Estimating Torque-Angle Relations of Human Elbow Joint in Isovelocity Flexion Movements

Kenzo AKAZAWA
Ryuhei OKUNO

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E89-D    No.11    pp.2802-2810
Publication Date: 2006/11/01
Online ISSN: 1745-1361
DOI: 10.1093/ietisy/e89-d.11.2802
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Biological Engineering
Keyword: 
elbow joint,  isovelocity flexion movements,  electromyogram,  artificial neural network,  

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Summary: 
We investigated relations between torque and elbow joint angle for constant muscle activations in isovelocity flexion movements of the forearm in three normal subjects. The reference angular velocity was from 0 to 90°/s and the applied torque from 0 to 15% of maximum voluntary contraction. Integrated surface electromyograms (IEMGs) of six muscles, torque, angle and angular velocity of the elbow joint were measured. A mathematical model describing the relationship between these variables was constructed with an artificial neural network. We estimated elbow joint torque by presenting different elbow joint angles, constant IEMGs and constant angular velocity to the model. For elbow joint angles greater than 60°, the slope, which was defined as the rate of torque increase with respect to elbow joint angle, was negative. For elbow joint angles less than 50°, the slope changed from positive to negative when the angular velocity increased. This implied that the flexor muscle-elbow joint system could change from unstable to stable when the angular velocity increased.


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