Effects of Photobiomodulation Therapy in Strength Training and Detraining in Humans

Study Overview
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Brief Summary
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In last years it has been demonstrated that photobiomodulation therapy (PBMT) has ergogenic effects, improving muscular performance and accelerating post-exercise recovery. However, many aspects related to these effects and its' clinical applicability remain unknown. Therefore, the aim of this project is to evaluate the ergogenic effects of PBMT in detraining after a strength training protocol.

Detailed Description
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It will be carried out a randomized, triple-blind, placebo-controlled trial. Forty-eight volunteers will be randomly allocated to four experimental groups: PBMT before the strength training sessions and PBMT during the detraining period; PBMT before the strength training sessions and placebo during the detraining period; Placebo before the strength training sessions and PBMT during the detraining period; Placebo before the strength training sessions and placebo during the detraining period . The individuals randomly allocated to the different groups will be subjected to 12 consecutive weeks of dynamic strength training involving leg-press and knee extension exercises in leg-press and leg-extension machines, respectively, 2 times a week.After the 12-week training period, the volunteers will receive the application of PBMT or placebo depending on the group to which they are allocated for 4 weeks (2 times a week) without training. The data will be collected by a blind assessor. It will be analyzed the muscular strength and the structural properties of quadriceps before starting the study (baseline), at 4, 8, and 12 weeks after starting the training period, and at 4 weeks after completing the training (detraining period), in both lower limbs. The findings will be tested for their normality using the Shapiro-Wilk test. Parametric data will be expressed as mean and standard deviation and non-parametric data as median and respective upper and lower limits. Parametric data will be analyzed by two-way repeated measures analysis of variance (ANOVA; time versus experimental group) with post-hoc Bonferroni correction. Non-parametric data will be analyzed using the Friedman test and, secondarily, the Wilcoxon signed-rank test. Data will be analyzed in terms of both their absolute values and their relationship to the percentage change based on the values established in the baseline tests. The significance level will be set at p<0.05.

Official Title
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Effects of Photobiomodulation Therapy in Strength Training and Detraining in Humans

Conditions
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Muscle Strength

Intervention / Treatment
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* Device: PBMT
* Device: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy men; Aged from 18 to 35 years; Complete at least 80% of the study procedures will be included in the study. Exclusion Criteria: History of musculoskeletal injury in the hip and knee regions in the 2 months before the study; Become injured during the study; Regularly use pharmacological agents and/ or nutritional supplements; Signs and symptoms of any neurological, metabolic, inflammatory, pulmonary, oncological, or cardiovascular disease that may limit the execution of high-intensity exercises.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: PBMT + training/ PBMT + detraining<br>PBMT applied before the strength training sessions (12 weeks, 2 times a week) and PBMT applied during the detraining period (4 weeks, 2 times a week). | Device: PBMT<br>* PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). A 12-diode cluster, with 4 905-nm laser diodes (12.5W peak power for each diode), 4 875-nm LED diodes (17.5 mW mean power for each diode), and 4 640-nm LED diodes (15 mW mean power for each diode), manufactured by Multi Radiance Medical® (Solon, OH, USA), will be used to apply the PBMT. The dose used for applications during the training and/or detraining periods will be 30 Joules (J) per site (180 J per thigh). PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>|
| Experimental: PBMT + training/ placebo + detraining<br>PBMT applied before the strength training sessions (12 weeks, 2 times a week) and placebo applied during the detraining period (4 weeks, 2 times a week). | Device: PBMT<br>* PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). A 12-diode cluster, with 4 905-nm laser diodes (12.5W peak power for each diode), 4 875-nm LED diodes (17.5 mW mean power for each diode), and 4 640-nm LED diodes (15 mW mean power for each diode), manufactured by Multi Radiance Medical® (Solon, OH, USA), will be used to apply the PBMT. The dose used for applications during the training and/or detraining periods will be 30 Joules (J) per site (180 J per thigh). PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>Device: Placebo<br>* Placebo PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). The placebo PBMT will per performed using the dose of 0 J per diode. The sounds and signals emitted from the device as well as the information displayed on the screen will be identical, regardless of the type of treatment (active or placebo). Placebo PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>|
| Experimental: Placebo + training/ PBMT + detraining<br>Placebo applied before the strength training sessions (12 weeks, 2 times a week) and PBMT applied during the detraining period (4 weeks, 2 times a week). | Device: PBMT<br>* PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). A 12-diode cluster, with 4 905-nm laser diodes (12.5W peak power for each diode), 4 875-nm LED diodes (17.5 mW mean power for each diode), and 4 640-nm LED diodes (15 mW mean power for each diode), manufactured by Multi Radiance Medical® (Solon, OH, USA), will be used to apply the PBMT. The dose used for applications during the training and/or detraining periods will be 30 Joules (J) per site (180 J per thigh). PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>Device: Placebo<br>* Placebo PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). The placebo PBMT will per performed using the dose of 0 J per diode. The sounds and signals emitted from the device as well as the information displayed on the screen will be identical, regardless of the type of treatment (active or placebo). Placebo PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>|
| Placebo Comparator: Placebo + training/ placebo + detraining<br>Placebo applied before the strength training sessions (12 weeks, 2 times a week) and placebo applied during the detraining period (4 weeks, 2 times a week). | Device: Placebo<br>* Placebo PBMT will be applied bilaterally using the direct contact method with light pressure on the skin to 6 sites of the anterior thigh (2 medial, 2 lateral, and 2 central). The placebo PBMT will per performed using the dose of 0 J per diode. The sounds and signals emitted from the device as well as the information displayed on the screen will be identical, regardless of the type of treatment (active or placebo). Placebo PBMT will be applied before each workout and during the detraining period, depending on the group to which the volunteers are allocated.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak Torque | The peak torque will be measured by Maximum Voluntary Contraction (MVC) test. | 16 weeks - 4 weeks after completing the training (detraining period). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak Torque | The peak torque will be measured by Maximum Voluntary Contraction (MVC) test. | 4, 8, and 12 weeks after starting the training period. | 
| Muscle strength | Muscle strength will be measured by one-repetition maximum (1-RM) test. | 4, 8, and 12 weeks after starting the training period, and at 4 weeks after completing the training (detraining period). | 
| Muscle thickness | Muscle thickness will be measured by ultrasound imaging. | 4, 8, and 12 weeks after starting the training period, and at 4 weeks after completing the training (detraining period). | 
| Muscle fascicle length | Muscle fascicle length will be measured by ultrasound imaging. | 4, 8, and 12 weeks after starting the training period, and at 4 weeks after completing the training (detraining period). | 
| Muscle fiber pennation angle | Muscle fiber pennation angle will be measured by ultrasound imaging. | 4, 8, and 12 weeks after starting the training period, and at 4 weeks after completing the training (detraining period). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Photobiomodulation Therapy, Low-level Laser Therapy, Skeletal Muscle Strenght, Strength Training