Effect of 830 nm low-level laser therapy in exercise-induced skeletal muscle fatigue in humans

Therapeutic Photobiomodulation Before Strenuous Exercise Attenuates Shoulder Muscle Fatigue

CONTEXT

Photobiomodulation therapy (PBMT) applied as a preconditioning treatment before exercise has been shown to attenuate fatigue and improve skeletal muscle contractile function during high-intensity resistance exercise. Practical implications for preconditioning muscles with PBMT before fatiguing exercise include a safe and noninvasive means to enhance performance and reduce the risk of musculoskeletal injury.

OBJECTIVE

To examine the muscle fatigue-attenuating effects of PBMT on performance of the shoulder external-rotator muscle group when applied as a preconditioning treatment before high-intensity, high-volume resistance exercise.

DESIGN

Sham-controlled, crossover design.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty healthy men (n = 8) and women (n = 12) between the ages of 18 and 30 years.

INTERVENTION(S)

Photobiomodulation therapy was administered using a near-infrared laser (λ = 810/980 N·m, 1.8 W/cm2, treatment area = 80-120 cm2) to the shoulder external-rotator muscles at a radiant exposure of 10 J/cm2. Participants performed 12 sets of isokinetic shoulder exercise. Each set consisted of 21 concentric contractions of internal and external rotation at 60°/s. The sets were subdivided into 3 blocks of exercise (block 1: sets 1-4; block 2: sets 5-8; block 3: sets 9-12).

MAIN OUTCOME MEASURE(S)

Normalized peak torque (N·m/kg), average peak torque (N·m), total work (N·m), and average power (W).

RESULTS

During the last block of exercise (sets 9-12), all performance measures for the active PBMT condition were 6.2% to 10% greater than the sham PBMT values (P < .02 to P < .001).

CONCLUSIONS

Photobiomodulation therapy attenuated fatigue and improved muscular performance of the shoulder external rotators in the latter stages of strenuous resistance exercise.

Innovative integration: optimizing performance through warm-up and photobiomodulation in high-intensity test

We investigated whether the application of photobiomodulation therapy (PBMT) immediately after a standardized warm-up (WU + PBMT) or traditional PBMT (no pre-warming) would influence performance in intermittent testing and intensity variables. In a counterbalanced randomized crossover design, twelve female futsal players (mean age: 23.9 ± 3.8 years) attended four sessions. Each session involved either a standardized warm-up or maintaining seated rest for five minutes. Subsequently, PBMT or placebo (with the PBMT device turned off) was applied, followed by the YoYo Intermittent Recovery Level 1 test (YYIR1) during which we assessed heart rate, rating of perceived exertion, and blood lactate levels. The performance in YYIIR1 was superior (p = 0.02) in the WU + PBMT condition (440.0 ± 59.0 m) compared to the WU + Placebo (353.3 ± 94.7 m), and placebo alone (no warm-up) (325.0 ± 67.2 m). We conclude that a combination of a specific warm-up before PBMT application improves high-intensity intermittent performance in amateur female futsal players without affecting intensity variables.

Effects of photobiomodulation therapy on the functional performance of healthy individuals: a systematic review with meta-analysis

The aim of this study is to assess the effect of photobiomodulation therapy (PBMT) on functional performance concerning strength, fatigue, and functional capacity in healthy individuals. This systematic review with meta-analysis involved searches on data platforms and active searches of randomized clinical trials, focusing on PBMT as the sole intervention. Primary outcomes assessed included strength, fatigue, and functional capacity. Three reviewers screened studies by title and abstract using Rayyan, and data were extracted using a specific form. Bias risk was assessed using RoB2, and confidence in the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The RevMan was used for meta-analysis. Sixteen studies were included, totaling 340 individuals (183 males and 157 women). Most articles presented a low risk of bias. Variability was observed in device types and application domains, including wavelengths (655-905 nm), power (10-200 nW), energy (0.6-30 J per point), and time (30-100 s per point). PBMT improved fatigue recovery (mean difference: 5.87; 95% CI 3.83, 7.91). There was no enhancement in strength (peak torque: mean difference 12.40; 95% CI -5.55, 30.55; one-repetition maximum test: mean difference 39.97, 95% CI -2.44, 82.38; isometric and isokinetic strength: mean difference 2.77, 95% CI -14.90, 20.44) nor improvement in short-term (mean difference 0.67, 95% CI -0.58, 1.91) and long-term (mean difference 18.44, 95% CI -55.65, 92.54) functional capacity. PBMT may aid in favoring fatigue recovery in healthy individuals; however, there's no evidence to support PBMT enhancing strength or improving functional capacity.

Effects of Photobiomodulation and Low-Intensity Stretching on Delayed-Onset Muscle Soreness: A Randomized Control Trial

Objective: This study aimed to investigate the effects of photobiomodulation (PBM), low-intensity stretching, and their combination on delayed-onset muscle soreness (DOMS) in the untrained population. The relationships between DOMS and muscle function and functional performance were also tested. Methods: Fifty-four participants were randomized into four groups. Eccentric exercise was used to induce DOMS. Each group received either no treatment, PBM, stretching or PBM combined with stretching at 24, 48, and 72 h postexercise. Pressure pain threshold (PPT), numerical rating scale (NRS), single-leg forward jump (SLFJ), and maximum isometric voluntary contraction (MIVC) were measured at baseline, 24, 48, 72, and 96 h after eccentric exercise. Between-group differences were tested using two-way repeated measures analysis of variance and the relationships between DOMS and MIVC, and SLFJ were examined using Pearson's correlation analysis. Results: The PPT at the vastus medialis and vastus lateral in the PBM combined with stretching group was significantly lower than that in control group at 72 h (p = 0.045) and 48 h (p = 0.037) postexercise. No significant between-group difference in PPT was found for the rest occasions. There was no significant between-group difference in NRS, MVIC, and SLFJ on any occasion (p ≥ 0.052). DOMS was not correlated with MIVC and SLFJ (p ≥ 0.09). Conclusions: PBM or low-intensity stretching did not affect DOMS and functional performance in untrained individuals. The combination of PBM and low-intensity stretching increased pain sensitivity and did not relieve soreness. The DOMS was not associated with either muscle function or functional performance.

Deconstructing the Ergogenic Effects of Photobiomodulation: A Systematic Review and Meta-analysis of its Efficacy in Improving Mode-Specific Exercise Performance in Humans

BACKGROUND

Photobiomodulation therapy (PBMT) is defined as non-thermal electromagnetic irradiation through laser or light-emitting diode sources. In recent decades, PBMT has attracted attention as a potential preconditioning method. The current meta-analysis was conducted to assess the effectiveness of PBMT in improving mode-specific exercise performance in healthy young adults.

METHODS

A computerized literature search was conducted, ending on 15 May 2022. The databases searched were PubMed, Cochrane Central Register of Controlled Trials, Embase, SPORTDiscus, and the Physiotherapy Evidence Database. Inclusion/exclusion criteria limited articles to crossover, double-blind, placebo-controlled studies investigating the PBMT effects as a preconditioning method. The included trials were synthesized according to exercise mode (single-joint, cycling, running, and swimming). All results were combined using the standardized mean differences (SMDs) method and the 95% confidence intervals (CIs) were described.

RESULTS

A total of 37 individual studies, employing 78 exercise performance measurements in 586 participants, were included in the analyses. In single-joint exercises, PBMT improved muscle endurance performance (SMD 0.27, 95% CI 0.12-0.41; p < 0.01) but not muscle strength performance (p = 0.92). In cycling, PBMT improved time to exhaustion performance (SMD 0.35, 95% CI 0.10-0.59; p < 0.01) but had no effect on all-out sprint performance (p = 0.96). Similarly, PBMT had no effect on time to exhaustion (p = 0.10), time-trial (p = 0.61), or repeated-sprint (p = 0.37) performance in running and no effect on time-trial performance in swimming (p = 0.81).

CONCLUSION

PBMT improves muscle endurance performance in single-joint exercises and time to exhaustion performance in cycling but is not effective for muscle strength performance in single-joint exercises, running, or swimming performance metrics.

