Infrared Low-level Laser Therapy Before Intense Progressive Running Test of High-level Soccer Players

To achieve the proposed objective it will perform a randomized, crossover triple-blinded, placebo-controlled trial, with high-level soccer players as volunteers. Twenty-two volunteers will be randomly allocated to two intervention groups: active or placebo PBMT before a progressive running test (ergospirometry test). The blood samples for biochemical analysis will be obtained before and after a progressive running test, and another outcomes (functional) will be obtained during the test. The data will be collected by a blind assessor. The statistical analysis will follow the intention-to-treat principles and data on functional analysis will be analyzed using the paired and two-tailed t-student test. Data on biochemical analysis will be analyzed using two-way ANOVA, followed by Bonferroni post hoc test. The investigators will analyze: functional aspects (rates of oxygen uptake -VO2max (absolute and relative), aerobic and anaerobic threshold and time until exhaustion), muscle damage (creatine-kinase -CK and lactate dehydrogenase -LDH), inflammatory markers (IL-1β, IL-6 and TNF-α) and oxidative stress markers (Thiobarbituric acid -TBARS, catalase - CAT, superoxidedismutase - SOD and carbonylated proteins).