Effect of 808 nm low-level laser therapy in exercise-induced skeletal muscle fatigue in elderly women

Influence of photobiomodulation therapy on the physical performance of women during the follicular phase of the menstrual cycle: A double-blind Sham-controlled randomized clinical trial

To evaluate the effects of photobiomodulation on the physical performance of healthy women, considering the menstrual cycle. 27 physically active healthy women (age 25.68 ± 3.99 years; mass 63.76 ± 12.77 kg; height 1.65 ± 0.59 cm) during the initial follicular phase (FF1 and FF2) of the menstrual cycle underwent performance evaluations, through a supramaximal test, subjective perception of exertion, blood lactate, and evaluations in the isokinetic dynamometer. Photobiomodulation (PBM) (200J) and Sham (0J) therapy were applied 10 min before the performance evaluations on the quadriceps femoris, hamstrings, and triceps surae muscles. A significance level of 5% was adopted and the effect size was calculated by Cohen's d. It was not possible to observe a significant difference (p > 0.05) in any of the performance variables evaluated in the comparison between groups, only small effects for total distance, final subjective perception of exertion, lactate peak and lactate delta in the PBM group. PBM did not improve muscle performance, resistance to fatigue, perceived exertion, and blood lactate concentrations during a predominantly anaerobic test in healthy women during the FF of the menstrual cycle.

Effects of the association of different volumes of strength training with photobiomodulation therapy on insulin resistance: A protocol for a randomized, triple-blind, placebo-controlled trial

Background

Insulin resistance (IR) is the main risk factor for developing type 2 diabetes. Both strength training (ST) and photobiomodulation therapy (PBMt) reduce IR, but the effect of combining different volumes of ST with PBMt is unknown.

Methods

Overweight/obese individuals will be assigned to 4 groups (n = 12/group): ST with volume following international guidelines (3 sets per exercise - high volume) or one-third of this volume (1 set per exercise - low volume), combined with PBMt or placebo. ST will be performed for 20 sessions over 10 weeks and will consist of 7 exercises. The PBMt will be applied after training sessions using blankets with light emitters (LEDs) placed over the skin on the frontal and the posterior region of the body, following the parameters recommended by the literature. The placebo group will undergo an identical procedure, but blankets will emit insignificant light. To measure plasma glucose and insulin concentrations, oral glucose tolerance tests (OGTT) will be performed before and after the training period. Thereafter, IR, the area under the curve of glucose and insulin, and OGTT-derived indices of insulin sensitivity/resistance will be calculated.

Expected impact on the field

This study will determine the effects of different ST volumes on IR and whether the addition of PBMt potentiates the effects of ST. Because previously sedentary, obese, insulin-resistant individuals might not comply with recommended volumes of exercise, the possibility that adding PBMt to low-volume ST enhances ST effects on IR bears practical significance.

Immediate effects of photobiomodulation on maximum lip pressure

PURPOSE

To verify the immediate effects of different doses of photobiomodulation on maximum lip pressure.

METHODS

Experimental, randomized and triple-blind study. The sample consisted of 23 women and 17 men, age between 18 and 33 years old (average 23.18 years old, SD=2.1), distributed in four groups: CG (control group), G1, G4 and G7. The maximum pressure was assessed with the Iowa Oral Performance Instrument (IOPI). The bulb was placed between the lips and the participants were instructed to press it as strong as possible. Infrared LASER (808 nm), manufactured by DMC, Therapy EC model, 100 mW of power output, was applied. The doses tested were 1 J (G1), 4 J (G4) and 7 J (G7), applied at six points of the orbicularis oris muscle. In the CG there was no intervention. The evaluation procedures were repeated after the LASER application. The results were analyzed with a significance level of 95%.

RESULTS

The maximum lip pressure increased significantly only in the group irradiated with 7 J.

CONCLUSION

Low level LASER therapy with 7 J dose promoted changes in the performance of the orbicularis oris muscle in the maximum pressure task.

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.

Effect of photobiomodulation in the patellofemoral pain syndrome; randomized clinical trial in young women

OBJECTIVE

patellofemoral pain syndrome (PFPS) is one of the most frequent musculoskeletal disorders in the knee joint, affecting mainly physically active adolescents and young adults; its main symptom is pain. Physiotherapy has several therapeutic modalities aimed at pain relief, among which are photobiomodulation (PBM). The aim of the study was to analyze the effects of using PBM in cluster form (Laser + LED) in patients with PFPS.

PATIENTS AND METHODS

This study is characterized as quantitative, experimental, randomized, composed of 30 women with PFPS, randomized into two groups: Control Group (CG) and PBM Group (PBMG). Both groups underwent three evaluations: pre-intervention, post-intervention, and after one month of follow-up. Participants of the PBMG were presented to the application of the cluster device, three times a week, for four weeks. The intensity of spontaneous pain and movement were evaluated, knee function tests and function questionnaires. The results showed a reduction in pain only for the landing of the jump. As for the other variables there was no interaction of factors; the questionnaires used showed larger effect sizes for PBMG when compared to CG. It is possible to conclude that the use of PBM showed benefit in reducing pain at the time of landing of the jump and functional assessment questionnaires.

