Evaluation of mitochondrial respiratory chain activity in muscle healing by low-level laser therapy

Tailoring photobiomodulation to enhance tissue regeneration

Photobiomodulation (PBM), the use of biocompatible tissue-penetrating light to interact with intracellular chromophores to modulate the fates of cells and tissues, has emerged as a promising non-invasive approach to enhancing tissue regeneration. Unlike photodynamic or photothermal therapies that require the use of photothermal agents or photosensitizers, PBM treatment does not need external agents. With its non-harmful nature, PBM has demonstrated efficacy in enhancing molecular secretions and cellular functions relevant to tissue regeneration. The utilization of low-level light from various sources in PBM targets cytochrome c oxidase, leading to increased synthesis of adenosine triphosphate, induction of growth factor secretion, activation of signaling pathways, and promotion of direct or indirect gene expression. When integrated with stem cell populations, bioactive molecules or nanoparticles, or biomaterial scaffolds, PBM proves effective in significantly improving tissue regeneration. This review consolidates findings from in vitro, in vivo, and human clinical outcomes of both PBM alone and PBM-combined therapies in tissue regeneration applications. It encompasses the background of PBM invention, optimization of PBM parameters (such as wavelength, irradiation, and exposure time), and understanding of the mechanisms for PBM to enhance tissue regeneration. The comprehensive exploration concludes with insights into future directions and perspectives for the tissue regeneration applications of PBM.

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.

LIGHTSITE III: 13-Month Efficacy and Safety Evaluation of Multiwavelength Photobiomodulation in Nonexudative (Dry) Age-Related Macular Degeneration Using the Lumithera Valeda Light Delivery System

PURPOSE

The LIGHTSITE III study evaluated multiwavelength photobiomodulation (PBM) therapy in nonexudative (dry) age-related macular degeneration (AMD) using the LumiThera Valeda Light Delivery System.

METHODS

LIGHTSITE III is a randomized, controlled trial to assess the safety and effectiveness of PBM in dry AMD. Subjects were given multiwavelength PBM (590, 660, and 850 nm) or Sham treatment delivered in a series of nine sessions over 3 to 5 weeks every four months over 24 months. Subjects were assessed for efficacy and safety outcomes. Data from the 13-month analysis are presented in this report.

RESULTS

A total of 100 subjects (148 eyes) with dry AMD were randomized. LIGHTSITE III met the primary efficacy best-corrected visual acuity endpoint with a significant difference between PBM (n = 91 eyes) and Sham (n = 54 eyes) groups (Between group difference: 2.4 letters (SE 1.15), CI: -4.7 to -0.1, P = 0.02) (PBM alone: 5.4 letters (SE 0.96), CI: 3.5 to 7.3, P < 0.0001; Sham alone: 3.0 letters (SE 1.13), CI: 0.7-5.2, P < 0.0001). The PBM group showed a significant decrease in new onset geographic atrophy ( P = 0.024, Fisher exact test, odds ratio 9.4). A favorable safety profile was observed.

CONCLUSION

LIGHTSITE III provides a prospective, randomized, controlled trial showing improved clinical and anatomical outcomes in intermediate dry AMD following PBM therapy.

Improvement of weanling pigs immune status and metabolic condition using ultraweak light

Weaning stress is the most common issue in swine farms, which increases mortality and morbidity. The use of artificial light is an option for modifying the immune system and metabolic pathways. This study aimed to evaluate the influence of ultraweak light (Photonia) on growth performance, immune system and metabolism of weanling pigs, and the carry-over effect on the growth performance in postweanling growing stages. A total of 30 weaned pigs with an average initial body weight of 7.06 ± 0.11 kg (age: 21 days) were allotted two treatments (Control and Photonia) with 15 replicates. The pelleted form diets were prepared for pigs in three phases including phase 1 (Days 0-14), phase 2 (Days 15-28) and phase 3 (Days 29-48). The gain-to-feed ratio (G:F) of pigs was significantly greater in the Photonia treatment. On Day 28, a higher concentration of immunoglobin A (IgA) (p < 0.01) and IgG (p < 0.01) was observed in the Photonia pigs. On Day 48, the Photonia treatment showed a greater serum IgA (p < 0.01) and IgG (p < 0.05). The concentration of interleukin (IL)-6 was decreased (p < 0.05) in the Photonia treatment. At Day 48, the concentrations of tumour necrotic factor-α, IL-1β and IL-6 in serum were decreased (p < 0.05) in pigs in the Photonia treatment. Metabolic pathways analysis showed that the Photonia treatment increased the d-glutamine, d-glutamate, alanine, aspartate, glutamate and phenylalanine compared with the control treatment. In conclusion, the use of Photonia for weanling pigs is recommended due to improved G:F, immune status and activation of amino acids metabolic pathways including d-glutamine, d-glutamate, alanine, aspartate, glutamate and phenylalanine.

Comparison of three different dosages of low-level laser therapy on expression of cell proliferation and inflammatory markers following ovariohysterectomy in rats

The objective of the current study was to evaluate Low-level laser therapy (LLLT) on the healing of incisional wounds following ovariohysterectomy in rats, by means of subjective histopathological and immunohistochemical analysis. A total of 72 female Wistar rats were categorised into four treatment groups (Group I; sacrification 4 hours following only one LLLT application, Group II; sacrification 7 days following only one LLLT application, Group III; sacrification 4 hours after two LLLT applications, and Group IV; sacrification 7 days after two LLLT applications). Each group was further divided into four different doses subgroups (Group Control [C, off mode LLLT application], L1 [1 J/cm2], L3 [3 J/cm2], and L6 [6 J/cm2]), with equal representation in each subgroup. Ovariohysterectomy was employed using two 2-cm-length midline abdominal incisions in the left and right sides of line alba. The Group C was assigned to the left side incision to each rat in the study. After irradiation, the tissue was subjected to histopathological analysis to determine the extent of mononuclear cell infiltration, edoema, and epithelialization. Additionally, immunohistochemical analysis was performed to evaluate the expression of proliferating cell nuclear antigen (pCNA) and inducible nitric oxide synthase (iNOS). Group L1 and L3 significantly decreased mononuclear cell infiltration compared with Group C in all treatment groups (p < 0.05). Group L3 significantly decreased edoema compared with Group C in all groups except for treatment Group I (p < 0.05). Group L2 and L3 significantly increased epithelization in treatment Group IV (p < 0.05). Moreover, Group L2 and L3 significantly increased pCNA in all groups, while L2 and L3 significantly decreased iNOS expression in treatment Group II, III, and IV (p < 0.05). However, no statistical difference was found between subgroups of treatment Group I in iNOS expiration (p > 0.05). The results of the current examination demonstrated that LLLT can modulate mononuclear cell infiltration and edoema, and improve epithelization, as well as increase pCNA expression, whereas decrease iNOS expression during the wound healing process, therefore enhancing wound healing following ovariohysterectomy in rats.

