Wang Ruoli, Zhang Longbin, Jalo Hoor, Tarassova Olga, Pennati Gaia Valentina, Arndt Anton
KTH MoveAbility Lab, Department of Engineering Mechanics, KTH Royal Institute of Technology, Stockholm, Sweden.
Biomechanics and Motor Control Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden.
Front Bioeng Biotechnol. 2024 Nov 26;12:1453604. doi: 10.3389/fbioe.2024.1453604. eCollection 2024.
This study was to investigate alterations in contractile properties of the ankle plantar- and dorsiflexors in post-stroke individuals. The correlation between muscle architecture parameters and contractile properties was also evaluated.
Eight post-stroke individuals and eight age-matched healthy subjects participated in the study. Participants were instructed to perform maximal isometric contraction (MVC) of ankle plantar- and dorsiflexors at four ankle angles, and isokinetic concentric contraction at two angular velocities. B-mode ultrasound images of gastrocnemius medialis (GM) and tibialis anterior (TA) were collected simultaneously during the MVC and isokinetic measurements. Individualized torque-angle and torque-angular velocity relations were established by fitting the experimental data using a second-order polynomial and a rectangular hyperbola function, respectively. Muscle structure parameters, such as fascicle length, muscle thickness and pennation angle of the GM and TA muscles were quantified.
Post-stroke subjects had significantly smaller ankle plantarflexor and dorsiflexor torques. The muscle structure parameters also showed a significant change in the stroke group, but no significant difference was observed in the TA muscle. A narrowed parabolic shape of the ankle PF torque-fiber length profile with a lower width span was also found in the stroke group.
This study showed that the contractile properties and architecture of ankle muscles in post-stroke individuals undergo considerable changes that may directly contribute to muscle weakness, decreased range of motion, and impaired motion function in individuals after stroke.
本研究旨在调查中风后个体踝关节跖屈肌和背屈肌收缩特性的变化。同时评估肌肉结构参数与收缩特性之间的相关性。
八名中风后个体和八名年龄匹配的健康受试者参与了本研究。受试者被要求在四个踝关节角度进行踝关节跖屈肌和背屈肌的最大等长收缩（MVC），并在两个角速度下进行等速向心收缩。在MVC和等速测量过程中，同时采集内侧腓肠肌（GM）和胫骨前肌（TA）的B型超声图像。分别使用二阶多项式和矩形双曲线函数拟合实验数据，建立个体化的扭矩-角度和扭矩-角速度关系。量化GM和TA肌肉的肌束长度、肌肉厚度和羽状角等肌肉结构参数。
中风后受试者的踝关节跖屈肌和背屈肌扭矩明显较小。中风组的肌肉结构参数也有显著变化，但TA肌肉未观察到显著差异。中风组还发现踝关节跖屈扭矩-纤维长度曲线呈变窄的抛物线形状，宽度跨度较小。
本研究表明，中风后个体踝关节肌肉的收缩特性和结构发生了相当大的变化，这可能直接导致中风后个体的肌肉无力、运动范围减小和运动功能受损。
