Tissue Mechanisms

<strong>5.1 Muscles</strong> Previous chapters mentioned the positive results of LLLT in muscle recovery, as reported by Ferraresi et al. The authors concluded that it takes 3 - 6 h for the LLLT to exert the maximum effect on the muscle physiology, consisting of increased matrix metalloproteinase activity and ATP synthesis. This effect could still be observed 24 h after the laser irradiation. Rochkind and co-workers have also worked with LLLT applied to muscles, investigating the influence of low-power laser irradiation on creatine kinase (CK) and the amount of acetylcholine receptors (AChRs) present in intact gastrocnemius muscle <i>in vivo</i>, as well as the synthesis of DNA and of CK in muscle cells <i>in vitro</i>. The authors found that LLLT significantly increased CK activity and AChR levels in one and two months, when compared to control animals. The biochemical changes on muscle cells might be due to a trophic signal for increased activity of CK, which leads to a preservation of a reservoir of high-energy phosphate that is available for rapid ATP synthesis.