Are joint torque models limited by an assumption of monoarticularity?
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.
Loughborough University, Loughborough, UK.
Martin G C
MG
Lewis
Mark A
MA
King
Maurice R
MR
Yeadon
Filipe
F
Conceição
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D053581:Muscle Strength Dynamometer; D016059:Range of Motion, Articular; D019415:Torque