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.

Dose-Response Effect of Photobiomodulation Therapy on Muscle Performance and Fatigue During a Multiple-Set Knee Extension Exercise: A Randomized, Crossover, Double-Blind Placebo-Controlled Trial

Objective: The aim of this study was to identify the best energy dose of photobiomodulation therapy (PBMT) able to improve muscle performance and reduce fatigue during multiple-set knee extension exercise. Methods: Eighteen physically active men participated in this study. Each participant performed an isokinetic exercise protocol (5 sets of 10 knee extension repetitions, maximum contractions at 60°·s^-1) in 6 sessions, 1 week apart. Control condition (no PBMT/placebo treatments) was applied at the first and sixth sessions. Placebo or PBMT with 135, 270, or 540 J/quadriceps was randomly applied from the second to fifth sessions. Placebo/PBMT treatments were always applied at two moments: 6 h before and immediately before exercise. The isometric and isokinetic concentric peak torques were assessed before and after the exercise protocol. Results: The knee extension exercise performance (total work performed during exercise) was not affected by PBMT (135, 270, and 540 J) compared with placebo treatment. However, all PBMT treatments (135, 270, and 540 J) led to lower percentage drop compared with placebo and control conditions on isometric peak torque (IPT), concentric peak torque (CPT), and concentric work (W). All PBMT doses led to possibly positive or likely positive effects on IPT, CPT, and W compared with placebo. Conclusions: Our findings demonstrate that PBMT with 135, 270, and 540 J applied at two moments (6 h before and immediately before exercise) was able to produce the same total work with lower fatigue, which may facilitate the performance of additional sets (i.e., higher training volume).

Photobiomodulation Therapy Modulates Muscle Gene Expression and Improves Performance of Rats Subjected to a Chronic Resistance Exercise Protocol

Objective: In professional sports activities, the search for increased performance is constant. Electrophysical agents, including photobiomodulation (PBM), have been used in the sports context to accelerate postworkout recovery, prevent injuries, and even to improve performance. This study aims to investigate the effects of infrared laser (904 nm) on skeletal muscle gene expression of performance-related proteins of rats submitted to a chronic resistance training protocol. Materials and methods: Male Wistar rats (n = 40), weighing ±300 g were divided into four groups: sedentary control (CT, n = 10); irradiated control (CTL, n = 10); exercised not irradiated (EX, n = 10); exercised irradiated (EXL, n = 10). To assess the performance, the maximum carrying test was adapted and applied 72 h prior the training and 72 h after the last exercise session. The vertical weight climbing protocol was adapted for resistance training 3 × per week with 48 h interval between each session: first week adaptation, second week 25% of body weight (BW), third week 50% BW, fourth week 75% BW, and fifth week 100% BW. Animals were irradiated before exercise on hind paws 50 sec each, with infrared laser 904 nm 5 days per week, during 4 weeks, 9 J per leg in a total of 18 J energy per day. Results: The EXL performed more climbing (7.1 ± 0.91) compared to EX (4.4 ± 0.63). PBM promoted increased expression of lactate dehydrogenase enzyme, mammalian target of rapamycin protein, and androgen receptor (p < 0.05) but not the myosin heavy chain (p = 0.43). Conclusions: PBM therapy increases the expression of performance-related muscle mass gain genes besides improving the resistance training performance.

Acute application of photobiomodulation does not bring important gains for the muscular performance and functionality of diabetic individuals

Photobiomodulation therapy (PBMT) has been used to improve the physical performance of individuals with advanced age; however, there are no studies in the literature that support the application of light-emitting diode (LED) therapy for the muscular performance of individuals with diabetes mellitus who show a decline in functionality. The aim of the study was to analyze the acute effects of PBMT on strength and functional performance in type 2 diabetic individuals. Sixty-three volunteers were recruited and randomized into five groups: control (C), sham (S), red LED (R), infrared LED (IR), and red LED + infrared LED (R + IR). On the first day, the volunteers were evaluated using the time up and go (TUG), the 6-min walk test (6MWT), and isokinetic dynamometer of the ankle. In the following 3 days, groups R, IR, R + IR, and S returned for application of PBMT bilaterally, with 180 J of energy on each leg. On the fifth day, a reassessment was performed. There was no statistical difference between groups for the variables of the isokinetic dynamometer, TUG, and 6MWT. Analysis of the size of the clinical effect for the isokinetic variables showed that there was no pattern among the effects observed. There is a moderate effect in favor of R, IR, and R + IR in relation to C for the TUG and a moderate effect of R + IR in relation to C for the 6MWT. The PBMT applied for a short period does not bring important gains for the muscular performance and functionality of diabetic individuals.

