Comparison of the Effects of Cryotherapy and Thermotherapy on Permeability After Skeletal Muscle Injury

Skeletal muscle injuries are common in active individuals. The inflammatory process is a vital component of muscle healing beginning with enhanced permeability. As blood vessels dilate and capillaries become more permeable, inflammatory promoting proteins and white blood cells enter the damaged area to eliminate debris and initiate regeneration. The application of controlled temperature on the injured muscle remains the most common treatment. However, there is conflicting evidence on the advantages of cryotherapy, and there is a lack of evidence on benefits of thermotherapy. Therefore the purpose of our study was to compare the effects of cryotherapy and thermotherapy on muscle vascular permeability in both male and female mice. Barium chloride (BaCl2) was injected into the right tibialis anterior (TA) to cause a chemical injury and sodium chloride (NaCl) was injected into the left TA as a control. Therapy was started immediately after injury. The control group was anesthetized, the thermotherapy group received heat treatment (41°C) while anesthetized, and the cryotherapy group received cold therapy (10°C) while anesthetized, for 20 mins every 3 hours, during 2 consecutive 12 hr wake cycles. Evans blue (EB) dye was injected through the lateral tail vein to assess vascular permeability in the TA muscles. There was no significant difference in permeability between the NaCl injected muscles in the cryotherapy group vs. control regardless of sex. Thermotherapy significantly enhanced permeability in NaCl injected muscles vs. control in males (1.05+0.45 vs. 4.47+0.99) Permeability was significantly elevated in the BaCl2 injected TA muscles in all groups except for male thermotherapy NaCl vs. BaCl2 injected muscles and female cryotherapy NaCl vs. BaCl2. To compare sex differences, we compared thermotherapy and cryotherapy treatment differences as a fold change versus no treatment. There was no difference between cryotherapy treatment on injured muscles in males and females. Thermotherapy significantly enhanced permeability above BaCl2 injury in females, but not males, respectively (1.71+0.19 vs. 0.9788+0.097). Our future plans are to determine whether these permeability sex differences in temperature treatment translate to differences in the healing progression of muscle, or the force the muscle is capable of producing