The effect of middle frequency electrical stimulation combined with eccentric contraction on disuse atrophy in deep portion of calf muscles

Abstract

The purpose of the present study was to investigate the combined effect of electrical stimulation (ES) and eccentric contraction to prevent disuse atrophy in rat deep portion of calf muscles. Rats were randomly divided into the control, hindlimb unloading for 2 weeks (HU), and HU plus ES combined concentric (HU+cES), isometric (HU+iES), eccentric (HU+eES) contraction groups. The animals in the ES groups were stimulated electrically using middle frequency current twice a day during the unloading period. Animals undergoing HU for 2 weeks exhibited the significant loss of muscle mass, decreased cross-sectional area of muscle fibers, and increased expression of ubiquitinated proteins in the soleus muscles compared with the control animals. HU+eES inhibited the loss of muscle mass, decreased cross-sectional area of muscle fibers in the soleus muscles. In addition, the HU+eES inhibited the HU-induced increase in ubiquitinated protein expression in the soleus muscles. Furthermore, the HU+eES inhibited the loss of muscle mass, decreased cross-sectional area of muscle fibers in the soleus muscles, and the increase in ubiquitinated protein expression in the soleus muscles compared with ES combined using other types of contraction groups. Our previous study showed middle frequency current could contract in the deep muscle of hindlimbs. Additionally, eccentric contraction caused larger generated tension in muscle fibers than other types of contraction. The combination of electrical stimulation with eccentric contraction might cause higher preventive effects on muscle atrophy in the deep portion of calf muscle.