Electrical Characteristics of Physiological Response in Calf Muscle Compartments to Locomotor Training; 人类小腿肌肉对运动训练生理响应的电学特性研究

Objective Locomotor training has been shown to preferentially affect muscle function in many chronic diseases which has been used in the treatment of sarcopenia. In this study, we propose electrical impedance tomography (EIT) to study the electrical characteristics of physiological response in calf muscle compartments induced by locomotor training, which is intended to visualize the effectiveness of locomotor training on the increase in volume of calf muscle fibers. Methods Experimental subjects were asked to perform unilateral heel rises on the right and left legs on 5 consecutive experimental days. EIT was applied to detect the conductivity distribution of calf muscles after locomotor training. In order to quantify the effectiveness of locomotor training, a paired sample t-test was used to analyze the spatial-mean conductivity <σ> from reconstructed EIT images. Results The results show that the spatial-mean conductivity <σ>M1 of M1 compartment (which is recognized as the position of the gastrocnemius muscle) is significantly increased in post-training by locomotor training. In addition, the spatial-mean conductivity in pre-training <σpre>M1 shows an increasing tendency in EIT measurement results on 5 consecutive experimental days. The lean mass of all subjects in pre- and post-training parts which was performed in the morning of experimental day 1 is linearly related to <σ>M1; the increase in <σ>M1 and spatial-mean conductivity difference ratio Δ<σ>M1 between pre- and post-training followed the same tendency as extracellular water/intracellular water (ECW/ICW) τ by ECW/ICW difference ratio Δτ. Conclusion Since conductivity is sensitive to changes in extracellular volume which correlates with sarcoplasmic hypertrophy. The < σpre>M1 tended to increase during 5 consecutive experimental days of EIT measurements, which implies an increase in muscle fiber volume with sarcoplasmic hypertrophy occurring. Therefore, EIT is able to effectively detect the effectiveness of locomotor training to increase the volume of human calf muscle fibers. © 2023 Institute of Biophysics,Chinese Academy of Sciences. All rights reserved.