Effects of photobiomodulation on muscle strength in post-menopausal women submitted to a resistance training program

The aim of this study was to compare the effects of resistance training of low volume and high intensity with or without photobiomodulation (PBM) on muscle strength and functional performance in post-menopausal women. Thirty-four post-menopausal women were randomized into resistance training (RTG, n = 17) or resistance training plus PBM (PBMG, n = 17). Individuals from both groups received the same RT protocol consisting of leg-press 45°, front lat pulldown, leg curl, chest press, and squat performed in two sets of 10 repetitions with a workload of 75% of one repetition maximum (1RM), twice per week, during 8 weeks. PBMG individuals also received, prior to the exercise session, PBM through a cluster containing 7 visible diodes (630 nm) and 7 infrared diodes (850 nm) with power of 100 mW each and energy of 4 J per diode, applied to the quadriceps femoris muscle; individuals from RTG received placebo PBM prior to the sessions, applied with the same device switched off. Muscle strength (1RM; isometric dynamometer), functional performance (Time Up and Go; Berg Balance Scale; 6-min walk test), and quality of life (World Health Organization Quality of Life-Bref) were performed before and after 8 weeks. Both groups increased muscle strength (p < 0.001) for all exercises, without group differences (p = 0.651). Quality of life (p = 0.015) and balance (p = 0.006) increased only in the RTG. The results suggest that PBM were not able for inducing additional benefits to RT to improve muscle strength in post-menopausal women.

Infrared Low-Level Laser Therapy (Photobiomodulation Therapy) before Intense Progressive Running Test of High-Level Soccer Players: Effects on Functional, Muscle Damage, Inflammatory, and Oxidative Stress Markers-A Randomized Controlled Trial

The effects of preexercise photobiomodulation therapy (PBMT) to enhance performance, accelerate recovery, and attenuate exercise-induced oxidative stress were still not fully investigated, especially in high-level athletes. The aim of this study was to evaluate the effects of PBMT (using infrared low-level laser therapy) applied before a progressive running test on functional aspects, muscle damage, and inflammatory and oxidative stress markers in high-level soccer players. A randomized, triple-blind, placebo-controlled crossover trial was performed. Twenty-two high-level male soccer players from the same team were recruited and treated with active PBMT and placebo. The order of interventions was randomized. Immediately after the application of active PBMT or placebo, the volunteers performed a standardized high-intensity progressive running test (ergospirometry test) until exhaustion. We analyzed rates of oxygen uptake (VO_{2 max}), time until exhaustion, and aerobic and anaerobic threshold during the intense progressive running test. Creatine kinase (CK) and lactate dehydrogenase (LDH) activities, levels of interleukin-1β (IL-1-β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), levels of thiobarbituric acid (TBARS) and carbonylated proteins, and catalase (CAT) and superoxide dismutase (SOD) activities were measured before and five minutes after the end of the test. PBMT increased the VO_{2 max} (both relative and absolute values—p < 0.0467 and p < 0.0013, respectively), time until exhaustion (p < 0.0043), time (p < 0.0007) and volume (p < 0.0355) in which anaerobic threshold happened, and volume in which aerobic threshold happened (p < 0.0068). Moreover, PBMT decreased CK (p < 0.0001) and LDH (p < 0.0001) activities. Regarding the cytokines, PBMT decreased only IL-6 (p < 0.0001). Finally, PBMT decreased TBARS (p < 0.0001) and carbonylated protein levels (p < 0.01) and increased SOD (p < 0.0001)and CAT (p < 0.0001) activities. The findings of this study demonstrate that preexercise PBMT acts on different functional aspects and biochemical markers. Moreover, preexercise PBMT seems to play an important antioxidant effect, decreasing exercise-induced oxidative stress and consequently enhancing athletic performance and improving postexercise recovery. This trial is registered with Clinicaltrials.gov NCT03803956.

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.

Time Response of Photobiomodulation Therapy on Muscular Fatigue in Humans

Rossato, M, Dellagrana, RA, Sakugawa, RL, Lazzari, CD, Baroni, BM, and Diefenthaeler, F. Time response of photobiomodulation therapy on muscular fatigue in humans. J Strength Cond Res 32(11): 3285-3293, 2018-The aim of this study was to identify the effects of 2 different time responses on fatigue of knee extensor. Sixteen male volunteers (26 ± 6.0 years, 81 ± 12 kg, and 181 ± 7.4 cm) participated in the study. Participants performed the same protocol in 5 sessions {control, placebo (placebo applied both 6 hours before and immediately before the test), 6 hours before + immediately before (photobiomodulation therapy [PBMT] applied both 6 hours before and immediately before the test), 6 hours before (PBMT applied 6 hours before and placebo applied immediately before the test), and immediately before (placebo applied 6 hours before and PBMT applied immediately before the test)}. Photobiomodulation therapy was applied on knee extensor (9 sites; 30 J per site). Maximal isometric voluntary contraction (MIVC) was assessed before and after an isokinetic fatigue (45 flexion-extension concentric at 180°·s), associated with electromyography (root mean square [RMS] and median of frequency [MF]). For MIVC, there was no treatment × time interaction for all variables. Time effect was observed for peak torque (PT), RMS, and MF. Treatment effect was verified for PT, and 6 hours before + immediately before condition presented higher PT during MIVCpre than control (p = 0.004) and placebo (p = 0.044). The immediately before presented higher PT values than control (p = 0.047). Regarding MIVCpost, the PT for 6 hours before + immediately before presented higher values than control (p = 0.001) and placebo (p = 0.004). Peak torque during MIVC (pre to post) was reduced in 6 hours before + immediately before treatment (26%) compared with control (33%), placebo (29%), and immediately before (32%). The application of PBMT 6 hours + immediately before and immediately before exercise protocol is able to reduce the fatigue.

