Low Level Laser Therapy in Muscle Fatigue and Muscle Recovery

Low Level Laser Therapy in Muscle Fatigue and Muscle Recovery After Exercise: What is the Ideal Dose?

Muscle fatigue and muscle recovery after exercise are recent areas of research involving Low Level Laser Therapy (LLLT) and many factors remain unknown, such as optimal doses, power and application parameters, mechanisms of action, effects on long-term exercise and the long-term effects on skeletal muscle recovery.

The present research project aims to assess the effects of long-term recovery of LLLT in skeletal muscle after exercise and identify the optimal dose application of LLLT.

After defining the best dose of application, we recruited two groups which will be irradiated with different power, 100mW and 400mW in order to seek the optimal parameter of low level laser therapy in performance.

The investigators believed that the Low Level Laser Therapy can delay the physiological process of muscle fatigue, reduce injury or skeletal muscle microdamage arising from physical effort and accelerate muscle recovery after exercise.

To achieve the proposed objectives it was performed a randomized, double-blinded, placebo-controlled trial, with voluntary participation of high-level soccer athletes.

Participants received an application of low level laser prior to execution of a strenuous exercise. It was used a laser with a cluster of 5 diodes (810 nm, 200 mW each diode) with different doses (placebo, 2J, 6J, 10J) and power of 200mW.

In a second step, with the optimal dose already defined, this was used to be applied with different powers in two experimental groups, 100mW and 400mW.

The investigators analysed parameters related to volunteers exercise performance (torque peak / maximum voluntary contraction), delayed onset muscle soreness, and biochemical markers of muscle damage (CK and LDH), inflammation (interleukin 1 and 6, alpha tumoral necrosis factor) and oxidative stress (TBARS, CAT, SOD and carbonylated proteins). The analysis was performed before exercise protocols, after 1 minute, and 1, 24, 48, 72 and 96 hours after the end of exercise protocol in both parts of the study.

Inclusion Criteria:

• professional soccer players aged between 18 and 35 years old;
• not presenting historical musculoskeletal injury in regions of the hip and knee in the 2 months preceding the study;
• not making use of pharmacological agents and/or nutritional supplements;
• participating with minimum frequency of 80% of the training team

Exclusion Criteria:

• athletes who experience musculoskeletal injury during the study;
• athletes who for whatever reason have their training routine changed with respect to the rest of the team during the course of study.