Photobiomodulation (PBM) Therapy on Muscle Performance in Elderly Women

Study Overview
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Brief Summary
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The present project aims to investigate the acute and chronic effects of laser photobiomodulation (PBM) at 808 nm on muscle performance in physically active elderly women. The hypothesis of this study is that laser PBM would improve muscle strength (i.e., MVIC and 1RM) and endurance (i.e., repetitions-to-failure, blood lactate levels), functional capacity (i.e., short physical performance battery score), and rating of perceived exertion when compared with placebo laser.

Detailed Description
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The purpose of this study will be to investigate the acute and chronic effects of laser PBM (λ: 808 nm) on muscle performance in physically active elderly women. For this purpose, the participants will be enrolled in two trials: Trial 1: Initially, all participants (n = 20/group) will be submitted for a 1-wk familiarization period (3 non-consecutive sessions) of functional tests (i.e., standing balance, gait speed, and chair stand tests) from short physical performance battery (SPPB), knee flexion-extension exercise (3 sets of 10-12 repetitions), maximum voluntary isometric contraction (MVIC), balance test on a force platform, and one-repetition maximum (1RM) test for knee extension exercise. Thereafter, participants will be randomized to receive 1 of 2 treatments (active or placebo laser) on two occasions (T1 and T2), separated by a 7-day washout period. During T1 and T2, participants will receive their respective treatments and then perform the muscle performance tests, separated by 10 minutes, in the following order: SPPB, MVIC, and repetitions-to-failure. After the last test, the participants will be instructed to reported the perceived exertion by OMNI scale, and a blood sample will be collected for measurement of blood lactate levels. Differences between groups will be assessed using a 2-tailed paired t-test. The significance level will be 0.05. Trial 2: participants will be randomized into two groups (n = 20/group): active laser or placebo laser. Both groups will be submitted for a 10-wk resistance training program (2 x/week) involving unilateral knee extension exercise. The following variables will be assessed from pre-to post-training: anthropometric, muscle thickness from vastus lateralis muscle using ultrasound, MVIC, 1RM, repetition-to-failure, and balance variables on a force platform. Shapiro-Wilk and Levine tests will be used to test the normality and homogeneity of the measurements, respectively. Two-way ANOVA (group x time) tests for repeated measures will be performed to assess changes over time and between groups for all dependent variables. Violation of sphericity will adjust using Greenhouse-Geser correction. The Bonferroni post-hoc test will detect specific differences between groups. When appropriate, the percentage of change (∆%) will be reported according to the following equation: ∆% = [(pre-average post average) / pre-average mean] × 100. Values will be express as mean ± standard deviation. O significance level α will be 0.05.

Official Title
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Effects of Laser Photobiomodulation (PBM) Therapy at 808 nm on Muscle Performance in Elderly Women: a Randomized, Controlled Trial

Conditions
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Lasers, Resistance Training, Muscle Strength, Aged, Performance

Intervention / Treatment
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* Radiation: Active laser
* Radiation: Placebo laser


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 65-80 y, Classified as eutrophic (i.e., body mass index ≤ 27 kg/m2), and Classified as physically active (i.e., performing at least 150 min/week of moderate physical activity) according to criteria of the International Physical Activity Questionnaire (IPAQ) for elderly Exclusion Criteria: To be tobacco product users To make use of any ergogenic supplement within six months prior to the start of the study; To make use of any medication that could affect the ability to perform the physical tests; To have any physiological (e.g., cardiorespiratory and metabolic diseases, uncontrolled hypertension, or diabetes) or physical limitation (e.g., orthopedic or rheumatic diseases, muscular injury, fibromyalgia, or pain) that could affect the ability to perform the physical tests, or To be unable to understand the informed consent document and provide a detailed description of their lifestyle.

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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Female

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: Basic Science
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active laser<br>Each participant will receive the application of the active laser on the rectus femoris muscle during the trials 1 (acute) and 2 (chronic). | Radiation: Active laser<br>* Participants will receive laser irradiation on the rectus femoris muscle of both legs immediately before the test (trial 1) and training (trial 2) sessions. A researcher blinded to the treatment conditions will apply the irradiation on eight points distributed over the muscle belly, using a gallium arsenide aluminum (Ga-As-Al) laser (λ: 808 nm) equipment. The points will placed at 25, 35, 50 and 75% of the total distance between the anterior superior iliac spine and superior border of the patella, bilaterally, with 2 cm of distance between each point.<br>* Other names: Active laser therapy;|
| Placebo Comparator: Placebo laser<br>Each participant will receive the application of the placebo laser on the rectus femoris muscle during the trials 1 (acute) and 2 (chronic). | Radiation: Placebo laser<br>* Participants will receive placebo irradiation on the rectus femoris muscle of both legs immediately before the test (trial 1) and training (trial 2) sessions. A researcher blinded to the treatment conditions will apply the placebo irradiation on eight points distributed over the muscle belly. The points will placed at 25, 35, 50 and 75% of the total distance between the anterior superior iliac spine and superior border of the patella, bilaterally, with 2 cm of distance between each point.<br>* Other names: Placebo laser therapy;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in vastus lateralis thickness | Muscle thickness measured by ultrasonography | Baseline and after 10 weeks | 
| Change in maximal dynamic strength by 1RM | 1RM for knee extension exercise. | Baseline and after 10 weeks | 
| Change in MVIC | MVIC using a portable fixed dynamometry (i.e., compression load cell) | Immediately after intervention (Trial 1), and baseline and after 10 weeks (Trial 2) | 
| Change in functional capacity | Functional capacity measured by short physical performance battery (SPPB) | Immediately after intervention (Trial 1). | 
| Change in balance | Balance performance using a force platform. | Baseline and after 10 weeks (Trial 2) | 
| Change in repetitions-to-failure | Repetitions-to-failure test on a knee extension machine. | Immediately after intervention (Trial 1), and baseline and after 10 weeks (Trial 2) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in lactate levels | Blood samples will be collected for analyse of the lactate levels after repetitions-to-failure test | Immediately after repetitions-to-failure test (trial 1) | 
| Change in perceived exertion | Perceived exertion after repetitions-to-failure test using the OMNI scale | Immediately after repetitions-to-failure test (trial 1) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Photobiomodulation, Muscle function, Elderly, Resistance exercise, Balance