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.

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.

Surface electromyography after lower level laser therapy application on skeletal muscles in individuals with heart failure

The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) applied before a fatigue protocol through the effects on the electrical activation in the quadriceps muscle in patients with HF. Fourteen patients with the diagnosis of heart failure (HF) were selected for this double-blind, crossover type clinical trial. These participants have attended to a familiarization, LLLT, and placebo sessions, totaling three visits. The LLLT was applied in the quadriceps muscle (850 nm, 5 J per diode). The fatigue protocol consisted of concentric and eccentric isokinetic contractions (cc/ec) until exhaustion or up to 50 cc/ec. The muscular fatigue was evaluated with surface electromyography, by the analysis of integral, median frequency, and entropy. Only one application of LLLT is not able to decrease skeletal muscle activation in patients with HF. There was no reduction of muscle fatigue among the proposed protocols. Single LLLT session has no effect on the reduction of skeletal muscle fatigue in patients with HF.

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.

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.

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.

Dose-response effect of photobiomodulation therapy on neuromuscular economy during submaximal running

The purpose of this study was to verify the photobiomodulation therapy (PBMT) effects with different doses on neuromuscular economy during submaximal running tests. Eighteen male recreational runners participate in a randomized, double-blind, and placebo-controlled trial, which each participant was submitted to the same testing protocol in five conditions: control, placebo, and PBMT with doses of 15, 30, and 60 J per site (14 sites in each lower limb). The submaximal running was performed at 8 and 9 km h^-1 during 5 min for each velocity. Muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), and gastrocnemius lateralis (GL) was collected during the last minute of each running test. The root mean square (RMS) was normalized by maximal isometric voluntary contraction (MIVC) performed a priori in an isokinetic dynamometer. The RMS sum of all muscles (RMS_LEG) was considered as main neuromuscular economy parameter. PBMT with doses of 15, 30, and 60 J per site [33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm)] or placebo applications occurred before running tests. For the statistical analysis, the effect size was calculated. Moreover, a qualitative inference was used to determine the magnitude of differences between groups. Peak torque and RMS during MIVCs showed small effect sizes. According to magnitude-based inference, PBMT with dose of 15 J per site showed possibly and likely beneficial effects on neuromuscular economy during running at 8 and 9 km h^-1, respectively. On other hand, PBMT with doses of 30 and 60 J per site showed possible beneficial effects only during running at 9 km h^-1. We concluded that PBMT improve neuromuscular economy and the best PBMT dose was 15 J per site (total dose of 420 J).

Effect of Low-Level Laser Therapy and Strength Training Protocol on Hand Grip by Dynamometry

Introduction: The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) - 660 nm and 904 nm - before grip strength protocol in healthy subjects. Methods: The study included 45 healthy volunteers with an average age of 22.7 (±1.4) years, subdivided into the following groups, control group: grip strength training associated with placebo LLLT; 660 nm group: LLLT (660 nm, 20 J/cm², power of 30 mW, and beam area of 0.06 cm², continuous, energy 1.2 J, and exposure time 40 seconds per point) before grip strength training and 904 nm group: LLLT (904 nm, 10 J/cm², peak power of 70 W and 0.13 cm² beam area, with pulsed beam 9.500 Hz and 30 seconds of exposure time per point and emitted energy 1.2 J) before grip strength training. The LLLT was timed to contact 10 points located in the region of the superficial and deep flexor muscles of the fingers, with a total energy of 12.0 J per session. For the strength training protocol, the volunteer exercised their fingers with the dominant hand on a small table, elbow flexed at 90°, forearm in neutral, using a light extension handle. The Oxford protocol was performed during four weeks. The grip strength was assessed using a dynamometer (Jamar™). The data were evaluated by the analysis of variance (ANOVA) statistical method. Results: In the comparison of intragroup evaluation, only the 904 nm group showed a difference compared to the baseline assessment after 4 weeks (P < 0.05), in the final intergroup evaluation, a difference was observed in the comparison between the control and 904 nm groups Conclusion: In conclusion, LLLT (904 nm) applied before resistance training was effective in gaining grip strength when compared to LLLT (660 nm) and isolated strength training after 4 weeks.