Effects of Photobiomodulation Therapy on Performance in Successive Time-to-Exhaustion Cycling Tests: A Randomized Double-Blinded Placebo-Controlled Trial

The goal of this study was to investigate the effects of photobiomodulation therapy (PBMT) on performance, oxygen uptake (VO2) kinetics, and lower limb muscle oxygenation during three successive time-to-exhaustions (TTEs) in cyclists. This was a double-blind, randomized, crossover, placebo-controlled trial study. Sixteen cyclists (~23 years) with a cycling training volume of ~460 km/week volunteered for this study. In the first session, cyclists performed a maximal incremental test to determine maximal oxygen uptake and maximal power output (POMAX). In the following sessions, cyclists performed three consecutive TTEs at POMAX. Before each test, PBMT (135 J/thigh) or a placebo (PLA) was applied to both thighs. VO2 amplitude, O2 deficit, time delay, oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), and total hemoglobin (tHb) were measured during tests on the right vastus lateralis. The PBMT applied before three successive TTE increased performance of the first and second TTE (~10-12%) tests, speed of VO2 and HHb kinetics during the first test, and increased peripheral muscle oxygenation (increase in HHb and tHb) in the first and second exhaustion tests. However, the PBMT effects were attenuated in the third TTE, as performance and all the other outcomes were similar to the ones from the PLA intervention. In summary, PBMT application increased the first and second successive TTEs, speed of VO2, and muscle oxygenation.

Effects of photobiomodulation and caffeine treatment on acute kidney injury in a hypoxic ischemic neonatal rat model

Hypoxic ischemic encephalopathy (HIE) occurs in 2-5/1000 births, with acute kidney injury (AKI) occurring in 40%. AKI increases morbidity and mortality. Caffeine, an adenosine receptor antagonist, and photobiomodulation (PBM), working on cytochrome c oxidase, are potential treatments for AKI. To examine effects of caffeine and PBM on AKI in rats, Day 7 pups underwent a HIE intervention (Modified Rice-Vannucci model) replicating pathology observed in humans. Caffeine was administered for 3 days and/or PBM for 5 days following HIE. Weights and urine for biomarkers (NGAL, albumin, KIM-1, osteopontin) were collected prior to HIE, daily post intervention and at sacrifice. Both treatments reduced kidney injury seen on electron microscopy, but not when combined. HIE elevated urinary NGAL and albumin on Days 1-3 post-HIE, before returning to control levels. This elevation was significantly reduced by PBM or caffeine. KIM-1 was significantly elevated for 7 days post-HIE and was reduced by both treatments. Osteopontin was not altered by HIE or the treatments. Treatments, individually but not in combination, improved HIE-induced reductions in the enzymatic activity of mitochondrial complexes II-III. PBM and caffeine also improved weight gain. PBM and caffeine reduces AKI diagnosed by urinary biomarkers and confirmed by EM findings.

Low-Level Photobiomodulation Therapy Modulates H2O2 Production, TRPC-6, and PGC-1α Levels in the Dystrophic Muscle

Objective: This study evaluated photobiomodulation therapy (PBMT) effects on the factors involved in mitochondrial biogenesis, on the mitochondrial respiratory complexes, and on the transient receptor potential canonical channels (such as TRPC-1 and TRPC-6) in in vitro (mdx muscle cells) and in vivo studies (gastrocnemius muscle) from mdx mice, the dystrophin-deficient model of Duchenne muscular dystrophy (DMD). Background: There is no successful treatment for DMD, therefore demanding search for new therapies that can improve the muscle role, the quality of life, and the survival of dystrophic patients. Methods: The dystrophic primary muscle cells received PBMT at 0.6 J and 5 J, and the dystrophic gastrocnemius muscle received PBMT at 0.6 J. Results: The dystrophic muscle cells treated with PBMT (0.6 J and 5 J) showed no cytotoxicity and significantly lower levels in hydrogen peroxide (H2O2) production. We also demonstrated, for the first time, the capacity of PBMT, at a low dose (0.6 J), in reducing the TRPC-6 content and in raising the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) content in the dystrophic gastrocnemius muscle. Conclusions: PBMT modulates H2O2 production, TRPC-6, and PGC-1α content in the dystrophic muscle. These results suggest that laser therapy could act as an auxiliary therapy in the treatment of dystrophic patients.

The effects of low-level laser therapy on muscle strength and functional outcomes in individuals with knee osteoarthritis: a double-blinded randomized controlled trial

The purpose of this study was to compare the therapeutic effects of low-level laser therapy (LLLT) with 808 and 660 nm wavelength on muscle strength and functional outcomes in individuals with knee osteoarthritis (OA). A total of 47 participants were randomly assigned to the 808 nm, 660 nm, and sham control groups. Two LLLT groups received continuous LLLT with a mean power of 300 mW in different wavelengths at the knee joint 15 min a session three days per week for eight weeks, while the control group received the sham LED treatment. The knee strength and functional performance involving 30-s sit-to-stand, 40 m fast-paced walk, stair climbing, and the TUG test were measured at the baseline and one week after the interventions were completed. The results showed that knee extensor strength was more improved in the 808 nm group as compared to the 660 nm group (p < 0.001, d = 0.57) and the sham control (p < 0.001, d = 0.40), while increased flexor strength was demonstrated in the 808 nm (p = 0.009, d = 0.67) and sham control groups (p < 0.001, d = 0.97). The number of 30-s sit-to-stand was increased only in the 660 nm group (p = 0.006, d = 0.49). All three groups exhibited improvements in the other three functional performance-based tests after the interventions with no statistically significant differences among the groups. In conclusion, both intervention groups improved muscle strength and functional performance as compared to the control group. The 808 nm wavelength group showed better results in knee extensor strength. Therefore, laser therapy is suggested to be integrated into rehabilitation programs to improve muscle strength and functional performance in the population with knee OA.

Efficacy of low-level laser therapy in patients with lower extremity tendinopathy or plantar fasciitis: systematic review and meta-analysis of randomised controlled trials

OBJECTIVES

We investigated the effectiveness of low-level laser therapy (LLLT) in lower extremity tendinopathy and plantar fasciitis on patient-reported pain and disability.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Eligible articles in any language were identified through PubMed, Embase and Physiotherapy Evidence Database (PEDro) on the 20 August 2020, references, citations and experts.

ELIGIBILITY CRITERIA FOR SELECTION OF STUDIES

Only randomised controlled trials involving participants with lower extremity tendinopathy or plantar fasciitis treated with LLLT were included.

DATA EXTRACTION AND SYNTHESIS

Random effects meta-analyses with dose subgroups based on the World Association for Laser Therapy treatment recommendations were conducted. Risk of bias was assessed with the PEDro scale.

RESULTS

LLLT was compared with placebo (10 trials), other interventions (5 trials) and as an add-on intervention (3 trials). The study quality was moderate to high.Overall, pain was significantly reduced by LLLT at completed therapy (13.15 mm Visual Analogue Scale (VAS; 95% CI 7.82 to 18.48)) and 4-12 weeks later (12.56 mm VAS (95% CI 5.69 to 19.42)). Overall, disability was significantly reduced by LLLT at completed therapy (Standardised Mean Difference (SMD)=0.39 (95% CI 0.09 to 0.7) and 4-9 weeks later (SMD=0.32 (95% CI 0.05 to 0.59)). Compared with placebo control, the recommended doses significantly reduced pain at completed therapy (14.98 mm VAS (95% CI 3.74 to 26.22)) and 4-8 weeks later (14.00 mm VAS (95% CI 2.81 to 25.19)). The recommended doses significantly reduced pain as an add-on to exercise therapy versus exercise therapy alone at completed therapy (18.15 mm VAS (95% CI 10.55 to 25.76)) and 4-9 weeks later (15.90 mm VAS (95% CI 2.3 to 29.51)). No adverse events were reported.

CONCLUSION

LLLT significantly reduces pain and disability in lower extremity tendinopathy and plantar fasciitis in the short and medium term. Long-term data were not available. Some uncertainty about the effect size remains due to wide CIs and lack of large trials.

