Photobiomodulation therapy (PBMT) has recently been indicated as a potential therapeutic strategy in diverse health and sports contexts. However, its efficacy on muscle performance in female futsal players remains unknown. The purpose of this study was to investigate the dose-response effect of PBMT on muscle performance in female futsal players.
Background: Photobiomodulation therapy (PBMT) has recently been indicated as a potential therapeutic strategy in diverse health and sports contexts. However, its efficacy on muscle performance in female futsal players remains unknown. The purpose of this study is to investigate the dose-response effect of PBMT on muscle performance in female futsal players. Methods: In a crossover design, fifteen female futsal athletes (age: 18-30 years) will be randomized to receive 1 of 4 PBMT conditions (placebo, 300, 900, and 1260 joules \[J\]) on four occasions, separated by a 2-wk washout period. PBMT treatments will be applied on the quadriceps muscle of both legs using a device containing 200 light-emitting diodes (LEDs), immediately before the following tests (dependent variables): countermovement jump (CMJ) (i.e., flight time as indicator of muscle power), maximum voluntary isometric contraction (MVIC) for the leg extension exercise (i.e., muscle strength), and 3 sets of repetitions-to-failure (i.e., local muscular endurance) for the 45º leg press exercise, with recording of rating of perceived exertion (RPE) after each set. The fatigue index will be determined by the number of repetitions between sets 1 and 3. Statistical analyses will be performe using IBM SPSS Statistics for Windows (version 24.0; IBM Corp., Armonk, NY). Data will be tested for normality and homogeneity using the Shapiro-Wilk's and Levene's tests, respectively. One-way ANOVA tests will be performed to evaluate the differences in the fatigue index, flight time, and peak and mean torque between the treatment conditions (placebo, 300, 900, and 1260 J). Changes over time and between treatment conditions in maximum number of repetitions and RPE will be analyzed with two-way repeated measures ANOVA. Violation of sphericity was corrected using the Greenhouse-Geisser method. When significant differences will be confirmed with the ANOVA, multiple comparison testing will be performed using the Bonferroni post hoc correction to identify these differences. Values will be expressed as mean (standard deviation and 95% confidence interval). The significance level was set at p \< 0.05.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
15
Participants will be received placebo PBMT on the quadriceps muscle of both legs, immediately before physical tests, using a device containing 200 LEDs (100 red and 100 infrared)
Participants will be received PBMT at 300 J on the quadriceps muscle of both legs, immediately before physical tests, using a device containing 200 LEDs (100 red and 100 infrared)
Participants will be received PBMT at 600 J on the quadriceps muscle of both legs, immediately before physical tests, using a device containing 200 LEDs (100 red and 100 infrared)
Universidade Norte do Paraná
Londrina, Paraná, Brazil
Repetitions-to-failure
The repetitions-to-failure test in the 45º leg press exercise consists of 3 sets at 70% of 1RM, with a 60-s rest interval between each set. Participants will perform as many repetitions as possible until momentary failure (i.e., when the participant is unable to complete the concentric portion of their current repetition across the full range of motion despite using maximal effort), and the maximum number of repetitions in each set will be recorded.
Time frame: 10 minutes
Fatigue index (FI)
The fatigue index (FI) will be determined by the equation: \[(REPS3 - REPS1)/REPS1\]\*100, where: REPS3 = number of repetitions in set 3, multiplied by the load lifted, and REPS1 = number of repetitions in set 1, multiplied by the load lifted. The higher the FI value (%), the higher the level of muscle fatigue.
Time frame: 10 minutes
Rating of perceive exterion (RPE)
Rating of perceived exertion (RPE) will be recorded immediately after completion of each set using the OMNI-RES scale. The participants will be instructed to report the perceived exertion value by indicating a number on the OMNI-RES scale (0 for ''no effort'' and 10 for ''maximal effort'') that best represented their momentary exertion.
Time frame: 10 minutes
Countermovement vertical jump (CMJ)
The CMJ test will be performed on a force platform (BIOMEC400-412, EMG System to Brazil Ltda, São Paulo, Brazil) to assess the flight time. Participants will perform three CMJs, interspersed with 1 min of rest, and the highest flight time will be used as an indicator of muscle power. The test will began with the participant standing, knees extended, and hands fixed on the iliac crest region (hips). The participant then will flexed their legs at an angle of approximately 90º and then quickly extended their legs to maximize the height of the jump. Hands will be kepted on hips throughout the jump.
Time frame: 10 minutes
Maximum voluntary isometric contraction (MVIC)
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Participants will be received PBMT at 1260 J on the quadriceps muscle of both legs, immediately before physical tests, using a device containing 200 LEDs (100 red and 100 infrared)
The MVIC test for the leg extension exercise (bilateral) will be performed using an isometric dynamometer (CEFISE Biotechnology, São Carlos, Brazil). Briefly, participants will perform three MVICs at 120º of knee flexion (180º = full extension) lasting 5 s, interspersed with 5 s of rest. Participants will be instructed and verbally encouraged to exert maximum force during all attempts. The highest value obtained for peak and mean torque of the three MVICs will be used for the analysis.
Time frame: 10 minutes