Background/Aim: While growing evidence supports the use of photobiomodulation therapy (PBMT) for performance and recovery enhancement, there have only been laboratory-controlled studies. Therefore, the aim of this study was to analyze the effects of PBMT in performance and recovery of high-level rugby players during an anaerobic field test.

Methods: It is a randomized, crossover, double-blinded, placebo-controlled trial. Twelve male high-level rugby athletes were recruited in this study. No intervention was performed before the Bangsbo Sprint Test (BST) at familiarization phase (week 1). At weeks 2 and 3, pre-exercise PBMT or placebo were randomly applied to each athlete. PBMT/placebo irradiation was performed at 17 sites of each lower limb, employing a cluster with 12 diodes (4 laser diodes of 905nm, 4 LED diodes of 875nm, and 4 LED diodes of 640nm, 30J per site - manufactured by Multi Radiance Medical™). Average time of sprints, best time of sprints, and fatigue index were obtained from BST. Blood lactate levels were assessed at baseline, and at 3, 10, 30 and 60 minutes after BST. Athletes' perceived fatigue was also assessed through a questionnaire.

All exercise tests were conducted in an enclosed soccer/rugby field. The three test phases, administered one week apart, were performed on the same day of the week (Tuesday) and time (1-5pm). The average temperature inside the building during the trials ranged from 26°C to 28°C. At first stage (exercise test 1) all athletes performed the Bangsbo Sprint Test (BST) to familiarization with the procedure. No interventions or comparators were applied before this test. However, at the second and third stages (exercise tests 2 and 3, respectively) either a placebo or active PBMT was applied according to randomization. Blood samples were collected from the athlete's fingertips prior to stretching and warming-up (baseline), and at 3, 10, 30 and 60 minutes after BST at each of the three study stages/phase (exercise tests). After blood sample collection (to establish baseline), a warm-up comprised of low-intensity activities such as dynamic stretches and low-intensity short running were performed by each athlete. Following the warm-up and cool down period, either the active or placebo comparator was applied to the athlete according to the randomization procedure for the second test. For the third test, the other comparator was utilized to complete the cross over design. A quick perception of fatigue survey was administered following each test.

Inclusion Criteria:

• high-level athletes from São José Rugby Club (Brazil)

Exclusion Criteria:

• Athlete would be excluded if the participant presented any skeletal muscle injury
• if athlete took any nutritional supplement or pharmacological agent
• if the athlete presented signs and symptoms of any disease (i.e., neurological, inflammatory, pulmonary, metabolic, oncologic), and
• if the athlete had history of cardiac arrest that could limit performance of high-intensity exercises

all data is properly stored in electronic devices and available for possible doubts regarding to methodological procedures or results.