Pre-exercise low-level laser therapy improves performance and levels of oxidative stress markers in mdx mice subjected to muscle fatigue by high-intensity exercise

This study was designed to determine if the levels of oxidative stress markers are influenced by low-level laser therapy (LLLT) in mdx mice subjected to high-intensity exercise training on an electric treadmill. We used 21 C57BL/10ScSn-Dmdmdx/J mice and 7 C57BL/10ScSn mice, all aged 4 weeks. The mice were divided into four groups: a positive control group of normal, wild-type mice (WT); a negative control group of untreated mdx mice; a group of mdx mice that underwent forced high-intensity exercise on a treadmill (mdx fatigue); and another group of mdx mice with the same characteristics that were treated with LLLT at a single point on the gastrocnemius muscle of the hind paw and underwent forced high-intensity exercise on a treadmill. The mdx mice treated with LLLT showed significantly lower levels of creatine kinase (CK) and oxidative stress than mdx mice that underwent forced high-intensity exercise on a treadmill. The activities of the antioxidant enzyme superoxide dismutase (SOD) were higher in control mdx mice than in WT mice. LLLT also significantly reduced the level of this marker. LLLT had a beneficial effect also on the skeletal muscle performance of mdx mice. However, the single application of LLLT and the dose parameters used in this study were not able to change the morphology of a dystrophic muscle.