Feasibility study of a LED light irradiation device for the treatment of chronic neck with shoulder muscle pain/stiffness

Neck with shoulder muscle stiffness/pain is a common disorder. Commonly used physical therapy, pharmacotherapy, acupuncture, and moxibustion only temporarily alleviate the disorder in most cases, thus the disorder often recurs. Low power laser therapy is often used for neck and shoulder stiffness/pain and has been effective in clinical trials. In this study, we evaluated the safety and effectiveness of a newly developed self-care device for disorders including neck with shoulder muscle stiffness/pain. The device incorporates light-emitting diodes (LEDs), which are safer than lasers, as its light source. Ten adults with neck with shoulder muscle stiffness/pain were subject to LED irradiation (wavelength 780 nm ± 15 nm, output 750 mW, power density 3.8 W/cm2, energy density 5.7×102 J/cm2) for 3 minutes on the affected shoulder at a standard acupuncture point (GB21, Jianjing). Immediately after irradiation, the subjective symptoms of the neck with shoulder muscle stiffness and pain evaluated by a visual analog scale were improved from 58.3 mm ± 18.7 mm to 45.5 mm ± 21.5 mm and from 45.8 mm ± 23.3 mm to 39.4 mm ± 21.8 mm, respectively. The symptoms further improved after 15 minutes of irradiation. The skin temperature at the irradiated point increased from 34.3°C ± 1.1°C to 41.0°C ± 0.7°C. The increase in skin temperature was observed within approximately 5 cm of the irradiated area. There was no effect on the heart rate variability, a measure of the autonomic nervous system; however, the baroreflex sensitivity was slightly increased. No irradiation-related adverse skin events were observed. Our LED irradiation device was found to be safe, and it improved the subjective symptoms of muscle stiff neck with shoulders.

Impact of body fat, body water content, and skeletal muscle mass index on peak salivary lactate levels after squat jump exercise in healthy non-athlete adult males

BACKGROUND

In the rehabilitation and sports science fields, comprehensive assessment of the response to exercise is important for accurately prescribing exercise programs. Lactate is an important energy substrate that is frequently measured in clinical practice because it provides information on aerobic capacity. Salivary lactate, which can be measured non-invasively, has recently been focused on as an alternative to blood lactate. This study aimed to determine the combined effects of body fat, body water content, and skeletal muscle mass index on peak salivary lactate levels.

METHODS

Thirty-seven non-athletic males performed a squat jump exercise. Their salivary lactate levels were measured before, immediately after, and every 5 min after the exercise using a simplified device. We also assessed body composition. A linear multiple regression analysis was performed with peak salivary lactate levels as the dependent variable and body fat ratio, body water content, and the skeletal muscle mass index as independent variables.

RESULTS

The participants' body fat ratio (positive effect; p = 0.001) and body water content (negative effect; p = 0.035) significantly affected peak salivary lactate levels. Skeletal muscle mass index tended to positively influence salivary lactate levels (p = 0.099), albeit not significantly. The adjusted R-squared value of the model was 0.312 (p = 0.001).

CONCLUSIONS

The combined effect of body fat, body water content, and skeletal muscle mass index on peak salivary lactate levels was 31.2%. Better nutritional guidance may be effective in promoting weight loss and increasing body water content to improve aerobic capacity in the rehabilitation setting.

Effectiveness of High Power Laser Therapy on Pain and Isokinetic Peak Torque in Athletes with Proximal Hamstring Tendinopathy: A Randomized Trial

Athletes such as long-distance runners, sprinters, hockey, and/or football players may have proximal hamstring tendinopathy (PHT). Laser therapy has been shown to be effective in tendinopathies. High power laser therapy (HPLT) is used for the treatment of several musculoskeletal conditions; however, its efficacy on PHT has not been investigated. This study is aimed at examining the effects of HPLT on pain and isokinetic peak torque (IPT) in athletes with PHT. The two-arm comparative pretest-posttest experimental design was used with random allocation of 36 athletes aged 18-35 years into two groups (experimental and conventional group). The experimental group included the application of HPLT for 3 weeks. The conventional group included treatment with a conventional physiotherapy program including ultrasound therapy, moist heat pack, and home exercises for a total of 3 weeks. Pain and IPT of the hamstring muscle were measured before and after the application of the intervention. Pain score decreased, and IPT increased significantly (p < 0.05) after application of HPLT, by 61.26% and 13.18%, respectively. In the conventional group, a significant difference (p < 0.05) was observed in pain scores only, which decreased by 41.14%. No significant difference (p > 0.05) was observed in IPT in the conventional group. When HPLT was compared with conventional physiotherapy, a significant difference was found in pain scores only. HPLT for 3 weeks was found to be effective in improving pain in athletes with PHT. However, no significant difference was found between HPLT and conventional physiotherapy (US, moist heat, and home exercises) in improving the IPT of the hamstring muscle.

Low-energy laser therapy application on knee joints as an auxiliary treatment in patients with polyarticular juvenile idiopathic arthritis: a dual-arm randomized clinical trial

Patients with juvenile idiopathic arthritis (JIA) always experience persistent pain and stiffness which induces muscle weakness, fatigue, and functional limitations. This study evaluated whether applying low-energy laser therapy (LLT) on the knee joint could be an effective adjuvant intervention for patients with JIA. Sixty children with polyarticular JIA participated and were randomly allocated to receive either LLT (wavelength λ = 903 nm; power output of 50 mW; and energy of 1.5 J) plus exercises (LLT group) or exercises alone (control group). Pain, peak concentric torque of quadriceps muscles, fatigue, and functional status were measured by the visual analogue scale, isokinetic testing system, Pediatric Quality of Life Inventory Multidimensional Fatigue Scale, and Childhood Health Assessment Questionnaire, respectively pre- and post-intervention, and at 6-month follow-up. Per the mixed-model analysis of variance, the LLT group showed a statistically more favorable improvement in pain (P = .003, η_p² = .014), fatigue perception (P = .004, η_p² = .015), and functional status (P = .022, η_p² = .09) across the three assessment occasions, as compared to the control group. However, no significant difference was demonstrated between both groups concerning peak concentric torque (all P > .05). Incorporation of LLT into the standard physical rehabilitation program for patients with JIA has the potential to induce more conducive improvements in pain, fatigue, and functional performance, but is not effective for improving muscle performance.

Effects of Low-Level Laser Therapy on Muscular Performance and Soreness Recovery in Athletes: A Meta-analysis of Randomized Controlled Trials

CONTEXT

Athletes must maintain their peak state of strength. Previous studies have investigated the effect of low-level laser therapy (LLLT) on muscular performance. A previous systematic review and meta-analysis has investigated this issue in healthy participants but not in physically active athletes.

OBJECTIVE

To investigate whether LLLT can improve muscular performance and soreness recovery in athletes.

DATA SOURCES

PubMed, EMBASE, and Cochrane Library.

STUDY SELECTION

Published randomized controlled trials and crossover studies till December 2020.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Assessment of study quality was rated using the risk of bias assessment method for randomized trials (Cochrane Handbook for Systematic Reviews of Interventions).

RESULTS

A total of 24 studies were included. LLLT application before exercise significantly improved lower-limb muscle strength in 24-hour, 48-hour, 96-hour, and 8-week follow-up groups. Furthermore, decreased soreness index, serum creatine kinase concentrations, interleukin-6, and thiobarbituric acid reactive substance concentrations and a trend toward the improvement of contract repetition number and VO₂ kinetic outcomes were observed.

CONCLUSION

Although a definite therapeutic effect of LLLT is yet to be established, the current evidence supports that LLLT use improves muscular performance in physically active athletes. Additional trials with large sample sizes and robust design should be conducted before strong recommendations are made.

Photobiomodulation Therapy at 808 nm Does Not Improve Biceps Brachii Performance to Exhaustion and Delayed-Onset Muscle Soreness in Young Adult Women: A Randomized, Controlled, Crossover Trial

Objective

This study aims to investigate the effects of laser photobiomodulation (PBM) at 808 nm on biceps brachii performance to exhaustion, rating of perceived exertion (RPE), and delayed onset muscle soreness (DOMS) in untrained young women.

Methods

Thirteen young women (20.1 ± 2.9 years) participated in a crossover study in which they received, in a counterbalanced manner, active and placebo laser PBM on two occasions (T1 and T2), separated by a 7-day washout period. During T1 and T2, participants received active (100 mW output power, irradiance of 35.7 W cm^–2, and total energy of 28 J/arm) or placebo laser irradiation on the biceps brachii muscle at 20 min before the repetitions-to-failure test [six sets at 60% of one-repetition maximum (1RM) until failure] for elbow flexion exercise. The number of repetitions performed and RPE over the six sets, as well as DOMS from basal up to 72 h after the repetitions-to-failure test, were recorded.

Results

There was a significant (time, p < 0.05) reduction in the number of repetitions performed and an increase in RPE over six sets, with no statistical differences between placebo and active laser conditions (treatment × time, p > 0.05). DOMS increased at 24 h postexercise and progressively returned to baseline after 72 h in both conditions (time, p < 0.05; treatment × time, p > 0.05).

Conclusion

Our results indicate that acute laser PBM at 808 nm does not improve biceps brachii performance to exhaustion, RPE, and DOMS in untrained women.

Effects of Photobiomodulation/Laser Therapy Combined With Resistance Training on Quadriceps Hypertrophy and Strength, and Postural Balance in Older Women: A Randomized, Triple-Blinded, Placebo-Controlled Study

BACKGROUND AND PURPOSE

Physical and therapeutic strategies to maintain and rehabilitate skeletal muscle mass, strength, and postural balance are clinically relevant to improve the health, well-being, and quality of life of older adults. The purpose of this study was to investigate the effects of photobiomodulation (PBM)/laser therapy combined with a resistance training (RT) program on quadriceps hypertrophy and strength, and postural balance in older women.

METHODS

In a randomized, triple-blinded, placebo-controlled design, twenty-two older women (age 66.6 ± 5.2 years) were engaged in a supervised 10-wk RT program (2 times per week) involving unilateral leg extension exercise, in which each leg of the same participant was randomly assigned to receive active (λ = 808 nm, optical output = 100 mW, total energy = 42 J) or placebo laser PBM immediately before the RT sessions. Maximal dynamic strength by unilateral knee extension 1-repetition maximum (1RM), muscle hypertrophy by vastus lateralis muscle thickness, and postural balance by one-legged stance test on a force platform were assessed before and after the training program.

RESULTS

Significance statistical analysis revealed a similar improvement (time P = .003) from pre- to posttraining for muscle hypertrophy and strength, and postural balance between active and placebo laser conditions. However, clinical interpretation for muscle hypertrophy showed a moderate effect (effect size [ES] = 0.58) for the active laser and a small effect (ES = 0.38) for the placebo laser. Clinical difference was not noticed between conditions for other analyzed variables.

CONCLUSIONS

These findings indicate that RT alone can be clinically important for counteracting the deleterious effects of aging on muscle size, strength, and balance, and that applying laser PBM therapy before the RT sessions may further improve gains in muscle hypertrophy.

A Novel Blue-Red Photobiomodulation Therapy Patch Effects on a Repetitive Elbow-Flexion Fatigue Task

BACKGROUND

Photobiomodulation (laser/light) therapy has reduced skeletal muscle fatigue and improved performance in previous research.

OBJECTIVE

To determine if the application of a novel blue (450 nm) and red (645 nm) light-emitting diode photobiomodulation therapy patch improves muscle function and decreases perceived exertion after an elbow-flexion fatigue protocol.

PARTICIPANTS

Thirty-four strength-trained individuals (male = 32 and female = 2, age = 22.5 [2.7] y).

METHODS

Participants were randomly assigned to an active or placebo treatment. On  visit 1, participants' 1-repetition maximal biceps curl was determined, and an orientation session of the fatigue task occurred to ensure no learning effects. Fifty percent of the participants' 1-repetition maximum was used during the fatigue protocol. On visit 2, participants performed biceps curl repetitions at a speed of 25 repetitions per minute until they could not physically move the weight past 90° of elbow flexion or stay with the set pace. After the fatigue protocol, a 30-minute blue/red light (wavelength = 450 and 645 nm, peak irradiance = 9 mW/cm2, duty cycle = pulsed 33%, and fluence = 5.4 J/cm2) or sham treatment was administered based on the randomized group assignment. Immediately following, the participants repeated the fatigue protocol. The number of complete repetitions was counted, and the participants rated their perceived level of exertion on the Borg scale immediately after each fatigue bout.

RESULTS

Overall, fatigue occurred between the 2 exercise bouts (pretreatment = 44.1 [12.3] and posttreatment = 37.4 [9.6] repetitions, P = .02). However, less fatigue was noted in the number of participants of the active treatment group than the sham treatment group. During the posttreatment fatigue task, 29.4% of participants in the active treatment group improved compared to 0% in the sham treatment (P = .045).

CONCLUSION

Nearly 30% of participants had an increase benefit during a repeated-bout fatigue task due to the blue/red light-emitting diode photobiomodulation light patch.

Convergent validity of a simplified device and relationship between blood lactate and salivary lactate after a vertical squat jump in healthy non-athletes

[Purpose] The aims of this study were 1) to examine the convergent validity between Lactate pro 2 and a standard JCA-BM 8000 automatic analyzer using salivary lactate and 2) to investigate the relationship between blood and salivary lactate levels after a vertical squat jump. [Participants and Methods] Healthy non-athletes participated in this observational study. The participants performed a vertical squat jump for 1 min 30 s. Blood and salivary lactate levels were measured before and after exercise using Lactate Pro 2. [Results] The intraclass correlation coefficient between Lactate Pro 2 and the JCA-BM 8000 automatic analyzer was 0.773, which can be considered as substantial convergent validity. However, in some samples, the salivary lactate level was out of the measurable range, and numerical values could not be obtained. The cross-correlation function between the blood and salivary lactate levels was 0.535 at lag 0 and 0.750 at lag 1, which indicated a 5-min lag between the salivary and blood lactate values. [Conclusion] Salivary lactate levels can be easily measured using Lactate Pro 2, although its sensitivity needs to be resolved. Further research is required for salivary lactate level, which can be collected non-invasively, to be used as an alternative parameter to blood lactate level.

Effects of 830 nm Light-Emitting Diode Therapy on Delayed-Onset Muscle Soreness

Objectives. Our study investigated the effects of 830 nm light-emitting diode therapy (LEDT) for postexercise delayed-onset muscle soreness (DOMS). Methods. In this randomized control study, healthy participants were randomized into LEDT and placebo groups. LEDT (output frequency = 10 Hz; wavelength = 830 nm; total output power = 210 mW; and dose = 315 J/cm2) was applied to six sites in the damaged quadriceps for 10 min. The placebo group received sham LEDT with no energy output. The nondominant leg was chosen for DOMS induction, using an eccentric exercise. Visual analog scale (VAS) scores for muscle soreness, pressure pain threshold (PPT), thigh circumference, joint range of motion, and muscle strength were assessed before and immediately after exercise and at 24, 48, 72, and 96 h postexercise. Results. Forty participants were divided into the LEDT group (n = 20) and the placebo group (n = 20). Compared with the placebo group, the LEDT group exhibited significant increases in PPT values at 48, 72, and 96 h postexercise ( $p<0.05$ ). The joint range of motion was significantly different between the LEDT and placebo groups at 72 and 96 h postexercise ( $p<0.05$ ). No significant intergroup differences were noted in thigh circumference and muscle strength ( $p<0.05$ ). Conclusion. The application of 830 nm LEDT on postexercise DOMS pain exerted an analgesic effect but did not affect the muscle repair process. Future studies should elucidate the beneficial effects of 830 nm LEDT on muscle recovery or performance.

Photobiomodulation Before Eccentric Fatigue Protocol in the Control of Pain and Muscle Damage Markers: A Double-Blind, Randomized Controlled Study

Background: Several strategies are used in the management of delayed-onset muscle soreness (DOMS), but there is not always evidence to justify its use. Photobiomodulation (PBM) is a noninvasive means, with promising previous results of its use in this outcome. Objective: This study aimed to identify the effects of PBM in the femoral quadriceps region to reduce DOMS in men undergoing a fatigue protocol. Methods: This is a double-blind, randomized controlled study. The sample consisted of 35 physically active men. The volunteers were divided into two groups: pre-fatigue PBM [Group 1 (G1)] and post-fatigue PMB [Group 2 (G2)]. The fatigue test was conducted at the same time of day. Given this was a crossover study of volunteers, we used at least a 1-week washout to avoid any residual interference from the previous intervention. PBM (active/placebo) was performed 5 min before the start of the fatigue protocol in G1 and immediately after the fatigue protocol in G2. PBM was applied at six points on the femoral quadriceps muscle (cluster laser/light emitting diodes 13, 415 mW, 30.2 J per point, 73 sec per application, and total dose of 181.2 J). In the data analysis, the primary endpoint was DOMS measured using a Numerical Pain Scale, and the secondary outcome was examined on the effects of PMB muscle damage, muscle contraction, and isometric horizontal jump. Results: There were significant differences to PBM compared with the placebo group for DOMS, with no differences between the times of application. For muscle damage, there was significant difference (p > 0.05) when PBM was applied in pre-fatigue. G1 led to an increase of 14.9% in the creatine kinase level when active since the application of placebo PBM increased by 65% (p = 0.04). Conclusions: The PBM applied before eccentric fatigue protocol showed no significant results on DOMS, although there was a positive effect to control muscle damage. Brazilian Registry of Clinical Trials (RBR-7qhddz).

Acute Photobiomodulation Effects Through a Cluster Device on Skeletal Muscle Fatigue of Biceps Brachii in Young and Healthy Males: A Randomized Double-Blind Session

Objective: The aim of this study was to investigate and compare the acute effects of red and infrared photobiomodulation (PBM) using a cluster device on biceps brachii muscle fatigue in young and healthy males. Background: Vigorous physical activity could lead to muscle fatigue, which compromises motor control and muscle strength and consequently impairs performance. The positive effects of PBM in reducing fatigue onset have been highlighted. However, the better wavelength with cluster devices is not yet established. Methods: A randomized double-blind session was used. Thirty-two young and healthy males were randomized into the control group (CG), red PBM group (RPG), and infrared PBM group (IPG). A PBM cluster device [7 visible diodes (630 nm), 7 infrared diodes (850 nm), 100 mW/diode, 2 W/cm² power density, 91 J/cm² energy density, 4 J per point, 28 J total energy, and 40 sec] was applied after muscle fatigue. Muscle fatigue was analyzed by surface electromyography (EMG) recorded from the long head of biceps brachii, blood lactate concentration, and evaluation of the rate of perceived exertion (RPE) using the Borg Scale. The fatigue protocol consisted of a maximum voluntary isotonic contraction of elbow flexion-extension with 75% of one-repetition maximum until exhaustion. The Borg Scale was applied before and at the end of the experiment to measure the RPE. The electromyography fatigue index (EMGFI) was calculated by windows of median frequency from EMG data. Results: EMGFI, blood lactate concentration, and RPE showed no intergroup statistical difference, except the EMGFI delta value that showed a difference between IPG and CG, with a greater value in the CG. However, intragroup comparisons showed that EMGFI decreased in the CG and RPE and lactate concentration increased significantly in all groups. Conclusions: There was no difference between red and infrared PBM in reduction of biceps brachii fatigue. However, the EMGFI delta value was greater in the IPG compared with the CG, suggesting that infrared can be more effective in reducing biceps brachii fatigue.

What is the optimal time-response window for the use of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) for the improvement of exercise performance and recovery, and for how long the effects last? A randomized, triple-blinded, placebo-controlled trial

Background

The optimal time-response window for photobiomodulation therapy (PBMT) using low-level laser therapy (LLLT) and/or light emitting diodes therapy (LEDT) combined with static magnetic fields (sMF) before physical activity still was not fully investigated. The aim of the present study was to investigate the better of four time-response windows for PBMT combined with sMF (PBMT-sMF) use before exercise in humans.

Methods

A prospectively registered, randomized, triple-blinded (volunteers, therapists and assessors) placebo-controlled trial was carried out. Sixty healthy untrained male subjects were randomly allocated to six experimental groups (n = 10 per group): PBMT-sMF 5 mins, PBMT-sMF 3 h, PBMT-sMF 6 h, PBMT-sMF 1-day, placebo, and control. The control group performed all procedures, however did not receive any kind of intervention. PBMT-sMF active or PBMT-sMF placebo was applied precisely in different time points after baseline MVC test to ensure that both MVC tests and eccentric exercise protocol would occur at the same hour of the day in all groups. Then, after five minutes, 3 h, 6 h or 1-day (24 h) of PBMT-sMF treatment (active or placebo) the eccentric exercise protocol was performed. The primary outcome was peak torque obtained from maximum voluntary contraction (MVC). The secondary outcomes were creatine kinase (CK), and delayed onset muscle soreness (DOMS). The primary and secondary outcomes were measured at baseline, immediately after, 1 h, 24 h and 48 h after the eccentric exercise protocol.

Results

Sixty patients were randomized and analyzed to each sequence. The outcomes in absolute values show that all active PBMT-sMF groups increased (p < 0.05) MVC from immediately after to 1 h after eccentric exercise, and decreased (p < 0.05) CK activity at all time points. However, PBMT-sMF 5 mins, 3 h and 6 h groups showed better results in MVC and CK analysis from 24 h to 48 h, and also to DOMS (p < 0.05) at all time points. Participants did not report any adverse events.

Conclusions

PBMT-sMF can be used from 5 min to 6 h before exercise, and the effects can last up to 54 h after treatment. However, the effects start to decrease when a 1-day (24 h) time-response window is used.

Trial registration

NCT03420391. Registered 05 February 2018.

Acute Photobiomodulation Does Not Influence Specific High-Intensity and Intermittent Performance in Female Futsal Players

The acute improvement of performance after photobiomodulation therapy (PBMT) has been reported in different types of exercise. However, the effect on high-intensity and intermittent exercises that are relevant for team sports is unknown. Thus, we evaluated the effect of prior acute application of PBMT on high-intensity and intermittent exercise performance, muscle oxygenation, and physiological/perceptual indicators in amateur female futsal players. Thirteen players (24.1 ± 3.7 years) performed a testing battery (countermovement jump (CMJ), Illinois agility and YoYo intermittent recovery test level 1 (YYIR1)) preceded by 15 min of PBMT (1 min 30 s each muscular point; five muscular points in each lower limbs) or 15 min of placebo (SHAM), in a counterbalanced randomized cross-over design (one-week in-between PBMT/SHAM). All test performance did not differ (p > 0.05) between PBMT and SHAM, as well as blood lactate, rating of perceived exertion, heart rate, and muscle oxygenation (via near infrared spectroscopy) responses. The acute application of PBMT prior to a physical testing battery does not influence high-intensity and intermittent exercises performance, neither physiological nor perceptual responses in amateur female futsal players.

Does Photobiomodulation Therapy Enhance Maximal Muscle Strength and Muscle Recovery?

Photobiomodulation has been shown to improve tissue and cell functions. We evaluated the influence of photobiomodulation, using a B-Cure laser, on: 1) maximal performance, and 2) muscle recovery after resistance exercise. Two separate crossover randomized double-blinded placebo-controlled trials were conducted. Sixty healthy physical education students (28 men, 32 women), aged 20-35, were recruited (30 participants for each trial). Participants performed two interventions for each experiment, with real lasers (GaAlAs, 808 nm) on three quadricep locations in parallel (overall treatment energy of ~150J) or sham (placebo) treatment. In the first experiment muscle total work (TW) and peak torque (PT) were measured by an isokinetic dynamometer in five repetitions of knee extension, and in the second experiment muscle recovery was measured after the induction of muscle fatigue by evaluating TW and PT in five repetitions of knee extension. There were no differences between treatments (real or sham) regarding the TW (F(1,28) = 1.09, p = .31), or PT (F(1,29) = .056, p = .814). In addition, there was no effect of photobiomodulation on muscle recovery as measured by the TW (F(1,27) = .16, p = .69) or PT (F(1,29) = .056, p = .814). Applying photobiomodulation for 10 min immediately before exercise did not improve muscle function or muscle recovery after fatigue.

Comparison of the effects between lasers applied to myofascial trigger points and to classical acupoints for patients with cervical myofascial pain syndrome

Background

To compare the immediate effectiveness of low-level laser therapy (LLLT) applied to classical acupoints versus trigger points for patients with cervical myofascial pain syndrome (MPS).

Methods

This was a single-blinded, randomized, placebo-controlled trial. This study was performed in a university-affiliated medical center. One hundred participants with cervical myofascial pain syndrome were randomly allocated to four treatment groups, including (1) acupoint therapy (AcuT), (2) acupoint control (AcuC), (3) trigger point therapy (TriT), and (4) trigger point control (TriC) groups. Low-level laser (810-nm) therapy was used in both therapy groups, while the same procedure was performed without laser in the acupoint control groups. The patients were evaluated based on visual analogue scale (VAS) pain score, pressure pain threshold, and cervical range of motion (ROM) before and after the therapy.

Results

Immediate pain relief was observed in the TriT group (p < 0.01). The TriT group showed improved cervical ROM in ipsilateral bending (p < 0.01), while the AcuT group did not.

Conclusions

LLLT applied to trigger points could significantly relieve myofascial pain and was effective in relieving cervical ROM limitations. Considering the risk of pneumothorax, laser therapy at trigger points for patients with cervical MPS may be a choice when acupuncture therapy is unavailable.