Strength training prior to muscle injury potentiates low-level laser therapy (LLLT)-induced muscle regeneration

We evaluated whether strength training (ST) performed prior to skeletal muscle cryolesion would act as a preconditioning, improving skeletal muscle regeneration and responsiveness to low-level laser therapy (LLLT). Wistar rats were randomly assigned into non-exercised (NE), NE plus muscle lesion (NE + LE), NE + LE plus LLLT (NE + LE + LLLT), strength training (ST), ST + LE, and ST + LE + LLLT. The animals performed 10 weeks of ST (climbing ladder; 3× week; 80% overload). Forty-eight hours after the last ST session, tibialis anterior (TA) cryolesion was induced and LLLT (InGaAlP, 660 nm, 0.035 W, 4.9 J/cm²/point, 3 points, spot light 0.028 cm², 14 J/cm²) initiated and conducted daily for 14 consecutive days. The difference between intergroups was assessed using Student's t test and intragroups by two-way analysis of variance. Cryolesion induced massive muscle degeneration associated with inflammatory infiltrate. Prior ST improved skeletal regeneration 14-days after cryolesion and potentiated the regenerative response to LLLT. Cryolesion induced increased TNF-α levels in both NE + LE and ST + LE groups. Both isolated ST and LLLT reduced TNF-α to control group levels; however, prior ST potentiated LLLT response. Both isolated ST and LLLT increased IL-10 levels with no additional effect. In contrast, increased TA IL-6 levels were restricted to ST and ST + LE + LLLT groups. TA myogenin mRNA levels were not changed by neither prior ST or ST + LLLT. Both prior ST and LLLT therapies increased MyoD mRNA levels and, interestingly, combined therapies potentiated this response. Myf5 mRNA levels were increased only in ST groups. Taken together, our data provides evidences for prior ST potentiating LLLT efficacy in promoting skeletal muscle regeneration.

Photobiomodulation in human muscle tissue: an advantage in sports performance?

Photobiomodulation (PBM) describes the use of red or near-infrared (NIR) light to stimulate, heal, and regenerate damaged tissue. Both preconditioning (light delivered to muscles before exercise) and PBM applied after exercise can increase sports performance in athletes. This review covers the effects of PBM on human muscle tissue in clinical trials in volunteers related to sports performance and in athletes. The parameters used were categorized into those with positive effects or no effects on muscle performance and recovery. Randomized controlled trials and case-control studies in both healthy trained and untrained participants, and elite athletes were retrieved from MEDLINE up to 2016. Performance metrics included fatigue, number of repetitions, torque, hypertrophy; measures of muscle damage and recovery such as creatine kinase and delayed onset muscle soreness. Searches retrieved 533 studies, of which 46 were included in the review (n = 1045 participants). Studies used single laser probes, cluster of laser diodes, LED clusters, mixed clusters (lasers and LEDs), and flexible LED arrays. Both red, NIR, and red/NIR mixtures were used. PBM can increase muscle mass gained after training, and decrease inflammation and oxidative stress in muscle biopsies. We raise the question of whether PBM should be permitted in athletic competition by international regulatory authorities.

Use of low-level laser therapy (808 nm) to muscle fatigue resistance: a randomized double-blind crossover trial

OBJECTIVE

The purpose of this study was to investigate whether low-level laser (light) therapy (LLLT) can provide fatigue resistance via maximum repetitions (RM) with an isokinetic dynamometer, and decrease electromyography fatigue index (EFI).

BACKGROUND DATA

LLLT has been used to increase muscle performance when applied before or after intense exercises.

MATERIALS AND METHODS

This study was a randomized, double-blind, crossover trial with placebo. Seven young men (21±3 years of age) who were clinically healthy, were allocated into two groups: active laser (LLLT) and placebo laser (Placebo). Both groups were assessed at baseline, at one training session, and at the end of this study. Baseline and final assessments recorded the number of RM of knee flexion-extensions using an isokinetic dynamometer at 60 degrees/sec in conjunction with EFI recorded by median frequency. The training sessions consisted of three sets of 20 RM of knee flexion-extensions using an isokinetic dynamometer at 60 degrees/sec plus LLLT (808 nm, 100 mW, 4 J), or placebo, applied to quadriceps femoris muscles between sets, and after the last series of this exercise. After 1 week (washout period), all volunteers were exchanged among groups and then all assessments were repeated.

RESULTS

LLLT group increased RM (52%; p=0.002) with a small EFI for the vastus medialis (p=0.004) and rectus femoris (p=0.004).

CONCLUSIONS

These results suggest an increased muscle fatigue resistance when LLLT is applied during rest intervals, and after the last series of intense exercises.

Low-level laser therapy reduces the fatigue index in the ankle plantar flexors of healthy subjects

Low-level laser therapy (LLLT) has been suggested as a resource capable of increasing resistance to fatigue and enhancing muscle performance through its metabolic and photochemical effects. This study evaluated the immediate effects of the application of LLLT on neuromuscular performance of the plantar ankle flexors in healthy subjects through a fatigue-induced protocol. This is a randomized controlled clinical trial, attended by 60 young and physically active volunteers of both genders. The subjects were randomly assigned into three groups, control, placebo, and laser, and underwent a preliminary evaluation of the isokinetic performance of plantar flexors and electromyographic activity of the soleus muscle to ensure homogeneity between groups. After the application of the respective intervention protocols, participants were induced to fatigue by performing 100 isokinetic concentric contractions of ankle plantar flexors at a speed of 90°/s. The dynamometric fatigue index (DFI) and median frequency were recorded during the fatigue protocol for comparison between groups. The group receiving the laser application showed significantly lower dynamometric fatigue index (p = 0.036) when compared to control and placebo groups. In relation to the median frequency during the fatigue test, there was a decrease in all groups, however with no differences between them. We suggest that LLLT being applied prior to exercise can reduce the fatigue index in the ankle plantar flexors of healthy subjects.

What is the best moment to apply phototherapy when associated to a strength training program? A randomized, double-blinded, placebo-controlled trial : Phototherapy in association to strength training

The effects of phototherapy (or photobiomodulation therapy) with low-level laser therapy (LLLT) and/or light-emitting diodes (LEDs) on human performance improvement have been widely studied. Few studies have examined its effect on muscular training and no studies have explored the necessary moment of phototherapy irradiations (i.e., before and/or after training sessions). The aim of this study was to determine the optimal moment to apply phototherapy irradiation when used in association with strength training. Forty-eight male volunteers (age between 18 to 35 years old) completed all procedures in this study. Volunteers performed the strength training protocol where either a phototherapy and/or placebo before and/or after each training session was performed using cluster probes with four laser diodes of 905 nm, four LEDs of 875 nm, and four LEDs of 640 nm-manufactured by Multi Radiance Medical™. The training protocol duration was 12 weeks with assessments of peak torque reached in maximum voluntary contraction test (MVC), load in 1-repetition maximum test (1-RM) and thigh circumference (perimetry) at larger cross-sectional area (CSA) at baseline, 4 weeks, 8 weeks, and 12 weeks. Volunteers from group treated with phototherapy before and placebo after training sessions showed significant (p < 0.05) changes in MVC and 1-RM tests for both exercises (leg extension and leg press) when compared to other groups. With an apparent lack of side effects and safety due to no thermal damage to the tissue, we conclude that the application of phototherapy yields enhanced strength gains when it is applied before exercise. The application may have additional beneficial value in post-injury rehabilitation where strength improvements are needed.

Effect of pre-exercise phototherapy applied with different cluster probe sizes on elbow flexor muscle fatigue

Phototherapy has been used for reducing muscle fatigue. In view of the various types of phototherapy cluster probes available in the market, the purpose of this study was to compare the effects of a similar phototherapy dosage with two different cluster probes on elbow flexor muscle fatigue: small cluster probe (SC = 9 diodes; 7.5 cm(2)) vs. large cluster probe (LC = 33 diodes; 30.2 cm(2)). Ten physically active male aged 18-35 years participate in a randomized, crossover, double-blind, placebo-controlled trial, which each participant was submitted to the same testing protocol in four sessions (separated by at least 48 h) with different treatments: LC-phototherapy, SC-phototherapy, LC-placebo, and SC-placebo. The elbow flexion maximal isometric voluntary contraction (MIVC) was performed before and after a fatigue protocol (60 % of MIVC until exhaustion). Electromyography (EMG) of the biceps brachii muscle was collected during all testing procedure. Phototherapy with dose of 60 J per muscle [LC: 33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm); SC: 9 diodes = 5 lasers (850 nm) and 4 LEDs (670 nm)] or placebo applications occurred before fatigue protocol. Two-way ANOVA (treatment and time factors) and one-way ANOVA were used, followed by LSD post hoc. Time to exhaustion was significantly higher in active LC (15 %; p = 0.031) and SC (14 %; p = 0.038) in comparison with their respective placebo treatments, without differences between LC and SC (p > 0.05) or between placebo conditions (p > 0.05). This larger exercise tolerance in phototherapy conditions was not accompanied by a higher decrement in the volunteers' maximal strength capacity (11-15 %; p > 0.05 for all). EMG signals presented no difference between the four condition tested here. In both large and small cluster probes (according parameters tested in this study) led to reduced fatigue in elbow flexor muscles, without difference between them.

Acute effects of low-level laser therapy irradiation on blood lactate and muscle fatigue perception in hospitalized patients with heart failure-a pilot study

The objective of the present study is to evaluate the acute effects of low-level laser therapy (LLLT) on functional capacity, perceived exertion, and blood lactate in hospitalized patients with heart failure (HF). Patients diagnosed with systolic HF (left ventricular ejection fraction <45 %) were randomized and allocated prospectively into two groups: placebo LLLT group (n = 10)-subjects who were submitted to placebo laser and active LLLT group (n = 10)-subjects who were submitted to active laser. The 6-min walk test (6MWT) was performed, and blood lactate was determined at rest (before LLLT application and 6MWT), immediately after the exercise test (time 0) and recovery (3, 6, and 30 min). A multi-diode LLLT cluster probe (DMC, São Carlos, Brazil) was used. Both groups increased 6MWT distance after active or placebo LLLT application compared to baseline values (p = 0.03 and p = 0.01, respectively); however, no difference was observed during intergroup comparison. The active LLLT group showed a significant reduction in the perceived exertion Borg (PEB) scale compared to the placebo LLLT group (p = 0.006). In addition, the group that received active LLLT showed no statistically significant difference for the blood lactate level through the times analyzed. The placebo LLLT group demonstrated a significant increase in blood lactate between the rest and recovery phase (p < 0.05). Acute effects of LLLT irradiation on skeletal musculature were not able to improve the functional capacity of hospitalized patients with HF, although it may favorably modulate blood lactate metabolism and reduce perceived muscle fatigue.

