Local and Systemic Effects of Photobiomodulation Therapy on Muscle Performance and Recovery Post-exercise.

Recent studies with photobiomodulation therapy have shown positive results in delaying skeletal muscle fatigue and improving performance through levels of biochemical markers and variables related to exercise when this therapy was applied before exercise. Some studies suggest that photobiomodulation therapy has systemic effects, but it is not known whether therapy exerts any systemic effects on human skeletal muscle. With this factor in mind, this research aims to verify the local and systemic effects of phototherapy on muscle performance and recovery after exercise in healthy male participants. This research consists in a randomized, triple-blinded, placebo-controlled trial, with participation of 30 healthy subjects. Will be analyzed parameters related to exercise performance (peak torque in the maximum voluntary contraction test- MVC), delayed onset muscle soreness (DOMS) by visual analogue scale (VAS), and biochemical marker of muscle damage (CK) and blood Lactate (BL). The analysis will be performed before exercise protocol (baseline), after 1 minute of the exercise, and 1, 24, 48 and 72 hours after the end of exercise protocol

A total of 30 healthy male non-athletes, between 18-35 years, will be randomly divided into 3 experimental groups, named "Placebo (Control)", "Local", "Systemic", according to the lower limb who will receive photobiomodulation therapy. Firstly, a blood collection will be performed by a nurse with sterile and disposable materials for posterior analysis of creatine kinase (CK) and Blood Lactate (BL). Delayed onset muscle soreness (DOMS) will be assessed with the Visual Analogue Scale (VAS) using a 10 cm line. Participants will be instructed to mark the line where their pain best fits at that time (0=no pain, 10=worst pain).Then, the maximum voluntary contraction test (MVC) will be performed, which will consist in performing 3 times of 5-sec isometric contractions of the non-dominant knee extensors in the isokinetic dynamometer device. During the execution of the MVC, the participants will be verbally encouraged to exert the greatest force at that moment. Photobiomodulation therapy will be applied 2 minutes after the MVC test in six points of non-dominant anterior thigh muscle. After irradiation, participants will perform the protocol of eccentric contractions. This protocol will be performed to induce muscle fatigue by resisting the movement of knee flexion in 5 series of 15 repetitions with 30 seconds -intervals (eccentric contractions). Assessments (blood collection, VAS and MVC) will be performed before warm-up (baseline), 1 minute after exercise protocol and 1, 24, 48 and 72 hours after eccentric exercise protocol.

Eligibility Criteria:
Inclusion Criteria:

* Healthy individuals,
* Non-athletes
* Those who practice physical activity at maximal of once a week
* Between 18 and 35 years old,
* Male
* No history of musculoskeletal injury in the hip or knee previous two months of the study.
* Not be taking pharmacological agents and / or nutritional supplements, and should have frequency of 100% in all days of data collection.

Exclusion Criteria:

* Individuals who present musculoskeletal injury during the study
* Chronic joint disease in the non-dominant lower limb