Strength Dynamometer; Range of Motion, Articular; Torque
• ISSN: 1543-2688
• DOI: 10.1123/jab.28.5.520

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Isovelocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex MJ dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary.