Taiki Kodesho1, Keigo Taniguchi2, Takuya Kato1, Masaki Katayose3. 1. Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan. 2. Department of Physical Therapy, School of Health Sciences, Sapporo Medical University, West 17, South 1, Chuo-ku, Sapporo City, Japan. ktani@sapmed.ac.jp. 3. Department of Physical Therapy, School of Health Sciences, Sapporo Medical University, West 17, South 1, Chuo-ku, Sapporo City, Japan.
Abstract
PURPOSE: This study aimed to determine (1) intramuscular regional differences in the changes in the shear modulus of the rectus femoris (RF) muscle during passive knee flexion and (2) the relationship between shear modulus and passive knee extension torque. METHOD: The shear modulus maps as an index of muscle stiffness and the passive torque were obtained at seven regions during passive knee flexion at 2°/s within a knee joint range of motion of 0°-130° in 16 healthy males. RESULTS: The shear modulus of RF increased with the knee angle of flexion. The shear modulus of each longitudinal region was greater in the order of proximal, central, and distal region (p < 0.05). The relationship between the shear modulus and passive torque was highly fitted for all 16 subjects (p < 0.05). The mean coefficient of determination (R2) at second-order polynomial model per subject was 0.96 (± 0.03; range 0.61-0.99), and whole group was 0.58 (± 0.03; range 0.54-0.64) in all regions. CONCLUSIONS: The passive stiffness of RF was higher in the proximal region than in the other regions during passive knee flexion. Furthermore, the shear modulus-passive torque was related regardless of the measurement region within a muscle, and the results suggest that the passive knee extension torque reflects passive muscle stiffness of the RF.
PURPOSE: This study aimed to determine (1) intramuscular regional differences in the changes in the shear modulus of the rectus femoris (RF) muscle during passive knee flexion and (2) the relationship between shear modulus and passive knee extension torque. METHOD: The shear modulus maps as an index of muscle stiffness and the passive torque were obtained at seven regions during passive knee flexion at 2°/s within a knee joint range of motion of 0°-130° in 16 healthy males. RESULTS: The shear modulus of RF increased with the knee angle of flexion. The shear modulus of each longitudinal region was greater in the order of proximal, central, and distal region (p < 0.05). The relationship between the shear modulus and passive torque was highly fitted for all 16 subjects (p < 0.05). The mean coefficient of determination (R2) at second-order polynomial model per subject was 0.96 (± 0.03; range 0.61-0.99), and whole group was 0.58 (± 0.03; range 0.54-0.64) in all regions. CONCLUSIONS: The passive stiffness of RF was higher in the proximal region than in the other regions during passive knee flexion. Furthermore, the shear modulus-passive torque was related regardless of the measurement region within a muscle, and the results suggest that the passive knee extension torque reflects passive muscle stiffness of the RF.
Authors: Sandro R Freitas; André Antunes; Pierre Salmon; Bruno Mendes; Telmo Firmino; Carlos Cruz-Montecinos; Mauricio Cerda; João R Vaz Journal: J Biomech Date: 2018-11-17 Impact factor: 2.712