Trial registration

ClinicalTrials.gov ID: NCT01516502.

Phototherapy on Management of Creatine Kinase Activity in General Versus Localized Exercise: A Systematic Review and Meta-Analysis

OBJECTIVE

The main focus of this systematic review was to determine the efficacy of phototherapy in the management of creatine kinase (CK) activity after exercise and furthermore to identify for which exercise model protocol phototherapy provides the best results.

DESIGN

Meta-analysis comparing phototherapy with a control condition.

SETTING

The MEDLINE, EMBASE, SPORTDiscus, PEDro, and CENTRAL databases were searched from their earliest records to October 03, 2016. Data were pooled in a meta-analysis and described as standardized mean difference (SMD) with 95% confidence intervals (CIs) using a random effects model.

PARTICIPANTS

Healthy subjects (no restrictions were applied, eg, age, sex, and exercise level).

INTERVENTION

Phototherapy (low-level laser therapy and/or light-emitting diode therapy) before or after exercise and a placebo or control condition.

MAIN OUTCOME MEASURES

Creatine kinase activity (no restriction to any analysis, eg, serum, plasma, or capillary blood).

RESULTS

Fourteen studies were included for review. The results revealed that phototherapy has a more positive effect than control condition in management of CK activity [SMD = 0.77, 95% CI (0.32 to 1.22); P = 0.0007; I = 72%]. In exploratory analysis, the results showed that phototherapy was effective only in the exercise protocol with localized exercise with large effect size [localized exercise: SMD = 0.89, 95% CI (0.26 to 1.51); P = 0.0002; I = 76%; general exercise: SMD = 0.61, 95% CI (-0.05 to 1.26); P = 0.07; I = 67%].

CONCLUSIONS

The available evidence suggest that phototherapy has beneficial effects on the management of CK activity and demonstrate a possible relationship based on damage caused by exercise, providing a greater effect in studies that used localized exercise.

Effects of photobiomodulation therapy combined to static magnetic field in strength training and detraining in humans: protocol for a randomised placebo-controlled trial

INTRODUCTION

In recent years, it has been demonstrated that photobiomodulation therapy (PBMT) using low-level laser therapy and/or light-emitting diode therapy combined to static magnetic field (sMF) has ergogenic effects, improving muscular performance and accelerating postexercise 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/sMF in detraining after a strength-training protocol.

METHODS AND ANALYSIS

The study will be a randomised, triple-blind, placebo-controlled clinical trial. Healthy male volunteers will be randomly distributed into four experimental groups: PBMT/sMF before training sessions + PBMT/sMF during detraining, PBMT/sMF before training sessions + placebo during detraining, placebo before training sessions + PBMT/sMF during detraining and placebo before training sessions + placebo during detraining. Strength-training sessions will be carried out over 12 weeks, and the detraining period will occur during the 4 weeks after. The muscular strength and the structural properties of quadriceps will be analysed.

ETHICS AND DISSEMINATION

This study was approved by the Research Ethics Committee of Nove de Julho University. The results from this study will be disseminated through scientific publications in international peer-reviewed journals and presented at national and international scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03858179.

Efficacy of laser therapy for exercise-induced fatigue: A meta-analysis

BACKGROUND

Laser therapy is widely used for exercise-induced fatigue, while the effect among different studies remains controversial. The present study was to summary available randomized controlled trials (RCTs) to evaluate the effect of laser therapy in subjects with exercise-induced fatigue.

METHODS

PubMed, Embase, and Cochrane Library were searched to identify the potential RCTs from inception to October 2017. The weighted mean difference (WMD) with 95% confidence intervals (CIs) was calculated using a random-effects model.

RESULTS

Twenty RCTs involving a total of 394 individuals were included in final analysis. No significant differences were observed between the laser therapy and control for the outcomes of lactate (WMD: -0.19; 95%CI: -0.52 to 0.13; P = .244), repetitions (WMD: 4.44; 95%CI: -1.43 to 10.32; P = .138), work load (WMD: 3.38; 95%CI: -1.15 to 7.91; P = .144), time taken to perform the exercise tests (WMD: 4.42; 95%CI: -2.33 to 11.17; P = .199), creatine kinase (WMD: -41.80; 95%CI: -168.78 to 85.17; P = .519), maximum voluntary contraction (WMD: 23.83; 95%CI: -7.41 to 55.07; P = .135), mean peak forces (WMD: 2.87; 95%CI: -1.01 to 6.76; P = = .147), and visual analog scale (VAS) (WMD: -1.91; 95%CI: -42.89 to 39.08; P = = .927). The results of sensitivity analysis suggested that laser therapy might play an important role on the levels of lactate (WMD: -0.30; 95%CI: -0.59 to -0.01; P = = .040), maximum voluntary contraction (WMD: 33.54; 95%CI: 1.95 to 65.12; P = = .037), and VAS (WMD: -21.00; 95%CI: -40.78 to -1.22; P = = .037). The results of subgroup analyses indicated no significant differences between the laser therapy and placebo for lactate and repetitions when stratified by study design, mean age, gender, and study quality.

CONCLUSIONS

The findings of this meta-analysis did not indicate any significant differences between the laser therapy and placebo.

Analysis of the effects of low-level laser therapy on muscle fatigue of the biceps brachii muscle of healthy individuals and spastic individuals: Study protocol for a single-center, randomized, double-blind, and controlled clinical trial

BACKGROUND

Muscular fatigue is caused by biochemical alterations that modify the mechanics of muscle contraction, resulting in negative changes in the performance of the contraction. Several resources are studied to mitigate this situation among which we can cite low-level laser therapy (LLLT). The effects of LLLT are being studied in healthy subjects with fibromyalgia and who are athletes, and currently the studies are being performed in spastic muscles with poststroke individuals. The aim will be to evaluate the effects of LLLT on the fatigue of the biceps brachii muscle of healthy individuals and individuals with spastic hemiparesis.

METHODS

A cross-sectional, comparative, randomized, placebo, double-blind clinical trial will be divided into 2 phases: phase I shall consist of 30 healthy subjects and phase II of 30 poststroke individuals. The study will consist of 3 groups (control group, placebo group, and LLLT group), and all individuals will pass through all groups, following the randomization criteria. The protocol consists of the application of LLLT in the biceps brachii muscle on the dominant side in healthy individuals and in the hemiparetic side of poststroke individuals, and, subsequently, 3 maximal isometric voluntary contractions (MIVCs) will be performed for 50 seconds in the dynamometer, with an interval of 50 seconds between them. Pain intensity will be evaluated by means of the visual analog scale, and the myoelectric activity by means of surface electromyography associated with the evaluation of muscular strength by means of the dynamometer. The local temperature will be evaluated by infrared thermography and blood lactate concentration through the lactimeter, which will be measured at 4 different times, before the application of the laser (basal), and 3, 15, and 25 minutes after the MIVC.

Effects of photobiomodulation therapy in aerobic endurance training and detraining in humans: Protocol for a randomized placebo-controlled trial

INTRODUCTION

Over the last 10 years, it has been demonstrated that photobiomodulation therapy (PBMT), also known as phototherapy, using low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) has ergogenic effects, improving athletic performance and also 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 an aerobic endurance training protocol.

METHODS AND ANALYZES

A randomized, triple-blind, placebo-controlled clinical trial will be carried out. Healthy male volunteers will be randomly distributed into 4 experimental groups: PBMT before and after training sessions + PBMT during detraining, PBMT before and after training sessions + placebo during detraining, placebo before and after training sessions + PBMT during detraining, and placebo before and after training sessions + placebo during detraining. The aerobic endurance training sessions will be carried out using motorized treadmills during 12 weeks, and the detraining period will consist in the next 4 weeks after that. It will be analyzed the time until exhaustion, maximal oxygen uptake (VO2max), and fat percentage of volunteers.

DISCUSSION

Despite the increasing body of evidence for the use of PBMT as an ergogenic agent, several aspects remain unknown. The findings of this study will contribute to the advance of knowledge in this field regarding clinical applications.

ETHICS AND DISSEMINATION

This study was approved by the Research Ethics Committee of Nove de Julho University. The results from this study will be further disseminated through scientific publications in international peer-reviewed journals and presentations at national and international scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03879226.

Effects of Light-Emitting Diode Therapy on the Performance of Biceps Brachii Muscle of Young Healthy Males After 8 Weeks of Strength Training: A Randomized Controlled Clinical Trial

Vieira, KVSG, Ciol, MA, Azevedo, PH, Pinfildi, CE, Renno, ACM, Colantonio, E, and Tucci, HT. Effects of light-emitting diode therapy on the performance of biceps brachii muscle of young healthy males after 8 weeks of strength training: a randomized controlled clinical trial. J Strength Cond Res 33(2): 433-442, 2019-We assessed the effect of adding light-emitting diode therapy (LEDT) to an 8-week strength training of biceps brachii in healthy young males. Forty-five participants were randomized into training plus LEDT, training plus sham LEDT, and control groups (n = 15 each). Individuals in the LEDT groups participated in strength training performed in a Scott machine at their maximum number of elbow flexion-extension repetitions. The LEDT was applied to biceps brachii of dominant limb at the end of training sessions (device "on" for LEDT and "off" for sham LEDT). Training loads were re-evaluated every 2 weeks. Controls did not receive training during 8 weeks. All groups were evaluated for 1 repetition maximum (1RM) and fatigue at baseline and 8 weeks. Additionally, the 2 LEDT groups were evaluated every 2 weeks for 1-RM and number of elbow flexion-extension repetitions. The groups were statistically different in mean difference and mean percent change of 1-RM from baseline to week 8 (p < 0.001). Analyzing the 2 LEDT groups, we found an interaction between group and time (p = 0.02), with a slightly faster increase in 1-RM for the LEDT than the sham LEDT. Over time, both groups decreased the number of repetitions of elbow flexion-extension (differences not statistically significant), possibly because of the increase of load over time. We found no difference in change of fatigue index among the 3 groups. Our study showed potential benefits to 1RM when LEDT is applied after a strength training session. Future studies might assess whether different doses of LEDT can reduce fatigue in strength training.

Effects of Laser Acupuncture on Delayed Onset Muscle Soreness of the Biceps Brachii Muscle: A Randomized Controlled Trial

Objectives

The aim of this study was to explore the effects of laser acupuncture on improvement of recovery and muscle performance in delayed muscle soreness (DOMS) when applied before exercise.

Methods

This randomized, blinded, and controlled study included healthy participants (n = 40) who were randomized into laser acupuncture and placebo groups. Laser acupuncture was applied to the Tianquan (PC2) and Chihtseh acupoints (LU5) at a dose of 36 J and energy density of 9.7 J/cm² before inducing DOMS. The placebo group received sham laser acupuncture with no laser output. Visual analog scale (VAS), proprioception, pressure pain threshold (PPT), arm circumference, and muscle strength were observed at the baseline and 24, 48, 72, and 96 h after induction of DOMS.

Results

Significant changes in the VAS (F_{4,  43.96} = 31.47; p = 0.001), PPT (F_4,  1.35 = 35.07; p = 0.001), normalized arm circumference (F_{4,  0.001} = 3.87; p = 0.005), and normalized muscle strength (F_4,  0.31 = 24.99; p = 0.001) were observed within the groups over time (p < 0.05), but there were no significant differences between the two groups (p > 0.05). Normalized arm circumference was significantly different between the two groups at 48 and 72 h after induction of DOMS (p < 0.05).

Conclusion

Photobiomodulation therapy on Tianquan (PC2) and Chihtseh acupoints (LU5) before the exercise did not significantly decrease DOMS and increase muscle performance. Laser acupuncture as a supplemental therapy seemed to have no effect on DOMS prevention.

Photobiomodulation Therapy on Physiological and Performance Parameters During Running Tests: Dose-Response Effects

Dellagrana, RA, Rossato, M, Sakugawa, RL, Baroni, BM, and Diefenthaeler, F. Photobiomodulation therapy on physiological and performance parameters during running tests: Dose-response effects. J Strength Cond Res 32(10): 2807-2815, 2018-This study was aimed at verifying effects of photobiomodulation therapy (PBMT) with different energy doses (15, 30, and 60 J per site) on physiological and performance parameters during running tests. Fifteen male recreational runners participated in a crossover, randomized, double-blind, and placebo-controlled trial. They performed testing protocol in 5 sessions with different treatments: control, placebo, and PBMT with 15, 30, or 60 J per site (14 sites in each lower limb). Physiological and performance variables were assessed during submaximal (at 8 and 9 km·h) and maximal running tests. Photobiomodulation therapy with 30 J significantly improved running economy (RE) at 8 and 9 km·h (3.01%, p=0.008 and 3.03%, p=0.009, respectively), rate of perceived exertion (RPE) at 8 km/h21 (7.86%, p=0.033), velocity at V[Combining Dot Above]O2max (3.07%, p= 0.029), peak of velocity (PV) (1.49%, p=0.035), and total time to exhaustion (TTE) (3.41%, p=0.036) compared with placebo. Photobiomodulation therapy with 15 J improved running economy at 9 km/h21 (2.98%, p=0.025), rate of perceived exertion at 8 km/h21 (4.80%, p=0.010), PV (1.33%, p=0.008), total time to exhaustion (3.06%, p=0.008), and total distance (4.01%, p=0.011) compared with the placebo; whereas PBMT with 60 J only increased RE at 9 km/h21 (3.87%, p=0.024) compared with placebo. All PBMT doses positively affected physiological and/or performance parameters; however, magnitude-based inference reported that PBMT applied with 30 J led to more beneficial effects than 15 and 60 J.

Immediate effects of photobiomodulation with low-level laser therapy on muscle performance: an integrative literature review

ABSTRACT Purpose: to analyze the influence of low-level laser on muscle performance and to identify the most used dosimetric parameters. Methods: the search for articles was carried out on the PubMed, BVS, Web of Science and SciELO platforms. The articles selected were original ones, with available abstracts and that evaluated the use of photobiomodulation on muscular performance. The data were analyzed according to the author, year of publication, sample, place of application, parameters evaluated, wavelength, dosimetry used and results found. Results: the final sample consisted of 27 articles published between 2008 and 2017. The sample size in the studies ranged from 8 to 60 individuals, aged from 17 to 70 years. A greater use of infrared wavelength, with punctual applications carried out in the path of the muscle, was observed. Regarding the dose, there was a variation from 0.24 to 50 joules per point. Of the total, only 5 (18.5%) studies had not found significant answers for the considered variables. Conclusion: most of the studies pointed out that low-level laser can improve muscle performance. The methodology used in the work was diversified, rendering data compilation difficult, being impossible to set the ideal parameters for this purpose.

Clinical and scientific recommendations for the use of photobiomodulation therapy in exercise performance enhancement and post-exercise recovery: current evidence and future directions

BACKGROUND

There is about ten years since the first randomized controlled trial looking for the effects of photobiomodulation therapy using low-level laser therapy and/or light emitting diodes therapy in athletic performance enhancement was published. Since then, the knowledge in this field has increasing exponentially.

OBJECTIVE

Given the fast advance in clinical interest, research and development in the use of photobiomodulation therapy for athletic performance enhancement and also to accelerate post-exercise recovery, as pioneers in this research field we felt the need to establish recommendations to ensure the correct use of the therapy, and also to guide the further studies in this area looking for the achievement of highest scientific evidence. It is important to highlight that the establishment of both clinical and scientific recommendations in this masterclass article were based on the most recent systematic reviews with meta-analysis and randomized controlled trials published in this field. It is important to stress that the recommendations of this masterclass article are based on most recent systematic reviews with meta-analysis and RCTs published in this research field. Future guidelines must follow the same direction and must be based only at the highest scientific evidence, avoiding overstatements and extrapolations based on animal experiments and case-studies.

Photobiomodulation therapy before futsal matches improves the staying time of athletes in the court and accelerates post-exercise recovery

This study aimed to analyze PBMT effects on futsal player's performance and recovery in a non-controlled field environment. It is a randomized, triple-blinded, placebo-controlled, crossover clinical trial. The research included six professional athletes and in each match phototherapy treatments were performed before matches (40 minutes), blood samples were collected before treatments, and samples immediately after the end of the matches and 48 h after. Furthermore, videos were analyzed to quantify the time athletes spent on the pitch and the distance they covered. PBMT was performed at 17 sites of each lower limb (40 mins before matches), employing a cluster with 12 diodes (4 laser diodes of 905 nm, 4 LEDs of 875 nm, and 4 LEDs of 640 nm, 30 J per site). The performance of the athlete could be quantified considering the time on the pitch and the distance covered; the biochemical markers evaluated were creatine kinase, lactate dehydrogenase, blood lactate, and oxidative damage to lipids and proteins. PBMT significantly increased the time of staying in the pitch and a significant improvement in all the biochemical markers evaluated. No statistically significant difference was found for the distance covered. Pre-exercise PBMT can enhance performance and accelerate recovery of high-level futsal players.

Near-infrared laser-mediated drug release and antibacterial activity of gold nanorod-sputtered titania nanotubes

The infection control of implants is one of the hot issues in the field of medicine and dentistry. In this study, we prepared gold nanorod–sputtered titania nanotubes on titanium surface, which is the main component of implant material, and aimed to estimate the remote-controlled tetracycline release and resulting antibacterial effects of gold nanorod–sputtered titania nanotubes using near-infrared laser irradiation. Gold nanorods prepared by ion plasma sputtering (aspect ratio = 1:3) showed optical properties like those of chemically synthesized gold nanorods, exhibiting photothermal effects in the near-infrared region, as demonstrated using field-emission scanning electron microscopy, transmission electron microscopy, and diffuse ultraviolet–visible–near-infrared spectrophotometry. In addition, a 2 wt% tetracycline/polycaprolactone mixture was found to be the most suitable experimental group to demonstrate the biological compatibilities and antibacterial activities. The results of antibacterial agar diffusion tests and near-infrared-mediated tetracycline release tests in vivo confirmed that remote-controlled tetracycline elution using near-infrared laser irradiation was highly effective. Therefore, gold nanorod–sputtered titania nanotubes would be expected to enable the continued use of the photothermal therapy of gold nanorods and extend the limited use of titania showing photocatalytic activity only within the ultraviolet-to-near-infrared region.

Photobiomodulation and physical exercise on strength, balance and functionality of elderly women

Abstract Introduction: Aging is associated with structural changes in muscle tissue, which leads to the loss of functional independence. The preservation of the muscle strength through strength training, and recently, low-level laser therapy (LLLT), has high clinical significance. Objective: to investigate the effects of photobiomodulation (PBM - 808 nm, 100 mW, 35.7 W/cm2 and 7 J) associated with a strength training program on quadriceps muscle strength, balance and functional capacity in elderly women. Methods: Thirty-five healthy women between 60 to 70 years old were divided into two groups: Placebo Group (n = 13) and Active Group (n = 14). The exercise protocol consisted of knee flexion-extension exercise followed by application of PBM placebo or active, twice a week for 8 consecutive weeks. Results: showed a significant increase in 6MWT (p = 0.001), SPPB (p = 0.006) and 1-MR (p = 0.001) in both groups. The strength training program associated with PBM active improved a significant increase, relative to baseline, to the right medial/lateral stability index (p = 0.007) and decrease in the Fall Risk Test (p = 0.005). Conclusion: the strength training produced a significant increase of muscle strength and functionality and when combined with the PMB it was significant in the improvement of postural stability and decrease of fall risk.

Acute Effects of Low-Level Laser Therapy on Patients' Functional Capacity in the Postoperative Period of Coronary Artery Bypass Graft Surgery: A Randomized, Crossover, Placebo-Controlled Trial

OBJECTIVE

The aim of this study was to evaluate the acute effects of low-level laser therapy (LLLT) on the functional capacity to exercise tested by incremental shuttle walking test (ISWT) after coronary artery bypass graft (CABG) surgery.

METHODS

Fifteen male patients (60 ± 9 years) were crossed over during the experiment, to compare the outcomes after active LLLT and placebo LLLT treatments. LLLT (850 nm, 200 mW, 30 J to each point, resulting in a total of 240 J per quadriceps muscle), using a multidiode cluster (five spots; 6 J/spot) in eight points per leg was performed 3 min before the ISWT. We analyzed distance walked, Borg scale of perceived exertion, heart rate, and brachial arterial blood pressure. Markers of tissue damage [lactate dehydrogenase (LDH)] and oxidative stress [lipid peroxidation, total thiol levels, and antioxidant enzyme activity of superoxide dismutase (SOD) and catalase (CAT)] were also measured in peripheral blood.

RESULTS

Comparison of the distances walked revealed no significant differences between the LLLT and placebo LLLT groups (p = 0.779). Regarding the Borg scale (p = 0.567), heart rate (p = 0.506) as well as systolic and diastolic blood pressure (p = 0.164 and p = 0.140, respectively), no differences were observed between LLLT and placebo LLLT groups. Application of LLLT was not able to change levels of LDH (p = 0.214), oxidative lipid damage (p = 0.733), total thiol levels (p = 0.925), SOD (p = 0.202), and CAT (p = 0.825) enzyme activities.

CONCLUSIONS

Acute LLLT improved neither functional capacity to exercise nor the markers of oxidation after CABG.

TRIAL REGISTRATION

Registered as a clinical trial (NCT02688426).

Photobiomodulation (PBM) therapy at 904 nm mitigates effects of exercise-induced skeletal muscle fatigue in young women

Muscle fatigue is a process influenced by several mechanisms such as concentration of metabolic substrates, changes in blood flow, and increases in reactive oxygen species that impair contractile muscle function. In this context, photobiomodulation has been investigated for preventing muscle fatigue, with reports of positive effects on muscle performance. This study aimed to investigate the effects of 904-nm LASER photobiomodulation on rectus femoris muscle performance in young women. Eighteen young women participated in a randomized, participant and assessor-blinded crossover trial with placebo control. Active LASER (904 nm, 60 mW, 250 Hz, 3.6 J per diode, total dose of 129.6 J) intervention was applied prior to an isokinetic fatigue protocol consisting of a set of 60 concentric quadricep contractions at a constant dynamometer angular velocity of 180°/s. Compared to placebo, LASER photobiomodulation significantly reduced muscle fatigue across a range of indicators including reduced ratings of perceived exertion (P = 0.0139), and increased electromyographic fatigue index (EFI) (P = 0.005). The isokinetic dynamometer performance analysis demonstrated that LASER photobiomodulation increased peak torque (P = 0.04), time to peak torque (P = 0.042), total work (P = 0.032), average power (P = 0.0007), and average peak torque (P = 0.019) between both experimental conditions. No significant difference was observed for work fatigue index (P = 0.29) or for lactate concentration (P > 0.05). Photobiomodulation at 904 nm was effective in reducing fatigue levels and increasing muscle performance in young active women but had no effect on lactate levels.

Improvement of Performance and Reduction of Fatigue With Low-Level Laser Therapy in Competitive Cyclists

Evidence indicates that low-level laser therapy (LLLT) minimizes fatigue effects on muscle performance. However, the ideal LLLT dosage to improve athletes'performance during sports activities such as cycling is still unclear. Therefore, the goal of this study was to investigate the effects of different LLLT dosages on cyclists'performance in time-to-exhaustion tests. In addition, the effects of LLLT on the frequency content of the EMG signals to assess fatigue mechanisms were examined. Twenty male competitive cyclists participated in a crossover, randomized, double-blind, placebo-controlled trial. They performed an incremental cycling test to exhaustion (on day 1) followed by 4 time-to-exhaustion tests (on days 2-5) at their individual maximal power output. Before each time-to-exhaustion test, different dosages of LLLT (135, 270, and 405 J/thigh, respectively) or placebo were applied at the quadriceps muscle bilaterally. Power output and muscle activation from both lower limbs were recorded throughout the tests. Increased performance in time-to-exhaustion tests was observed with the LLLT-135 J (∼22 s; P < .01), LLLT-270 J (∼13 s; P = .03), and LLLT-405 J (∼13 s; P = .02) compared to placebo (149 ± 23 s). Although LLLT-270 J and LLLT-405 J did not show significant differences in muscle activation compared with placebo, LLLT-135 J led to an increased high-frequency content compared with placebo in both limbs at the end of the exhaustion test (P ≤ .03). In conclusion, LLLT increased time to exhaustion in competitive cyclists, suggesting this intervention as a possible nonpharmacological ergogenic agent in cycling. Among the different dosages, LLLT-135 J seems to promote the best effects.