Low level laser therapy associated with a strength training program on muscle performance in elderly women: a randomized double blind control study

The aging process leads to a gradual loss of muscle mass and muscle performance, leading to a higher functional dependence. Within this context, many studies have demonstrated the benefits of a combination of physical exercise and low level laser therapy (LLLT) as an intervention that enhances muscle performance in young people and athletes. The aim of this study was to evaluate the effects of combination of LLLT and strength training on muscle performance in elderly women. For this, a hundred elderly women were screened, and 48 met all inclusion criteria to participate in this double-blind placebo-controlled trial. Volunteers were divided in three groups: control (CG = 15), strength training associated with placebo LLLT (TG = 17), and strength training associated with active LLLT (808 nm, 100 mW, 7 J) (TLG = 16). The strength training consisted of knee flexion-extension performed with 80 % of 1-repetition maximum (1-RM) during 8 weeks. Several outcomes related to muscle performance were analyzed through the 6-min walk test (6-MWT), isokinetic dynamometry, surface electromyography (SEMG), lactate concentration, and 1-RM. The results revealed that a higher work (p = 0.0162), peak torque (p = 0.0309), and power (p = 0.0223) were observed in TLG compared to CG. Furthermore, both trained groups increased the 1-RM load (TG vs CG: p = 0.0067 and TLG vs CG: p < 0.0001) and decreased the lactate concentration in the third minute after isokinetic protocol (CG vs TLG: p = 0.0289 and CG vs TG: p = 0.0085). No difference in 6-MWT and in fatigue levels were observed among the groups. The present findings suggested that LLLT in combination with strength training was able to improve muscle performance in elderly people.

Effects of low-level laser therapy (LLLT 808 nm) on lower limb spastic muscle activity in chronic stroke patients

A cerebrovascular accident (CVA) may affect basic motor functions, including spasticity that may be present in the upper extremity and/or the lower extremity, post-stroke. Spasticity causes pain, muscle force reduction, and decreases the time to onset of muscle fatigue. Several therapeutic resources have been employed to treat CVA to promote functional recovery. The clinical use of low-level laser therapy (LLLT) for rehabilitation of muscular disorders has provided better muscle responses. Thus, the aim of this study was to evaluate the effect of the application of LLLT in spastic muscles in patients with spasticity post-CVA. A double-blind clinical trial was conducted with 15 volunteer stroke patients who presented with post-stroke spasticity. Both males and females were treated; the average age was 51.5 ± 11.8 years old; the participants entered the study ranging from 11 to 48 months post-stroke onset. The patients participated in three consecutive phases (control, placebo, and real LLLT), in which all tests of isometric endurance of their hemiparetic lower limb were performed. LLLT (diode laser, 100 mW 808 nm, beam spot area 0.0314 cm(2), 127.39 J/cm(2)/point, 40 s) was applied before isometric endurance. After the real LLLT intervention, we observed significant reduction in the visual analogue scale for pain intensity (p = 0.0038), increased time to onset of muscle fatigue (p = 0.0063), and increased torque peak (p = 0.0076), but no significant change in the root mean square (RMS) value (electric signal in the motor unit during contraction, as obtained with surface electromyography). Our results suggest that the application of LLLT may contribute to increased recruitment of muscle fibers and, hence, to increase the onset time of the spastic muscle fatigue, reducing pain intensity in stroke patients with spasticity, as has been observed in healthy subjects and athletes.

Effect of low-level phototherapy on delayed onset muscle soreness: a systematic review and meta-analysis

To determine the effectiveness of low-level phototherapy (i.e. light-emitting diode therapy [LEDtherapy] or light amplification by stimulated emission of radiation therapy [LASERtherapy]) on pain, skeletal muscle injury (creatine kinase [CK] levels and edema) and skeletal muscle function (range of movement and strength) in people undergoing an exercise protocol. (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PEDro, SciELO and LILACS up to May 2014), we included randomized controlled trials, quasi-randomized controlled trials and crossover studies in which study participants were allocated to receive either low-level phototherapy or placebo treatment. Phototherapy should have been applied in a single treatment session, either before or after an exercise protocol. We identified 15 studies involving 317 participants. Meta-analyses were limited by substantial heterogeneity. Compared to the placebo group, reduction in CK levels was only observed when LASERtherapy was applied before an exercise protocol (standardized mean difference = -0.66; 95 % CI = -1.30, -0.02). No between-group difference in edema, range of movement and strength were detected when phototherapy was applied before or after exercise. Evidence from this review suggests that low-level phototherapy may not have substantial effect in the treatment of skeletal muscle injury and pain caused by exercise. Definitive conclusions are limited due to the small number of included studies in each meta-analysis, disparities across the included studies and small sample sizes.

Influence of low-level laser therapy on vertical jump in sedentary individuals

Objective

To investigate the effects of low intensity laser (660nm), on the surae triceps muscle fatigue and power, during vertical jump in sedentary individuals, in addition to delayed onset muscle soreness.

