Abstract
Objective: Cold therapy, so-called icing, is often used immediately after muscle injuries as first aid for the suppression of inflammation and pain relief. Recent evidences show icing retards the regeneration of injured skeletal muscle. On the other hand, microcurrent electrical neuromuscular stimulation (MENS) promotes the regeneration of injured skeletal muscle. In this study, we investigated the effects of the MENS with or without icing on the regeneration of injured skeletal muscle.
Methods: Eight-week-old male mice (C57BL/6J) were divided into 4 groups: control (C), cardiotoxin (CTX) injected (X), CTX injected with MENS (XM), and CTX injected with combined treatments with icing and MENS (XIM) groups. Necrosis-regeneration cycle was induced by an intramuscular injection of CTX into tibialis anterior (TA) muscles except for C group. After CTX–injection, the hindlimbs of the mice were soaked in ice-cold water (4ºC) for 20 minutes under anesthesia (XIM). After the treatments, both right and left hindlimbs of the mice in XIM and XM groups were treated with MENS (10 µA, 0.3 Hz, 250 msec) for 60 min a day and 3 days per week for 1 or 3 weeks. One and three weeks after CTX injection, TA muscles were dissected.
Results: MENS with or without icing facilitated the recovery of muscle protein content and muscle fiber morphology including mean fiber cross-sectional areas of injured TA muscle, compared with non-treated condition. These facilitating effects of MENS with or without icing were accompanied with the increase in the relative number of Pax7-positive nuclei, namely satellite cells. Judging from fiber morphology, MENS with icing had enhanced stimulating effects on the regeneration of injured skeletal muscle, compared with MENS-treated condition.
Conclusion: Evidence suggested that MENS with or without icing facilitated the regeneration of injured TA muscle. A combination treatment of MENS with icing might be a useful therapy for sports-related skeletal muscle injuries.