EFEITO AGUDO DO LASER DE BAIXA POTÊNCIA NA FADIGA DO BÍCEPS BRAQUIAL DE ATLETAS DE VOLEIBOL

RESUMO Introdução: A laserterapia de baixa potência tem entre seus propósitos auxiliar a recuperação de tecidos biológicos, atenuando os efeitos da fadiga muscular e contribuindo com a melhora do desempenho em atletas. Aspectos metodológicos ainda limitam as conclusões do efeito agudo da laserterapia sobre o desempenho muscular. Objetivo: Verificar o efeito agudo do laser terapêutico de baixa potência na fadiga induzida do bíceps braquial de atletas de voleibol. Métodos: Este foi um estudo randomizado e duplo-cego, aprovado pelo Comitê de Ética da UNESP de Marília. Participaram do estudo 19 atletas de voleibol de ambos os sexos. Realizou-se coleta de dados eletromiográficos do músculo bíceps braquial no exercício isométrico de flexão de cotovelo antes e após a aplicação do laser terapêutico. Um haltere com 75% do pico de força, obtido por uma célula de carga, foi utilizado para o protocolo de fadiga. Em seguida, os voluntários foram submetidos à aplicação do laser (ativo ou placebo) em seis pontos do músculo bíceps braquial. Os dados eletromiográficos foram analisados no domínio da frequência, utilizando-se o software Myosystem®. Verificou-se a distribuição de normalidade dos dados pelo teste de Shapiro-Wilk, e utilizou-se Anova (split plot) de medidas repetidas a fim de testar a interação entre tempo e grupo. Resultados: Para nenhuma das variáveis analisadas foi observada interação significativa entre grupo e tempo, indicando que o grupo irradiado não apresentou vantagens com relação ao grupo placebo. Conclusão: Após o protocolo de fadiga proposto, uma única aplicação de laser de baixa potência não foi suficiente para produzir efeitos positivos no desempenho de força e no sinal eletromiográfico do músculo bíceps braquial de atletas de voleibol.

When is the best moment to apply photobiomodulation therapy (PBMT) when associated to a treadmill endurance-training program? A randomized, triple-blinded, placebo-controlled clinical trial

Photobiomodulation therapy (PBMT) employing low-level laser therapy (LLLT) and/or light emitting diode therapy (LEDT) has emerged as an electrophysical intervention that could be associated with aerobic training to enhance beneficial effects of aerobic exercise. However, the best moment to perform irradiation with PBMT in aerobic training has not been elucidated. The aim of this study was to assess the effects of PBMT applied before and/or after each training session and to evaluate outcomes of the endurance-training program associated with PBMT. Seventy-seven healthy volunteers completed the treadmill-training protocol performed for 12 weeks, with 3 sessions per week. PBMT was performed before and/or after each training session (17 sites on each lower limb, using a cluster of 12 diodes: 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs, dose of 30 J per site). Volunteers were randomized in four groups according to the treatment they would receive before and after each training session: PBMT before + PBMT after, PBMT before + placebo after, placebo before + PBMT after, and placebo before + placebo after. Assessments were performed before the start of the protocol and after 4, 8, and 12 weeks of training. Primary outcome was time until exhaustion; secondary outcome measures were oxygen uptake and body fat. PBMT applied before and after aerobic exercise training sessions (PBMT before + PBMT after group) significantly increased (p < 0.05) the percentage of change of time until exhaustion and oxygen uptake compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 4th, 8th, and 12th week. PBMT applied before and after aerobic exercise training sessions (PBMT before + PBMT after group) also significantly improved (p < 0.05) the percentage of change of body fat compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 8th and 12th week. PBMT applied before and after sessions of aerobic training during 12 weeks can increase the time-to-exhaustion and oxygen uptake and also decrease the body fat in healthy volunteers when compared to placebo irradiation before and after exercise sessions. Our outcomes show that PBMT applied before and after endurance-training exercise sessions lead to improvement of endurance three times faster than exercise only.

Cardiac autonomic responses and number of repetitions maximum after LED irradiation in the ipsilateral and contralateral lower limb

The aim of this study was to verify the maximum number of repetitions, fatigue index, blood lactate concentration ([Lac]), and cardiac autonomic responses after LED irradiation (LEDI) in the ipsilateral and contralateral limb. Twelve male subjects (22.0 ± 3.86 years; weight 82.94 ± 12.58 kg; height 1.77 ± 0.05 m), physically active, took part in this study. The subjects underwent a one repetition maximum (1RM) test and performed four randomly experimental sessions in the horizontal leg press exercise, which consisted in four sets of maximum repetitions at 80% of 1RM. The subjects performed two experimental sessions applying LED active or placebo on ipsilateral limb and two experimental sessions applying LED active or placebo on contralateral limb prior exercise and in the interval of sets on quadriceps and hamstrings muscles. A number of repetitions and fatigue index were verified. [Lac] and heart rate variability (HRV) were collected during post-exercise recovery and analyzed. It was observed that active LEDI promoted an increase in maximal number of repetitions (LEDI = 44.4 ± 9.0 vs placebo = 39.9 ± 11.4; p < 0.05) and decreases the fatigue index (LEDI = 34.3 ± 21.8% vs placebo = 50.0 ± 26.6%; p < 0.05) comparing to placebo situation, only in the ipsilateral application. There were no differences on [Lac] and in HRV parameters comparing LEDI vs placebo on post-exercise recovery in both applications (p > 0.05). The LEDI improves performance only in the ipsilateral application, but there were no differences on [Lac] and cardiac autonomic responses after exercise for both the applications.

Photobiomodulation therapy for the improvement of muscular performance and reduction of muscular fatigue associated with exercise in healthy people: a systematic review and meta-analysis

Researches have been performed to investigate the effects of phototherapy on improving performance and reduction of muscular fatigue. However, a great variability in the light parameters and protocols of the trials are a concern to establish the efficacy of this therapy to be used in sports or clinic. The aim of this study is to investigate the effectiveness, moment of application of phototherapy within an exercise protocol, and which are the parameters optimally effective for the improvement of muscular performance and the reduction of muscular fatigue in healthy people. Systematic searches of PubMed, PEDro, Cochrane Library, EMBASE, and Web of Science databases were conducted for randomized clinical trials to March 2017. Analyses of risk of bias and quality of evidence of the included trials were performed, and authors were contacted to obtain any missing or unclear information. We included 39 trials (861 participants). Data were reported descriptively through tables, and 28 trials were included in meta-analysis comparing outcomes to placebo. Meta-analysis was performed for the variables: time until reach exhaustion, number of repetitions, isometric peak torque, and blood lactate levels showing a very low to moderate quality of evidence and some effect in favor to phototherapy. Further investigation is required due the lack of methodological quality, small sample size, great variability of exercise protocols, and phototherapy parameters. In general, positive results were found using both low-level laser therapy and light-emitting diode therapy or combination of both in a wavelength range from 655 to 950 nm. Most of positive results were observed with an energy dose range from 20 to 60 J for small muscular groups and 60 to 300 J for large muscular groups and maximal power output of 200 mW per diode.

Effects of photobiomodulation therapy and topical non-steroidal anti-inflammatory drug on skeletal muscle injury induced by contusion in rats-part 2: biochemical aspects

Muscle injuries trigger an inflammatory process, releasing important biochemical markers for tissue regeneration. The use of non-steroidal anti-inflammatory drugs (NSAIDs) is the treatment of choice to promote pain relief due to muscle injury. NSAIDs exhibit several adverse effects and their efficacy is questionable. Photobiomodulation therapy (PBMT) has been demonstrated to effectively modulate inflammation induced from musculoskeletal disorders and may be used as an alternative to NSAIDs. Here, we assessed and compared the effects of different doses of PBMT and topical NSAIDs on biochemical parameters during an acute inflammatory process triggered by a controlled model of contusion-induced musculoskeletal injury in rats. Muscle injury was induced by trauma to the anterior tibial muscle of rats. After 1 h, rats were treated with PBMT (830 nm, continuous mode, 100 mW of power, 35.71 W/cm²; 1, 3, and 9 J; 10, 30, and 90 s) or diclofenac sodium (1 g). Our results demonstrated that PBMT, 1 J (35.7 J/cm²), 3 J (107.1 J/cm²), and 9 J (321.4 J/cm²) reduced the expression of tumor necrosis factor alpha (TNF-α) and cyclooxygenase-2 (COX-2) genes at all assessed times as compared to the injury and diclofenac groups (p < 0.05). The diclofenac group showed reduced levels of COX-2 only in relation to the injury group (p < 0.05). COX-2 protein expression remained unchanged with all therapies except with PBMT at a 3-J dose at 12 h (p < 0.05 compared to the injury group). In addition, PBMT (1, 3, and 9 J) effectively reduced levels of cytokines TNF-α, interleukin (IL)-1β, and IL-6 at all assessed times as compared to the injury and diclofenac groups (p < 0.05). Thus, PBMT at a 3-J dose was more effective than other doses of PBMT and topical NSAIDs in the modulation of the inflammatory process caused by muscle contusion injuries.