Low-level laser therapy on skeletal muscle inflammation: evaluation of irradiation parameters

Abstract

We evaluated the effect of different irradiation parameters in low-level laser therapy (LLLT) for treating inflammation induced in the gastrocnemius muscle of rats through cytokines concentration in systemic blood and analysis of muscle tissue. We used continuous (830 and 980 nm) and pulsed illuminations (830 nm). Animals were divided into five groups per wavelength (10, 20, 30, 40, and 50 mW), and a control group. LLLT was applied during 5 days with a constant irradiation time and area. TNF-α, IL-1β, IL-2, and IL-6 cytokines were quantified by ELISA. Inflammatory cells were counted using microscopy. Identical methodology was used with pulsed illumination. Average power (40 mW) and duty cycle were kept constant (80%) at five frequencies (5, 25, 50, 100, and 200 Hz). For continuous irradiation, treatment effects occurred for all doses, with a reduction of TNF-α, IL-1β, and IL-6 cytokines and inflammatory cells. Continuous irradiation at 830 nm was more effective, a result explained by the action spectrum of cytochrome c oxidase (CCO). Best results were obtained for 40 mW, with data suggesting a biphasic dose response. Pulsed wave irradiation was only effective for higher frequencies, a result that might be related to the rate constants of the CCO internal electron transfer process.

Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness

“…6,38,39 Likewise, gene expression of MSTN, a gene marker of muscle wasting and weakness, 33 was also decreased with LEDT applied after the training program, suggesting an important reduction in the signaling seen in muscle atrophy. 20,21 Genes related to a marker of cell proliferation and protein synthesis (mTOR) 34 and oxidative stress defense (SOD2) 35 were also increased by LEDT, confirming the molecular effects of phototherapy 39 in humans.…”

Low-level laser therapy (LLLT) accelerates the sternomastoid muscle regeneration process after myonecrosis due to bupivacaine

“…Macedo et al [74] studying dystrophic muscle cells verified that LLLT treatment reduced the TNF-α and NF-κB levels. Mantineo et al [75] utilized LLLT at five frequencies (5, 25, 50, 100, and 200 Hz) for treating inflammation induced in the gastrocnemius muscle and the treatment effects occurred for all doses with a reduction of TNF-α, IL-1β, IL-6 cytokines and inflammatory cells.…”

“…Laser therapy (LT) has been reported to play a positive role in muscle regeneration. LT acts as an analgesic, stimulating the proliferation of muscle and satellite cells, enhancing protein synthesis in myoblasts and increasing the area of muscle fibers and mitochondrial density [35][36][37][38][39][40][41][42]. Laser irradiation also acts as an adjunctive therapy in neuronal injury [43] and chronic pain relief [44][45].…”

Investigation of the Comparative Effects of Red and Infrared Laser Therapy on Skeletal Muscle Repair in Diabetic Rats

“…Furthermore, the infrared laser produced a significant decrease in the injured area and higher MyoD and myogenin It is of common knowledge that DM leads to alterations in the musculoskeletal system, such as muscle atrophy, decreased skeletal muscle strength, ischemia, and impaired muscle growth and regeneration after an injury. 22,24 Moreover, LLLT may have induced the activation of myogenic satellite cells and promotion angiogenesis, contributing to the acceleration of the muscle repair. 18,24,25 The histological findings of the present study corroborate those statements and showed that both laser wavelengths used induced a reduction of the muscle destroyed zones and a modulation of the inflammatory process in the area of the lesion.…”