Protective effects of early low-intensity exercise on the antigravity soleus muscle following focal cerebral infarction in rats

Abstract

Background Skeletal muscle changes following stroke are a major factor influencing subsequent motor recovery. Objective To examine the effects of early low-intensity exercise on motor function, neurological deficits, soleus muscle mass, fiber-type composition, and muscle fiber cross-sectional area following experimental stroke. Methods Adult male Wistar rats were randomly assigned to ischemia-control (IC; n = 23) and ischemia-exercise (IE; n = 23) groups. Stroke was induced 90 min after occlusion of the left middle cerebral artery. The next day, the rats ran on a treadmill for 20 min once a day for up to 28 days. The beam-walking test and a neurological evaluation scale were used to assess post-ischemia functional recovery. The muscle fiber characteristics of the soleus of both sides were examined using histochemical and morphometric methods at 1, 3, 5, 7, 14, and 28 days post-stroke. Results Compared to that in the IC group, the motor recovery and neurological function on day 28 were significantly greater in the IE group. The infarct volumes were initially comparable; however, the IE group exhibited a significant reduction beginning on day 5, and two-way ANOVA confirmed smaller infarct volumes in the IE group overall. The soleus muscle weight, fiber-type distribution, and cross-sectional area showed no significant temporal or between-group differences. Conclusions Early exercise intervention promotes functional recovery and may attenuate lesion progression as assessed by TTC staining without detectable deterioration of soleus muscle morphology, highlighting the potential value of safe early mobilization after stroke.