A method for estimating torque-vector directions of shoulder muscles using surface EMGs.
In this study, a new method is proposed to estimate the torque-vector directions of each shoulder muscle. The method is based on a multiple regression model that reconstructs shoulder torque, which is calculated from the hand force and posture, from the surface EMG of many muscles recorded simultaneously. The torque-vector directions of eleven shoulder muscles of four subjects were obtained at up to 30 different arm postures with this method. The mean confidence interval ( p< 0.05) of the estimated torque-vector direction of each subject was 7.7-10.6 degrees. The correlation coefficient between the measured shoulder torque and reconstructed shoulder torque was between 0.76-0.84. The results for majority of the muscles were in accordance with previous studies, and reasonable from the viewpoint of anatomy. The torque-vector directions of a muscle, which are estimated with this method, have more of a functional meaning than a pure anatomical or mechanical one. These indicate the direction of the shoulder torque accompanying the muscle activation for a normal shoulder action that involves the cooperative contraction of many muscles.
Yoshida
Naoki
N
College of Medical Technology, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan. yoshida@1994.jukuin.keio.ac.jp
Domen
Kazuhisa
K
Koike
Yasuharu
Y
Kawato
Mitsuo
M
D000328:Adult; D004576:Electromyography / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D008954:Models, Biological; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology; D015203:Reproducibility of Results; D012785:Shoulder Joint / Q000502:physiology*; D019415:Torque