Effect of Light-emitting Diode (LED) Photobiomodulation Therapy on Muscular Fatigue in University Handball Athletes

Overview

Introduction: Low-intensity laser therapy (LBI) is a therapeutic modality with a large number of clinical studies in recent years, taking into account its effectiveness in tissue repair, pain control and, more recently, to increase performance. It is known that LED therapy has immediate effects. Therefore, analyzing the TLED in the infrared spectrum for acute responses at different times along with fatigue resistance capabilities, heart rate variability and biochemical response to fatigue in handball athletes becomes necessary. Objective: To analyze the acute effects of LED phototherapy (940nm) on fatigue resistance and recovery after strenuous exercises of university athletes. Method: The study sample will consist of 32 and 36 male athletes, for biceps brachii and quadriceps femoris, respectively. The athletes will be randomly assigned into four groups: Immediate TLED (TLED-I), TLED 15Min (TLED-15), Immediate Sham (Sham-I) and Sham 15Min (Sham-15). The tests performed will involve bioimpedance evaluation, blood lactate, electromyographic analysis and evaluation of maximum voluntary contraction by means of the maximal repetition test (1RM). Thus, the TLED will be applied on the muscle group to be evaluated, unilaterally, the same tests being repeated in the sequence. For analysis of the data, normality test will be used to verify the distribution and adequate statistical tests for the appropriate intra and intergroup comparisons, being considered two factors in the comparisons, time and group. A significance level of 5% will be adopted.

It is a blinded randomized clinical trial. The athletes will undergo a previous evaluation (day 1) comprised by anamnesis and evaluation of the bioimpedance to analyze the body composition, will still carry out the evaluation of the load for a maximum repetition. Thus, 7 days after (day 2) the previous evaluation in the times immediately after and after 15 minutes of the LED application will be carried out new tests. These will involve assessment of blood lactate, heart rate variability and electromyography. In addition, during the execution of the fatigue protocol will be collected the number of repetitions of muscle contraction and its total execution time. Due to the number of athletes that make up the university team (n = 19), cross-over will be necessary, where all athletes will initially be distributed to the 04 pre-defined groups in each subproject, and after the 7 days, they will be divided again.