Participants will receive the active Photobiomodulation

Participants will receive the placebo Photobiomodulation

Participants will receive the active Photobiomodulation

The ability to perform repeated sprints with changes of direction will be assessed using the Bangsbo sprint test (BST). The test consists of seven sprints of 34.2 meters between the starting cone (A) and the finishing cone (E), interspersed with a 25-second active recovery period. During recovery, participants perform a light jog back to the starting point (cone A). The change of direction (right or left) between cones B and C in the first sprint is determined by each participant's individual preference, and subsequent sprints are performed alternately between the right and left sides. Participants will be verbally encouraged to perform their best in all sprints. The following variables were analyzed: total time (sum of all sprints), and fatigue index (FI) = 100 - (average time/best time) x 100). The BST is considered valid and reliable for analyzing aerobic recovery capacity.

Aerobic recovery capacity in high-intensity intermittent running will be assessed using the yo-yo intermittent recovery test level 1 (YYIR1). The protocol consists of 40-meter runs (stages) between cones B and C (20 m out + 20 m back) followed by 10 seconds of active recovery between cones A and B (walking a 5 m path). The initial speed of the test is 10 km/h, with a progressive increase in speed by auditory stimulus (beeps) (the time between "beeps" decreases at each stage, forcing the athlete to run faster). The test is terminated when the participant does not reach the marking line (cone B) within the stipulated time in two attempts (even if not consecutive) or is unable to continue the test due to fatigue/exhaustion (6). Participants are verbally encouraged to perform as well as possible during the test. The total distance covered (in meters) will be used as a variable for aerobic performance. The YYIR1 test is considered valid and reliable for analyzing aerobic recovery capacity.

The RPE will be recorded immediately after the Bangsbo and YYIR1 tests, using the Borg 6-20 scale. The scale contains 15 points ranging from 6 "no effort" to 20 "maximum effort", and the participant indicate a number on the scale that represent their perceived exertion at that moment. RPE is a simple, valid and reliable instrument for assessing perceived exertion in running tests. All participants will be previously familiarized with the scale through the cognitive anchoring procedure.