Methods

We included 22 sedentary volunteers in the study, who were divided into three groups: G1 (n=8) without performing low intensity laser (control); G2 (n=7) subjected to 6 days of low intensity laser applications; and G3 (n=7) subjected to 10 days of low intensity laser applications. All subjects were evaluated by means of six evaluations of vertical jumps lasting 60 seconds each. In G2 and G3, laser applications in eight points, uniformly distributed directly to the skin in the region of the triceps surae were performed. Another variable analyzed was the delayed onset muscle soreness using the Visual Analog Scale of Pain.

Results

There was no significant difference in fatigue and mechanical power. In the evaluation of delayed onset muscle soreness, there was significant difference, being the first evaluation higher than the others.

Conclusion

The low intensity laser on the triceps surae, in sedentary individuals, had no significant effects on the variables evaluated.

Effect of low-level laser therapy (808 nm) on skeletal muscle after endurance exercise training in rats

BACKGROUND:

Low-level laser therapy (LLLT) has been demonstrated to be effective in optimizing skeletal muscle performance in animal experiments and in clinical trials. However, little is known about the effects of LLLT on muscle recovery after endurance training.

OBJECTIVE:

This study evaluates the effects of low-level laser therapy (LLLT) applied after an endurance training protocol on biochemical markers and morphology of skeletal muscle in rats.

METHOD:

Wistar rats were divided into control group (CG), trained group (TG), and trained and laser irradiated group (TLG). The endurance training was performed on a treadmill, 1 h/day, 5 days/wk, for 8 wk at 60% of the maximal speed reached during the maximal effort test (Tmax) and laser irradiation was applied after training.

RESULTS:

Both trained groups showed significant increase in speed compared to the CG. The TLG demonstrated a significantly reduced lactate level, increased tibialis anterior (TA) fiber cross-section area, and decreased TA fiber density. Myogenin expression was higher in soleus and TA muscles in both trained groups. In addition, LLLT produced myogenin downregulation in the TA muscle of trained animals.

CONCLUSION:

These results suggest that LLLT could be an effective therapeutic approach for stimulating recovery during an endurance exercise protocol.

Effects of low-level laser therapy on biceps braquialis muscle fatigue in young women

OBJECTIVE

This study aims to investigate the effects of low-level laser therapy (LLLT) on biceps brachi muscular fatigue in 20 young females.

BACKGROUND DATA

Exhausting physical activity leads to muscular fatigue, which could decrease muscular strength, and may cause impairment in motor control and muscle pain. Several biochemical and biophysical resources have been studied in an attempt to accelerate the recovery of muscle fatigue. Among these, LLLT is emphasized.

METHODS

Twenty subjects were randomized in one laser group and one placebo group in two sessions of a crossover design experimental procedure; the second session taking place within 7 days of the first. In the first session, subjects underwent a collection of surface electromyographic (SEMG) data of the biceps brachii muscle, followed by active or placebo LLLT at the same muscle, followed then by another EMG sample of biceps brachii. Blood samples were collected five times during the experimental procedure. Second session procedures were identical to the first, with exception of LLLT, which was the opposite of the first session. The fatigue protocol consisted of 60 sec of elbow flexion-extension movement performed with 75% of one maximum repetition. Blood lactate, EMG fatigue, and the number of elbow flexion-extension repetitions during the fatigue protocol were used to evaluate the effects of laser therapy (808 nm wavelength, 100 mW output power, power density of 35.7 W/cm(2), 70 sec each point and 7 J/point on eight points).

RESULTS

No statistical differences were found for eletromyographic fatigue and blood lactate values between groups. Mean numbers of elbow flexion-extension repetitions were 22.6 ± 7.58 after placebo, and 25.1 ± 9.89 after active LLLT group, but these differences were not statistically significant (p=0.342).

CONCLUSIONS

LLLT had limited effects on delaying muscle fatigue in a young female sample, although a tendency was observed in the active laser group toward showing lower electromyography fatigue of biceps brachii muscle. No intergroup differences were found in the number of muscle contractions and lactate concentration.

Thermal tomography imaging in photonic traditional Chinese medicine information therapy with holistic effect for health whole nursing

A photonic traditional Chinese medicine (TCM) information therapy was developed that has applications in whole health nursing including the prevention and treatment of ischemic cardiovascular and cerebrovascular diseases as well as the conditioning of the subhealth state. This therapy utilizes the beam of a 630 nm LED light to irradiate the oropharynx, while simultaneously employing two beams of 650 nm LED light to irradiate corresponding acupuncture points resulting in a synergistic outcome. This method was named “1 + 2 phototherapy.” The principle mechanism of the therapy is a series of photon induced biological effects that are triggered by stimulating the photosensitive tissues of the oropharynx. This tissue includes the oral mucosa, capillaries, lymph nodes, saliva glands, nerves, and Jingluo and is stimulated by light beams of certain photon energy and imitative acupuncture information. Thermal tomography imaging shows that the average temperature of the upper-body was improved significantly after oropharyngeal irradiation under irradiation of “Futu point”: the heat radiation of the spine, as well as chest, shoulders, arms, and clavicle, increased under irradiation of “Hoku,” whereas the overall average temperature was below the temperature before irradiation. The experiment indicates that this therapy can promote blood circulation, regulate varied physiological parameters, and have holistic effects in whole health nursing.