Low level laser therapy on injured rat muscle: assessment of irradiation parameters

Abstract

Although studies show the clinical effectiveness of low level laser therapy (LLLT) in facilitating the muscle healing process, scientific evidence is still required to prove the effectiveness of LLLT and to clarify the cellular and molecular mechanisms triggered by irradiation. Here we evaluate the effect of different LLLT wavelengths, using continuous coherent Laser illumination (830 nm and 980 nm) and non-coherent LED illumination (850 nm), in the treatment of inflammation induced in the gastrocnemius muscle of Wistar rats, through the quantification of cytokines in systemic blood. We verified that all applied doses of coherent radiation produce an effect on reducing the concentration of pro-inflammatory TNF-α and IL-1β cytokines, while no treatment effect was observed after irradiation with non-coherent radiation. The best results were obtained for 40 mW at 830 nm. The results may suggest an important role of coherence properties of laser in LLLT.