PROSPERO REGISTRATION NUMBER

CRD42017077511.

Effect of Photobiomodulation on Denervation-Induced Skeletal Muscle Atrophy and Autophagy: A Study in Mice

OBJECTIVE

The purpose of this study was to investigate whether photobiomodulation (PBM) can protect against and attenuate muscle atrophy owing to complete peripheral nerve lesion in mice by acting on autophagy.

METHODS

C57BL/10 mice underwent right sciatic nerve transection to induce tibialis anterior muscle atrophy. After 6 hours of denervation, the mice received PBM (wavelength, 830 nm) daily, transcutaneously over the tibialis anterior muscle region for 5 or 14 days. Some mice with sciatic nerve lesion did not receive PBM. Mice that did not have sciatic nerve lesion and PBM were used as controls. After 5 and 14 days, the right tibialis anterior muscle was examined using histomorphometric (cross-sectional area of muscle fibers), Western blot (levels of the autophagy marker LC3), and immunofluorescence analyses (number of LC3 puncta in the muscle fibers).

RESULTS

The cross-sectional area of the tibialis anterior muscle fibers decreased after 5 and 14 days of denervation. PBM protected against muscle fiber atrophy after 5 days of denervation and attenuated muscle fiber atrophy after 14 days of denervation. After 5 days of muscle denervation, autophagy did not change, as demonstrated by the comparable levels of LC3-I/II ratio and LC3 puncta between the controls and the mice with atrophic muscle; PBM did not change this profile. After 14 days of denervation, an increased LC3-I/II ratio suggested an ongoing autophagy, which was not affected by PBM.

CONCLUSION

PBM attenuated the tibialis anterior muscle atrophy induced by sciatic nerve transection in the mice after at least 5 and 14 days of muscle denervation, without affecting autophagy. The transient protective effect of PBM was observed as early as 5 days after the of complete nerve lesion.

Photobiomodulation associated with lipid nanoparticles and hyaluronic acid accelerate the healing of excisional wounds

Objectives: This article aimed to investigate the effects of the association between photobiomodulation and hyaluronic acid incorporated in lipid nanoparticles in an epithelial lesion model in inflammatory parameters and oxidative stress. Methods: Eighty Wistar rats were randomly assigned to the following groups: epithelial lesion group (EL); EL+PBM; EL+HA; EL+SLNs; EL+SLNs-HA; EL+PBM+HA; EL+PBM+SLNs; EL+PBM+SLNs-HA. The animals were anesthetized with 4% isofluorane after shaving and induced to an epithelial lesion. Topical treatment with a gel containing HA (0.9%) and/or SLNs (10 mg/mL) and with laser irradiation occurred daily for 1 week. Results: The results showed an increase in wound contraction on the seventh day in the LE + LBM + AH-NPL group, a reduction in pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α), an increase in anti-inflammatory cytokines (IL- 4 and IL-10) and TGF-β. The levels of pro-inflammatory cytokine IL-4 and TGF-β also showed an increase in the LE + NPL-AH, LE + FBM + AH, LE + FBM + NPL and LE + FBM + NPL-AH groups. Regarding oxidative stress parameters, the levels of DCF and nitrite decreased in the combined therapy group when compared to the control group, as well as oxidative damage (carbonyl and sulfhydryl). In the antioxidant defense, there was an increase in GSH and SOD in the combination therapy group. Histological analysis showed a reduction in inflammatory infiltrate in the combination therapy group. The number of fibroblasts and the compaction of collagen fibers did not obtain significant responses. Conclusions: Results analyzed together showed that the combined therapy favored the repair process, and that studies can be carried out to enhance the histological analysis therapy favored the tissue repair process and that studies can be carried out to enhance the histological analysis.

Effects of moderate aerobic exercise, low-level laser therapy, or their combination on muscles pathology, oxidative stress and irisin levels in the mdx mouse model of Duchenne muscular dystrophy

This study aimed to investigate how the combined use of low-level laser therapy (LLLT) and exercise, to reduce the possible side effects and/or increase the benefits of exercise, would affect oxidative stress, utrophin, irisin peptide, and skeletal, diaphragmatic, and cardiac muscle pathologies. In our study, 20 mdx mice were divided into four groups. Groups; sedentary and placebo LLLT (SC), sedentary and LLLT (SL), 30-min swimming exercise (Ex), and 30-min swimming exercise and LLLT (ExL). After 8 weeks of swimming exercise, muscle tests, biochemically; oxidative stress index (OSI), utrophin and irisin levels were measured. Skeletal, diaphragmatic and cardiac muscle histopathological scores, skeletal and cardiac muscle myocyte diameters were determined under the light and electron microscope. While only irisin levels were increased in group SL compared to SC, it was determined that OSI, heart muscle histopathological scores decreased and irisin levels increased in both exercise groups (p < 0.05). In addition, in the ExL group, an increase in rotarod and utrophin levels, and a decrease in muscle and diaphragm muscle histopathological scores were observed (p < 0.05). It was determined that the application of swimming exercise in the mdx mouse model increased the irisin level in the skeletal muscle, while reducing the OSI, degeneration in the heart muscle, inflammation and cardiopathy. When LLLT was applied in addition to exercise, muscle strength, skeletal muscle utrophin levels increased, and skeletal and diaphragmatic muscle degeneration and inflammation decreased. In addition, it was determined that only LLLT application increased the level of skeletal muscle irisin.

NIR Laser Photobiomodulation Induces Neuroprotection in an In Vitro Model of Cerebral Hypoxia/Ischemia

Brain photobiomodulation (PBM) is an innovative treatment for a variety of neurological conditions, including cerebral ischemia. However, the capability of PBM for ischemic stroke needs to be further explored and its mechanisms of action remain currently unclear. The aim of the present research was to identify a treatment protocol capable of inducing neuroprotection and to investigate the molecular mechanisms activated by a dual-wavelength near infrared (NIR) laser source in an organotypic hippocampal slice model of hypoxia/ischemia. Hippocampal slices were exposed to oxygen and glucose deprivation (OGD) for 30 min followed by NIR laser light (fluence 3.71, 7.42, or 14.84 J/cm²; wavelengths 808 nm and 905 nm) delivered immediately or 30 min or 60 min after OGD, in order to establish a therapeutic window. Neuronal injury was assessed by propidium iodide fluorescence 24 h later. Our results show that NIR laser irradiation attenuates OGD neurotoxicity once applied immediately or 30 min after OGD. Western blot analysis of proteins involved in neuroinflammation (iNOS, COX-2, NFkB subunit p65, and Bcl-2) and in glutamatergic-mediated synaptic activity (vGluT1, EAAT2, GluN1, and PSD95) showed that the protein modifications induced by OGD were reverted by NIR laser application. Moreover, CA1 confocal microscopy revealed that the profound morphological changes induced by OGD were reverted by NIR laser radiation. In conclusion, NIR laser radiation attenuates OGD neurotoxicity in organotypic hippocampal slices through attenuation of inflammatory mechanisms. These findings shed light on molecular definition of NIR neuroprotective mechanisms, thus underlining the potential benefit of this technique for the treatment of cerebral ischemia.

On-Site Laser Photobiomodulation Treatment of Crushed Muscle Due to Prolonged Pressure in Rats

BACKGROUND AND OBJECTIVES

Crush injuries and prolonged pressure on muscles lead to bruises and sprains and, in most of the cases, cause distraction of the muscle and release of particles into the blood stream, causing renal and systemic complications in severe cases. Laser photobiomodulation treatment (i.e., laser phototherapy) is a method suggested to decrease the pressure damage in the first 24-48 hours after muscle injury, allowing a faster and more complete physical rehabilitation. We studied the efficacy of non-invasive laser photobiomodulation treatment as an on-site treatment for crush-injured gastrocnemius muscles, developing a moderate muscle crush injury model and aiming at decreasing damage extent while regaining physical competence faster.

STUDY DESIGN/MATERIALS AND METHODS

Muscle crush injury was performed on 30 female Wistar rats using direct pressure for 10 minutes on the gastrocnemius muscle in both left and right hindlimbs. Immediately after the injury, only the left hindlimb were irradiated for 16 minutes (with 780 nm laser with a power of 250 mW, the energy at the target was 240 J, and the fluence was 1019 J/cm² ) for 1, 3, or 7 consecutive days, and sacrificed accordingly. During the follow-up period, 1, 3, or 7 days, both gastrocnemius muscles (of the treated and untreated hindlimbs) were evaluated for electrophysiology and functionality.

RESULTS

The laser photobiomodulation treatment showed a significant electrophysiological and functional recovery of the gastrocnemius muscle during the first 3 days after injury, in comparison with the untreated hindlimb.

CONCLUSIONS

These preliminary results are promising, showing a significant effect of the laser photobiomodulation treatment during the first 3 days after the induction of the muscle crush injury, which is the most critical period in the clinical aspect. These findings suggest a therapeutic approach, which may help restore the muscle after crush injury.

Oxidative stress is involved in LLLT mechanism of action on skin healing in rats

The skin injury healing process involves the main phases of homoeostasis, inflammation, proliferation, and remodeling. The present study aimed to analyze the effects of low-level laser therapy (LLLT) on hematological dynamics, oxidative stress markers, and its relation with tissue healing following skin injury. Wistar rats were divided into control, sham, skin injury, and skin injury LLLT. The biochemical and morphological analyses were performed in the inflammatory (1 and 3 days) and regenerative phases (7, 14, and 21 days) following injury. The skin injury was performed in the dorsal region, between the intrascapular lines, using a surgical punch. LLLT (Al-Ga-In-P, λ=660 nm, energy density of 20 J/cm², 30 mW power, and a time of 40 s) was applied at the area immediately after injury and on every following day according to the experimental subgroups. LLLT maintained hematocrit and hemoglobin levels until the 3rd day of treatment. Surprisingly, LLLT increased total leukocytes levels compared to control until the 3rd day. The effects of LLLT on mitochondrial activity were demonstrated by the significant increase in MTT levels in both inflammatory and regenerative phases (from the 1st to the 7th day), but only when associated with skin injury. The results indicated that LLLT modulated the inflammatory response intensity and accelerated skin tissue healing by a mechanism that involved oxidative damage reduction mostly at early stages of skin healing (inflammatory phase).

Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications

The development of a painless, non-invasive, and faster way to diabetic wound healing is at the forefront of research. The complexity associated with diabetic wounds makes it a cause for concern amongst diabetic patients and the world at large. Irradiation of cells generates a photobiomodulatory response on cells and tissues, directly causing alteration of cellular processes and inducing diabetic wound repair. Photobiomodulation therapy (PBMT) using red and near-infrared (NIR) wavelengths is being considered as a promising technique for speeding up the rate of diabetic wound healing, eradication of pain and reduction of inflammation through the alteration of diverse cellular and molecular processes. This review presents the extent to which the potential of red and NIR wavelengths have been harnessed in PBMT for diabetic wound healing. Important research challenges and gaps are identified and discussed, and future directions mapped out. This review thus provides useful insights and strategies into improvement of PBMT, including its acceptance within the global medical research community.

The Signalling Effects of Photobiomodulation on Osteoblast Proliferation, Maturation and Differentiation: A Review

Proliferation of osteoblasts is essential for maturation and mineralization of bone matrix. Ossification, the natural phase of bone-forming and hardening is a carefully regulated phase where deregulation of this process may result in insufficient or excessive bone mineralization or ectopic calcification. Osteoblasts can also be differentiated into osteocytes, populating short interconnecting passages within the bone matrix. Over the past few decades, we have seen a significant improvement in awareness and techniques using photobiomodulation (PBM) to stimulate cell function. One of the applications of PBM is the promotion of osteoblast proliferation and maturation. PBM research results on osteoblasts showed increased mitochondrial ATP production, increased osteoblast activity and proliferation, increased and pro-osteoblast expression in the presence of red and NIR radiation. Osteocyte differentiation was also accomplished using blue and green light, showing that different light parameters have various signalling effects. The current review addresses osteoblast function and control, a new understanding of PBM on osteoblasts and its therapeutic impact using various parameters to optimize osteoblast function that may be clinically important. Graphical Abstract.

Effect of adjunctive diode laser in the non-surgical periodontal treatment in patients with diabetes mellitus: a systematic review and meta-analysis

This study aimed to systematically review and analyze the present randomized clinical trials (RCTs) regarding the clinical efficacy of a diode laser (DL) adjuvant to scaling and root planning (SRP) in patients with chronic periodontitis (CP) who have diabetes mellitus (DM). Five databases (MEDLINE, EMBASE, Cochrane Central Register of Controlled Trails, Web of Science, and Chinese BioMedical Literature Databases) were searched. A meta-analysis was implemented to evaluate periodontal parameters including probing depth (PD) and clinical attachment level (CAL) as primary outcomes. Hemoglobin A1c (HbA1c), plaque index (PI), and the gingival index (GI) were also observed as secondary outcomes. Independent scanning of 239 papers resulted in 9 RCTs. Moderate evidence demonstrated that the test groups showed significant benefits for PD reduction, CAL gain, and HbA1c reduction after 3 and 6 months. Significant differences in PI and GI reduction were not found except for GI reduction within 1 month. The collective evidence suggested that the DL with SRP had significant improvements in clinical results compared to SRP alone. Based on our results, the DL could be a recommended therapy for patients with CP who have DM.

Comparison Of The Efficacy Of Two Laser Types In Healing Of Full-Thickness Wound: An Experimental Study

The aim of the study ― To investigate the effectiveness of pulsed laser with high intensity and laser with low intensity on a full-thickness wound in rats and to compare the effects of both laser types. Material and Methods ― Forty-five adult male rats were utilized in the present study. After anesthesia, wound of five cm2 was produced on dorsal aspect in each rat; then, the rats were randomly classified into three groups as follows: high power pulsating laser group (A) which received Nd: YAG laser with 1064 nm wavelength, low power laser group (B) which received GaAlAs laser with 830 nm wavelength, and control group (C) which received no treatment. Laser lights in groups (A) and (B) were introduced at an intensity of five joules per cm2 with a total energy of 25 joules for each wound area through the use of a scanning method and at a rate of 3 sessions per week for three weeks. Results ― At the end of treatment, better wound healing in form of more wound contraction and higher healing rate was elicited in both laser groups in comparison to wound healing in the control group, and there were no significantly different effects between both laser types. Conclusion ― At the intensity of five joules/cm2, both low-intensity and pulsating high-intensity lasers speed up the healing of the wound in rats, and there are no significant differences between their effects.

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).

Effect of Photobiomodulation Therapy in the 1500 m Run: An Analysis of Performance and Individual Responsiveness

Objective: The aims of this study were to verify the effects of photobiomodulation therapy (PBMT) on time trial run performance over 1500 m, as well as on individual responsiveness of recreative runners. Materials and methods: Nineteen recreationally trained runners participated in a randomized, crossover, double-blind placebo-controlled trial. The study was divided in four sessions: (1) incremental maximal running test; (2) 1500 m run control (without placebo or PBMT); and (3, 4) PBMT or placebo before 1500 m run. PBMT or placebo was applied over 14 sites per lower limb immediately before time trial run using a mixed wavelength device (33 diodes: 5 LASERs of 850 nm, 12 LEDs of 670 nm, 8 LEDs of 880 nm, and 8 LEDs with 950 nm). PBMT delivered 30 J per site, with a total energy dose of 840 J. Physiological variables [maximal oxygen uptake (VO_2MAX), velocity associated to VO_2MAX (vVO_2MAX), peak of velocity, and respiratory compensation point (RCP)] were assessed during incremental maximal test. During 1500 m races we accessed the following: time, heart rate, and lower limb rate perception exertion per lap, total time, and blood lactate concentration ([Lac]). Results: PBMT had no significant difference and likely trivial effect for performance in the total time trial run over 1500 m compared to placebo. In the responsiveness analyses, 10 participants positively responded to PBMT, whereas total time reduced for responders (-10.6 sec; -3.18%) and increased for nonresponders (+6.0 sec; +1.73%). Responders presented higher aerobic parameters (VO_2MAX and RCP) than nonresponders. Moreover, responders had lower time per lap and [Lac] (1 and 3 min) when PBMT was applied. Conclusions: PBMT applied immediately before running in noncontrolled environment was not able to improve the 1500 m performance of recreationally trained runners. However, responders to PBMT presented higher aerobic capacity than nonresponders.

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).

Does Previous Application of Photobiomodulation Using Light-Emitting Diodes at Different Energy Doses Modify the Peak Running Velocity and Physiological Parameters? A Randomized, Crossover, Double-Blind, and Placebo-Controlled Study

Objective: This study aimed to verify the acute effects of photobiomodulation (PBM) using different doses of LED on peak running velocity (V_peak) and physiological parameters. Materials and methods: The study had a randomized, crossover, double-blind, and placebo-controlled format, in which 15 physically active males were submitted, besides the control (CON), to four conditions performed 5 min before the maximal incremental treadmill tests for the determination of V_peak: placebo (PLA) and three conditions of PBM application at different doses: PBM applied with 30 J per area (PBM₁), PBM applied with 120 J per area (PBM₂), and PBM applied with 180 J per area (PBM₃). The LED was applied using an equipment with 56 diodes of red light (660 nm; 50 mW/cm² and 1.5 J/cm² each diode) and 48 diodes of infrared light (850 nm; 150 mW/cm² and 4.5 J/cm² each diode). The PBM was applied in two regions of the quadriceps muscle, two regions of the femoral biceps muscle, and one region of the gastrocnemius muscle in both legs. Results: There was no difference among the outcomes from PBM irradiations and PLA condition for the variables, V_peak (CON = 13.4 ± 1.6; PLA = 13.4 ± 1.6; PBM₁ = 13.5 ± 1.7; PBM₂ = 13.4 ± 1.6; PBM₃ = 13.4 ± 1.7 km/h), similar to other variables associated with aerobic running performance analyzed during the maximal incremental treadmill tests for V_peak determination: lactate peak, heart rate, and rating of perceived exertion. Conclusions: We concluded that the application of different doses of PBM using LEDs did not modify V_peak and physiological and perceptual parameters.

Photobiomodulation Therapy Effects on Resistance Training Volume and Discomfort in Well-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Trial

Objective: To investigate the effects of photobiomodulation therapy (PBMT) on resistance training volume and discomfort of well-trained adults. Background: PBMT has been used to attenuate fatigue in several physical exercise topics. However, it is unclear if PBMT can increase volume and reduce discomfort in resistance training well-trained individuals. Methods: Fourteen participants (women = 7, 27.7 ± 6.0 years and men = 7, 28.3 ± 5.7 years) visited the laboratory three times, 7 days apart. In the first visit, 12-repetition maximum (12-RM) test was performed unilaterally on the standing calf raise machine. In the second and third visits, subjects were randomly submitted to a PBMT (60 J per site, 6 sites per limb, total dose = 360 J) or placebo treatment on the gastrocnemius and soleus muscles with a randomized crossover design. Five minutes after the treatment, subjects began the resistance training session, performed unilaterally with six sets of repetitions to concentric failure. In addition, the rate of perceived exertion for discomfort (RPE-D) was asked after each set. Results: After the training session, it was observed a similar force reduction of 10.0 ± 13.6% for placebo and 7.7 ± 7.3% for PBMT (p = 0.815). No differences between PBMT and placebo was observed for the repetitions fatigue index (53.4 ± 11.7% and 50.0 ± 11.6%; p = 0.325) and total repetitions volume (55.4 ± 10.9 and 54.8 ± 13.0 reps; p = 0.764), respectively. RPE-D presented large means for all sets representing a large discomfort during resistance training to concentric failure for both PBMT (7.3 ± 2.3) and placebo (7.5 ± 2.5). Conclusions: The PBMT was not effective for increasing volume and reducing discomfort during resistance training performed to concentric failure by well-trained men and women.

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.

In vitro effects of 635 nm photobiomodulation under hypoxia/reoxygenation culture conditions

Photobiomodulation (PBM), especially in the red wavelength range, has been demonstrated to be an effective treatment option for superficial and chronic wounds. However, ischemia and subsequent reperfusion can further challenge wound healing. Therefore, we investigated the effect of pulsed red LED light at 635 nm on cellular function in an in-vitro model of hypoxia/reoxygenation (H/R) challenge. Mouse myoblasts and fibroblasts were incubated in oxygen-deprived starvation medium (hypoxia) for 3 h after which the media was changed to oxygenated, fully supplemented media to simulate reperfusion. Cells were then treated with pulsed red LED light at a wavelength of 635 nm at 40 mW/cm². Mitochondrial respiratory activity, ATP production and ROS levels were analysed immediately post-illumination. The effects on cellular metabolic activity and proliferation were measured at 6 h and 24 h and apoptosis/necrosis was measured at 24 h post-illumination. Our results show that both cell types reacted differently to H/R challenge and PBM. PBM of H/R-challenged cells enhanced mitochondrial activity and rescued decreased ATP levels, with significant effects in fibroblasts. This was associated with increased cell proliferation rates in both cell types. The increase was again more pronounced in fibroblasts. Our study concluded that PBM with red LED light significantly restored ATP levels during H/R and effectively promoted cell growth under both normoxic and H/R conditions. In clinical applications, PBM has been repeatedly reported to resolve difficult clinical situations in which ischemia/reperfusion injuries are a major issue. Our study confirms the beneficial effects of PBM especially in H/R-challenged cells.

Role of 904 nm superpulsed laser-mediated photobiomodulation on nitroxidative stress and redox homeostasis in burn wound healing

BACKGROUND

Burn wound healing is delayed due to several critical factors such as sustained inflammation, vascular disorder, neuropathy, enhanced proteolysis, infection, and oxidative stress. Burn wounds have limited oxygen supply owing to compromised blood circulation. Hypoxic burn milieu leads to free radicals overproduction incurring oxidative injury, which impedes repair process causing damage to cell membranes, proteins, lipids, and DNA. Photobiomodulation (PBM) with 904 nm superpulsed laser had shown potent healing efficacy via attenuating inflammation while enhancing proliferation, angiogenesis, collagen accumulation, and bioenergetic activation in burn wounds.

METHODS

This study investigated the effects of 904 nm superpulsed laser at 0.4 mW/cm² average power density, 0.2 J/cm² total energy density, 100 Hz frequency, and 200 ns pulse width for 10 min daily for seven days postburn injury on nitroxidative stress, endogenous antioxidants status, and redox homeostasis.

RESULTS

Photobiomodulation treatment significantly decreased reactive oxygen species, nitric oxide, and lipid peroxidation levels as compared to non-irradiated control. Further, protective action of PBM against protein oxidative damage was evidenced by reduced protein carbonylation and advanced oxidation protein product levels along with significantly enhanced endogenous antioxidants levels of SOD, catalase, GPx, GST, reduced glutathione, and thiol (T-SH, Np-SH, P-SH). Biochemical changes aid in reduction of oxidative stress and maintenance of redox homeostasis, which further well corroborated by significantly up-regulated protein expression of Nrf 2, hemeoxygenase (HO-1), and thioredoxin reductase 2 (Txnrd2).

CONCLUSION

Photobiomodulation with 904 nm superpulsed laser led to reduction of nitroxidative stress, induction of endogenous antioxidants, and maintenance of redox homeostasis that could play a vital role in augmentation of burn wound healing.

Healing Effects of Photobiomodulation on Diabetic Wounds

Diabetic patients frequently develop chronic ulcers of the lower extremities, which are a frequent cause for hospitalization and amputation, placing strain on patients, their families, and healthcare systems. Present therapies remain a challenge, with high recurrence rates. Photobiomodulation (PBM), which is the non-invasive application of light at specific wavelengths, has been shown to speed up healing of chronic wounds, including diabetic foot ulcers (DFUs). PBM produces photophysical and photochemical changes within cells without eliciting thermal damage. It has been shown to promote tissue regeneration and speed up wound repair by reducing inflammation and oxidative stress, accelerating cell migration and proliferation, and promoting extracellular matrix production and release of essential growth factors. The shortage of rigorous, well-designed clinical trials makes it challenging to assess the scientific impact of PBM on DFUs, and lack of understanding of the underlying mechanisms also hinders the conventional use of this therapy. This review gives a glimpse into diabetic wound healing and PBM, and the effects of PBM on diabetic wound healing.

Transcranial Photobiomodulation For The Management Of Depression: Current Perspectives

Major depressive disorder (MDD) is a prevalent condition associated with high rates of disability, as well as suicidal ideation and behavior. Current treatments for MDD have significant limitations in efficacy and side effect burden. FDA-approved devices for MDD are burdensome (due to repeated in-office procedures) and are most suitable for severely ill subjects. There is a critical need for device-based treatments in MDD that are efficacious, well-tolerated, and easy to use. In this paper, we review a novel neuromodulation strategy, transcranial photobiomodulation (t-PBM) with near-infrared light (NIR). The scope of our review includes the known biological mechanisms of t-PBM, as well as its efficacy in animal models of depression and in patients with MDD. Theoretically, t-PBM penetrates into the cerebral cortex, stimulating the mitochondrial respiratory chain, and also significantly increases cerebral blood flow. Animal and human studies, using a variety of t-PBM settings and experimental models, suggest that t-PBM may have significant efficacy and good tolerability in MDD. In aggregate, these data support the need for large confirmatory studies for t-PBM as a novel, likely safe, and easy-to-administer antidepressant treatment.

Can mild cognitive impairment be stabilized by showering brain mitochondria with laser photons?

There is now substantial evidence that cerebral blood flow (CBF) declines with age. From age 20 to 60, CBF is estimated to dip about 16% and continues to drop at a rate of 0.4%/year. This CBF dip will slowly reduce oxygen/glucose delivery to brain thus lowering ATP energy production needed by brain cells to perform normal activities. Reduced ATP production from mitochondrial loss or damage in the wear-and-tear of aging worsens when vascular risk factors (VRF) to Alzheimer's disease develop that can accelerate both age-decline CBF and mitochondrial deficiency to a level where mild cognitive impairment (MCI) develops. To date, no pharmacological or any other treatment has been successful in reversing, stabilizing or delaying MCI. For the first time in medical interventions, a non-pharmacological, non-invasive, well-tolerated, easy to perform, free of significant side effects and cost-effective treatment may achieve what virtually all AD treatments in the past have been unable to accomplish. This intervention uses transcranial infrared brain stimulation (TIBS), a form of photobiomodulation (PBM). PBM is a bioenergetic non-ionizing, therapeutic approach using low level light emission from laser or light emitting diodes. PBM has been used in a number of neurological conditions including Parkinson's disease, depression, traumatic brain injury, and stroke with diverse reported benefits. This brief review examines the impact of reduced energy supply stemming from chronic brain hypoperfusion in the aging brain. In this context, the use of TIBS is planned in a randomized, placebo-controlled study of MCI patients to be done at our University Clinic. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Light-emitting diode irradiation using 660 nm promotes human fibroblast HSP90 expression and changes cellular activity and morphology

We evaluated changes in cell viability and morphology in response to low-level light irradiation and underlying variations in the levels of heat shock proteins (HSPs). Human fibroblasts were irradiated with a light-emitting diode (LED) array at 660 nm (50 mW for 15, 30, and 60 minutes). Cell viability and morphological changes were evaluated via epifluorescence analysis; we also assessed cell viability and length changes. The expression levels of adenosine triphosphate (ATP) and various HSPs (HSP27, 60, 70, and 90) were analyzed by immunohistochemical staining, Western blotting and microarray analysis. After LED irradiation, cellular viability and morphology changed. Of the several HSPs analyzed, the HSP90 level increased significantly, suggesting that this protein played roles in the morphological and cellular changes. Thus, low-level irradiation triggered cellular changes mediated by increased HSP90 expression; this may explain why skin irradiation enhances wound-healing.

Photobiomodulation Therapy Does Not Attenuate Fatigue and Muscle Damage in Judo Athletes: A Randomized, Triple-Blind, Placebo-Controlled Trial

Fatigue and muscle damage negatively affect performance in lower limb exercises involving the stretch-shortening cycle in judo athletes during competition and training sessions. Photobiomodulation therapy has emerged as an effective non-invasive strategy to attenuate fatigue and muscle damage when applied before different types of exercises. Our objective was to investigate the effects of photobiomodulation therapy on fatigue and muscle damage in judo athletes. Sixteen judo athletes participated in the study (23.1 ± 3.8 years, 77.9 ± 14.9 kg, 173.1 ± 8.9 cm, 17.5 ± 7.3 body fat%, 12.9 ± 5.0 years of practice). Each participant received, in a randomized manner, photobiomodulation in one limb and placebo in the contralateral limb on the same day. Thereafter, subjects performed a stretch-shortening cycle protocol to induce muscle fatigue and damage. Countermovement jump (impulse, peak power, peak velocity, and peak force), echo intensity (rectus femoris and vastus lateralis), and muscle soreness were assessed at different time points before, during, immediately post, and 24 and 48 h after the protocol. Muscle fatigue was detected due to reductions in countermovement jump impulse (14.7 ± 9.8 and 15.9 ± 15.5%), peak power (12.9 ± 8.5 and 11.9 ± 6.9%), peak velocity (8.6 ± 8.1 and 6.5 ± 6.0%), and peak force (7.0 ± 5.3 and 8.0 ± 6.1%) after the protocol (p < 0.001), for placebo and photobiomodulation therapy, respectively. Muscle damage was detected due to reductions in countermovement jump impulse (−6.1 ± 19.2% and −4.5 ± 9.2%, p < 0.05), increases in echo intensity (rectus femoris, 21.0 ± 11.9 and 20.8 ± 9.0%; and vastus lateralis, 22.4 ± 23.2%; and 16.7 ± 23.8%; p < 0.001), and quadriceps muscle soreness (3.6 ± 1.6 and 3.5 ± 1.7 a.u; p < 0.011), 48 h after the protocol, for placebo and photobiomodulation therapy, respectively. No differences were observed between photobiomodulation therapy and placebo at any time points for any variables (p > 0.05), indicating no positive effect favoring photobiomodulation therapy. In conclusion, our findings suggest no effect of photobiomodulation therapy applied before exercise to reduce lower limb muscle fatigue and damage during and following a stretch-shortening cycle protocol in judo athletes.

Effects of photobiomodulation on mitochondria of brain, muscle, and C6 astroglioma cells

The purpose of this study was to investigate the effect of different doses of photobiomodulation (PBM) on mitochondrial respiratory complexes and oxidative cellular energy metabolic enzymes in the mitochondria of brain, muscle, and C6 glioma cells after different time intervals. C6 cells were irradiated with an AlGaInP laser at 10, 30, and 60 J/cm² for 20, 60, and 120 s, respectively. After irradiation, the cells were maintained in serum-free Dulbecco's Modified Eagle's medium for 24 h, and biochemical measurements were made subsequently. Mitochondrial suspensions from adult rat skeletal muscles/brains were irradiated with an AlGaInP laser at the abovementioned doses. In one group, the reaction was stopped 5 min after irradiation and in the other 60 min after irradiation. Both the C6 cells that received the doses of 10 and 30 J/cm² showed increased complex I activity; the cells that were irradiated at 30 J/cm² showed increased hexokinase activity. Five minutes after the introduction of PBM of the muscle mitochondria (at 30 and 60 J/cm²), the activity of complex I increased, while the activity of complex IV increased only at 60 J/cm². One hour after the laser session, complex II activity increased in the cells treated with 10 and 60 J/cm²; however, complex IV activity showed an increase in all PBM groups. In brain mitochondria, 5 min after irradiation only the activity of complex IV increased in all PBM groups. One hour after the laser session, complex II activity increased at 60 J/cm², and complex IV activity increased for all PBM groups when compared to controls. PBM could increase the activity of respiratory chain complexes in an apparently dose- and time-dependent manner.

Effect of NIR laser therapy by MLS-MiS source against neuropathic pain in rats: in vivo and ex vivo analysis

Neuropathic pain is characterized by an uncertain etiology and by a poor response to common therapies. The ineffectiveness and the frequent side effects of the drugs used to counteract neuropathic pain call for the discovery of new therapeutic strategies. Laser therapy proved to be effective for reducing pain sensitivity thus improving the quality of life. However, its application parameters and efficacy in chronic pain must be further analyzed. We investigated the pain relieving and protective effect of Photobiomodulation Therapy in a rat model of compressive mononeuropathy induced by Chronic Constriction Injury of the sciatic nerve (CCI). Laser (MLS-MiS) applications started 7 days after surgery and were performed ten times over a three week period showing a reduction in mechanical hypersensitivity and spontaneous pain that started from the first laser treatment until the end of the experiment. The ex vivo analysis highlighted the protective role of laser through the myelin sheath recovery in the sciatic nerve, inhibition of iNOS expression and enhancement of EAAT-2 levels in the spinal cord. In conclusion, this study supports laser treatment as a future therapeutic strategy in patients suffering from neuropathic pain induced by trauma.

The Effectiveness of Photobiomodulation Therapy Versus Cryotherapy for Skeletal Muscle Recovery: A Critically Appraised Topic

Clinical Scenario: Cryotherapy is one of the most commonly used modalities for postexercise muscle recovery despite inconsistencies in the literature validating its effectiveness. With the need to find a more effective modality, photobiomodulation therapy (PBMT) has gained popularity because of recent research demonstrating its ability to accelerate the muscle recovery process. Focused Clinical Question: Is PBMT more effective than cryotherapy at reducing recovery time and decreasing delayed onset muscle soreness after strenuous exercise? Summary of Key Findings: Three moderate- to high-quality double-blinded, randomized, placebo-controlled trials and 2 low- to moderate-quality translational studies performed on rats were included in this critically appraised topic. All 5 studies supported the use of PBMT over cryotherapy as a treatment for postexercise muscle recovery following exercise. PBMT was superior in reducing creatine kinase, inflammation markers, and blood lactate compared with cryotherapy, following strenuous/high intensity aerobic or strength muscular exercise. PBMT was also shown to improve postexercise muscle performance and function more than cryotherapy. Clinical Bottom Line: There is moderate evidence to suggest the use of PBMT over cryotherapy postexercise to enhance muscle recovery in trained and untrained athletes. Shorter recovery times and increased muscle performance can be seen 24 to 96 hours following PBMT application. Strength of Recommendation: Based on consistent findings from all 5 studies, there is grade B evidence to support the use of PBMT over cryotherapy for more effective postexercise recovery of skeletal muscle performance.

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.

In Vivo Analysis of Photobiomodulation Genotoxicity Using the Somatic Mutation and Recombination Test

BACKGROUND

Photobiomodulation (PBM) has been studied mainly for its effects on the repair, regeneration, and healing of tissue due to its direct and indirect actions on cell proliferation. However, it is necessary to consider the way in which laser acts, that is, whether it affects the rates of spontaneous mutation and mitotic recombination of cells.

OBJECTIVE

This study investigated the genotoxic potential of PBM (904 nm) based on an in vivo bioassay that concomitantly evaluates mitotic recombination and point and chromosomal mutations.

METHODS

Strains of Drosophila melanogaster that carry specific marker genes were used to detect the induction of mutation and somatic recombination when exposed to different fluences (3, 5, 10, and 20 J/cm²). DNA damage was measured using the somatic mutation and recombination test (SMART), which is based on the identification of wing hair with mutant phenotypes that express lesions at DNA level.

RESULTS

The doses 5, 10, and 20 J/cm² induced significant increase in the total number of spots compared with the negative control. The highest frequency of spots was caused by the 10 J/cm².

CONCLUSIONS

Besides recombination events, the quantitative and qualitative analysis of mutant hairs revealed the occurrence of mutagenic events, both punctual and chromosomal. In addition, the results point to a dose-dependent response.

Acute effects of photobiomodulation therapy (PBMT) combining laser diodes, light-emitting diodes, and magnetic field in exercise capacity assessed by 6MST in patients with COPD: a crossover, randomized, and triple-blinded clinical trial

Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea, as well as musculoskeletal and systemic manifestations. Photobiomodulation therapy (PBMT) with use of low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) is an electrophysical intervention that has been found to minimize or delay muscle fatigue. The aim of this study was to evaluate the acute effect of PBMT with combined use of lasers diodes, light-emitting diodes (LEDs), magnetic field on muscle performance, exercise tolerance, and metabolic variables during the 6-minute stepper test (6MST) in patients with COPD. Twenty-one patients with COPD (FEV₁ 46.3% predicted) completed the 6MST protocol over 2 weeks, with one session per week. PBMT/magnetic field or placebo (PL) was performed before each 6MST (17 sites on each lower limb, with a dose of 30 J per site, using a cluster of 12 diodes 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs; Multi Radiance Medical™, Solon, OH, USA). Patients were randomized into two groups before the test according to the treatment they would receive. Assessments were performed before the start of each protocol. The primary outcomes were oxygen uptake and number of steps, and the secondary outcome was perceived exertion (dyspnea and fatigue in the lower limbs). PBMT/magnetic field applied before 6MST significantly increased the number of steps during the cardiopulmonary exercise test when compared to the results with placebo (129.8 ± 10.6 vs 116.1 ± 11.5, p = 0.000). PBMT/magnetic field treatment also led to a lower score for the perception of breathlessness (3.0 [1.0-7.0] vs 4.0 [2.0-8.0], p = 0.000) and lower limb fatigue (2.0 [0.0-5.0] vs 4.0 [0.0-7.0], p = 0.001) compared to that with placebo treatment. This study showed that the combined application of PBMT and magnetic field increased the number of steps during the 6MST and decreased the sensation of dyspnea and lower limb fatigue in patients with COPD.

LED session prior incremental step test enhance VO2max in running

This study aimed to investigate the effect of prior LED sessions on the responses of cardiorespiratory parameters during the running incremental step test. Twenty-six healthy, physically active, young men, aged between 20 and 30 years, took part in this study. Participants performed two incremental load tests after placebo (PLA) and light-emitting diode application (LED), and had their gas exchange, heart rate (HR), blood lactate, and rating of perceived exertion (RPE) monitored during all tests. The PLA and LED conditions were compared using the dependent Student t test with significance set at 5%. The T test showed higher maximum oxygen uptake (VO_2max) (PLA = 47.2 ± 5.7; LED = 48.0 ± 5.4 ml kg^-1 min^-1, trivial effect size), peak velocity (V_peak) (PLA = 13.4 ± 1.2; LED = 13.6 ± 1.2 km h^-1, trivial effect size), and lower maximum HR (PLA = 195.3 ± 3.4; LED = 193.3 ± 3.9 b min^-1, moderate effect size) for LED compared to PLA conditions. Furthermore, submaximal values of HR and RPE were lower, and submaximal VO₂ values were higher when LED sessions prior to the incremental step test were applied. A positive response of the previous LED application in the blood lactate disappearance was also demonstrated, especially 13 and 15 min after the test. It is concluded that LED sessions prior to exercise modify cardiorespiratory response by affecting running tolerance during the incremental step test, metabolite clearance, and RPE. Therefore, LED could be used as a prior exercise strategy to modulate oxidative response acutely in targeted muscle and enhance exercise tolerance.

The effects of exercise training associated with low-level laser therapy on biomarkers of adipose tissue transdifferentiation in obese women

Investigations suggest the benefits of low-level laser therapy (LLLT) to improve noninvasive body contouring treatments, inflammation, insulin resistance and to reduce body fat. However, the mechanism for such potential effects in association with exercise training (ET) and possible implications in browning adiposity processes remains unclear. Forty-nine obese women were involved, aged between 20 and 40 years with a body mass index (BMI) of 30-40 kg/m². The volunteers were divided into Phototherapy (808 nm) and SHAM groups. Interventions consisted of exercise training and phototherapy applications post exercise for 4 months, with three sessions/week. Body composition, lipid profile, insulin resistance, atrial natriuretic peptide (ANP), WNT5 signaling, interleukin-6 (IL-6), and fibroblast growth factor-21 (FGF-21) were measured. Improvements in body mass, BMI, body fat mass, lean mass, visceral fat, waist circumference, insulin, HOMA-IR, total cholesterol, LDL-cholesterol, triglycerides, and ANP in both groups were demonstrated. Only the Phototherapy group showed a reduction in interleukin-6 and an increase in WNT5 signaling. In addition, it was possible to observe a higher magnitude change for the fat mass, insulin, HOMA-IR, and FGF-21 variables in the Phototherapy group. In the present investigation, it was demonstrated that exercise training associated with LLLT promotes an improvement in body composition and inflammatory processes as previously demonstrated. The Phototherapy group especially presented positive modifications of WNT5 signaling, FGF-21, and ANP, possible biomarkers associated with browning adiposity processes. This suggests that this kind of intervention promotes results applicable in clinical practice to control obesity and related comorbidities.

Inhibitory modulation of cytochrome c oxidase activity with specific near-infrared light wavelengths attenuates brain ischemia/reperfusion injury

The interaction of light with biological tissue has been successfully utilized for multiple therapeutic purposes. Previous studies have suggested that near infrared light (NIR) enhances the activity of mitochondria by increasing cytochrome c oxidase (COX) activity, which we confirmed for 810 nm NIR. In contrast, scanning the NIR spectrum between 700 nm and 1000 nm revealed two NIR wavelengths (750 nm and 950 nm) that reduced the activity of isolated COX. COX-inhibitory wavelengths reduced mitochondrial respiration, reduced the mitochondrial membrane potential (ΔΨ_m), attenuated mitochondrial superoxide production, and attenuated neuronal death following oxygen glucose deprivation, whereas NIR that activates COX provided no benefit. We evaluated COX-inhibitory NIR as a potential therapy for cerebral reperfusion injury using a rat model of global brain ischemia. Untreated animals demonstrated an 86% loss of neurons in the CA1 hippocampus post-reperfusion whereas inhibitory NIR groups were robustly protected, with neuronal loss ranging from 11% to 35%. Moreover, neurologic function, assessed by radial arm maze performance, was preserved at control levels in rats treated with a combination of both COX-inhibitory NIR wavelengths. Taken together, our data suggest that COX-inhibitory NIR may be a viable non-pharmacologic and noninvasive therapy for the treatment of cerebral reperfusion injury.

Muscle fiber conduction velocity and EMG amplitude of the upper trapezius muscle in healthy subjects after low-level laser irradiation: a randomized, double-blind, placebo-controlled, crossover study

Although low-level laser therapy (LLLT) is an important resource for the treatment of non-specific neck pain patients, the dose which presents the greatest therapeutic potential for the treatment of this pathology is still unclear. The present study aimed to evaluate the immediate effect of LLLT on the muscle fiber conduction velocity (MFCV) and electromyographic activity (EMG) of the upper trapezius (UT) muscle in healthy individuals. A total of 20 healthy subjects were enrolled in a randomized, double-blind, crossover study. Active LLLT (820 nm wavelength, 30 mW, energy total 18 J) or placebo LLLT (pLLLT) was delivered on the UT muscle. Each subject was subjected to a single session of active LLLT and pLLLT. Surface electromyography (sEMG) signal of the UT muscle was recorded during five different step contractions of shoulder elevation force (10-30% maximal voluntary contraction) pre- and post-LLLT irradiation. The values of MFCV and sEMG global amplitude (RMS_G) were used to calculate the effects of LLLT. The results showed no difference in the MFCV comparing the LLLT and pLLLT groups (F = 0.72 p = 0.39, η _p² = 0.004). However, a significant difference was observed in the RMS_G between the LLLT and pLLLT (F _1,2 = 16.66; P < 0.0001, η _p² = 0.09). Individuals who received active LLLT presented a significant decrease in RMS_G after laser application (F = 61.28; p < 0.0001, η _p² = 0.43). In conclusion, the 820 nm LLLT, with energy total of 18 J, did not alter the MFCV but significantly reduced the sEMG signal amplitude of the upper trapezius muscle in healthy subjects to a level of up to 30% of maximal voluntary contraction.