Mechanical property analysis of the gastrocnemius muscle of rats immobilized and submitted to the Russian current

Abstract

Neuromuscular electric stimulation by Russian current, used in rehabilitation, is able to increase muscle trophism and strength, especially in muscles with post-immobilization deficit, as is the case of injuries during sports practice. The purpose here was to assess the gastrocnemius muscle mechanical properties of rats immobilized for 14 days and subjected to electric stimulation by Russian current for 10 days. Thirty two Wistar female rats were divided into four groups: control (G1), immobilized (G2), immobilized and freed (G3), and immobilized and afterwards submitted to Russian current (G4). Mechanical properties - maximum load and stretch, stiffness, and resilience - were assessed by longitudinal traction. As to maximum load, G4 showed higher values when compared to the only-immobilized group (G2, p<0.001), though not attaining G1 values. In the analysis of maximum elongation results, G3 and G4 presented significantly higher values than G2 (p<0.001). Concerning stiffness, only G2 reached higher values (p<0.05) than G1. As to resilience, G4 presented significantly lower values than G1 (p<0.05), but still higher than G2's (p<0.001). Hence the study showed that Russian current, applied for 10 days after a 14-day immobilization, is beneficial, though not able to restore all the muscle mechanical properties at control level.