Photobiomodulation in Different Doses on Strength Capacities and Functional Performance

Background: Photobiomodulation has been explored for years, with wide clinical use for wound healing and analgesia in varied orthopedic conditions, but the number of research and clinical use has increased during the last decade. Furthermore, considering the performance, the current literature is conflicting and restricted, with divergences in wavelength, power and energy density applied. Therefore, analyze different doses for a answer in short and long time, associated with capacities of strength, fatigue resistance and functional performance of handball players and healthy individuals becomes necessary. Objective: To analyze the effects of the application of LED photobiomodulation on the capacities of strength, functional efficiency, temperature and fatigue resistance of handball players and healthy individuals. Method: The study sample will be composed of 56 male individuals randomly allocated into four groups: LED 50J (G-50J), LED 240J (G-240J), LED 50-240J (G-50-240J) - progressive dose and Sham (G-S). The volunteers will be submitted to an evaluation of muscle performance and functional performance, metabolic, and physiological evaluation. After initial tests, in five consecutive weeks, the LEDT (940nm - infrared) will be applied to the quadriceps femoris muscle and hamstrings, bilaterally, associated with a muscle strength protocol. After 24 hours of the last application TLED, the tests will be repeated. Seven days after the last intervention will be performed a follow-up. For analysis, normality tests 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 volunteers will undergo pre-evaluation, 5 weeks of training associated with the LED application, being distributed in two applications per week, and a re-evaluation 24 hours after the last application, totaling a total of approximately 7 weeks. Thus, on the first day (Pre-test) volunteers will be submitted to anthropometric evaluation and evaluation by bioimpedance for analysis of detailed body composition. Then, the maximum voluntary contraction test (CVM) will be performed on the isokinetic dynamometer, together with the electromyographic evaluation. Before and after the evaluation with the isokinetic dynamometer, thermography will be collected. Still, will be evaluated the vertical jump test after 15 minutes of passive rest.

After the initial evaluations, the researcher will go apply the respective interventions, which consist of applying LEDs all over the quadriceps and hamstring bilaterally, while the sham group (GS) will receive the LED application off, without the emission of light. The application will occur for five weeks and will occur twice weekly, on days spaced for at least 48 hours. The same will be done in conjunction with the lower limb strength training protocol.

The tests performed at the time of pre-application of the LED (Pre-test) will be reapplied in the same order 24 hours after the last application of the interventions. After seven days of the last application, the isokinetic evaluation, electromyography, and vertical jump evaluation will be performed. In addition, at the end of the second and fourth weeks, the volunteer will carry out an evaluation with the isokinetic dynamometer, electromyography, plethysmography, and thermography.

Eligibility Criteria:
Inclusion Criteria:

* Handball players with the participation of at least one official match in the last year and attend 70% of the team's activities during the current season; or
* Healthy individuals;

Exclusion Criteria:

* musculoskeletal injury in the last three months;
* cardiovascular diseases;
* use of anabolic, anti-inflammatory and analgesic drugs 72 hours before the evaluations;
* use of alcohol and illicit drugs during the collection period;