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.     

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 _p ²?=?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 _p ²?=?0.09). Individuals who received active LLLT presented a significant decrease in RMS_G after laser application (F?=?61.28; p?<?0.0001, η _p ²?=?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.     

Low-level laser therapy in the management of plantar fasciitis: a randomized controlled trial

This study aimed at estimating the extent to which a combination therapy of low-level laser therapy (LLLT) with exercise and orthotic support (usual care) affects functional ability in the patient with plantar fasciitis (PF) when compared to usual care alone. Participants with PF were randomly allocated into two groups: LLLT (n?=?27) and control (n?=?22). All the participants received home exercise program with orthotic support. In addition, the LLLT group received a gallium-aluminum-arsenide laser with a 850-nm wavelength for ten sessions, three times a week. Functional outcomes were measured by function subscale of American Orthopedic Foot and Ankle Society Score (AOFAS-F) and 12-min walking test including walking speed, cadence, and activity-related pain using visual analog scale (VAS).The scores were recorded at baseline, third week, and third month after the treatment. Analysis was performed using repeated measures ANOVA and an intention to treat approach using multiple imputations. There was a significant improvement in AOFAS-F total score at 3 weeks in both groups (LLLT, p?<?0.001; control, p?=?0.002), but the improvements were seen only for the LLLT group for AOFAS-F total score (p?=?0.04) and two individual items of AOFAS-F (walking distance (p?<?0.001) and walking surface (p?=?0.01)) at 3 months. The groups were comparable with each other for both walking speed and cadence at all assessment times (p?>?0.05). Both groups showed significant reduction in pain over 3 months (LLLT, p?<?0.001; control, p?=?0.01); however, the LLLT group had lower pain than the control group at 3 months (p?=?0.03). The combination therapy of LLLT with usual care is more effective to improve functional outcomes and activity-related pain when compared to usual care alone.     

Effect of low-level laser therapy on tooth sensitivity induced by in-office bleaching

This study aimed to investigate the effect of low-level laser therapy (LLLT) on tooth sensitivity induced by in-office bleaching. Sixty-six patients enrolled in this randomized clinical trial. Following the in-office procedure with 40 % hydrogen peroxide, the participants were randomly divided into three groups. The patients in group 1 received irradiation from a low-level red laser (LLRL; 660 nm, 200 mW, 15 s, 12 J/cm²), whereas participants in group 2 were subjected to a low-level infrared laser (LLIL; 810 nm) under similar conditions as in group 1. In group 3 (placebo), the laser treatment was the same as that in groups 1 and 2, but without energy output. The degree of tooth sensitivity was recorded at 1, 24, and 48 h after bleaching using a visual analog scale (VAS). The change in tooth shade was measured 30 days after tooth whitening. The intensity of tooth sensitivity was not significantly different between groups at 1 h after bleaching (p?>?0.05). At 24 h after therapy, pain level was significantly lower in the LLIL group compared to the LLRL and placebo groups (p?<?0.05). At 48 h after bleaching, VAS scores in the LLIL and LLRL groups were comparable to each other (p?>?0.05) and both were significantly lower than that of the placebo group (p?<?0.05). There was no significant difference in the efficacy of tooth whitening among groups (p?>?0.05). LLLT with an infrared diode laser could be recommended as a suitable strategy to reduce the intensity of tooth sensitivity after in-office bleaching.     

Effect of photobiomodulation on connective tissue remodeling and regeneration of skeletal muscle in elderly rats

The purpose of this study was to evaluate the effects of low-level laser therapy (LLLT) on morphological aspects, IL-6 and IL-1β expressions, as well as the distribution and organization of collagen in the tibialis anterior (TA) muscle of elderly rats submitted to cryoinjury. Histological photomicrographs were taken of TA muscles stained with HE and picrosirius red. Immunohistochemistry was used for the evaluation of IL-6 and IL-1β. Male Wistar rats, aged 20 months, were distributed into three groups: (1) control animals not injured or treated with LLLT (n?=?5), (2) cryoinjury without LLLT treatment (n?=?15), and (3) cryoinjury treated with infrared LLLT (n?=?15). LLLT was applied to the TA 2 h after of the injury induction and consisted of daily applications until the sacrifice (1, 3, and 7 days). The following parameters were used: λ?=?780 nm, power density 1 W/cm², output power 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. In the histomorphological analysis, the treated group exhibited a significant decrease in inflammatory infiltrate (p?<?0.001) as well as an increase immature fibers and new blood vessels at 7 days compared to the untreated group (p?<?0.05). Furthermore, treatment induced a better collagen distribution and organization at 7 days in comparison to the untreated group (p?<?0.05). In conclusion, LLLT demonstrated a modulatory effect on the muscle repair process in elderly animals with regard to the collagen remodeling and morphological aspects of muscle tissue.     

Low-level laser therapy stimulates tissue repair and reduces the extracellular matrix degradation in rats with induced arthritis in the temporomandibular joint

The objective of this study was to characterize morphological and biochemistry action of low-level laser therapy (LLLT) on induced arthritis in the temporomandibular joint (TMJ) of rats. Twenty-four male Wistar rats were randomly divided into groups with 12 animals each: (AG) group with arthritis induced in the left TMJ and (LG) group with arthritis induced in the left TMJ and treated with LLLT (830 nm, 30 mW, 3 J/cm²). Right TMJs in the AG group were used as noninjected control group (CG). Arthritis was induced by intra-articular injection of 50 μl Complete Freund’s Adjuvant (CFA) and LLLT began 1 week after arthritis induction. Histopathological analysis was performed using sections stained with hematoxylin-eosin, Toluidine Blue, and picrosirius. Biochemical analysis was determined by the total concentration of sulfated glycosaminoglycans (GAGs) and evaluation of matrix metalloproteinases (MMP-2 and MMP-9). Statistical analysis was performed using paired and unpaired t tests, with p?<?0.05. Compared to AG, LG had minor histopathological changes in the TMJ, smaller thickness of the articular disc in the anterior (p?<?0.0001), middle (p?<?0.0001) and posterior regions (p?<?0.0001), high birefringence of collagen fibers in the anterior (p?<?0.0001), middle (p?<?0.0001) and posterior regions (p?<?0.0001) on the articular disc, and statistically lower activity of MMP-2 latent (p?<?0.0001), MMP-2 active (P?=?0.02), MMP-9 latent (p?<?0.0001), and MMP-9 active (p?<?0.0001). These results suggest that LLLT can increase the remodeling and enhancing tissue repair in TMJ with induced arthritis.     

Low-level laser therapy combined to functional exercise on treatment of fibromyalgia: a double-blind randomized clinical trial

This study aims to investigate the effects of low-level laser therapy (LLLT) combined to a functional exercise program on treatment of FM. A double-blind and placebo-controlled randomized clinical trial composed of 22 women divided into two groups: placebo group (functional exercise program associated with placebo phototherapy n?=?11) and laser group (same exercise program associated with active phototherapy; n?=?11). Each session lasted from 40 to 60 min and was performed three times a week for 8 weeks. Phototherapy (808 nm, 100 mW, 4 J, and 142.85 J/cm² per point) was bilaterally applied to different points of the quadriceps (8), hamstrings (6), and triceps sural muscles (3) immediately after each exercise session. Pre- and post-intervention evaluations regarding pain (sites, intensity, and threshold), functional performance (balance, functional tests), muscle performance (flexibility and isokinetic variables), depression, and quality of life were conducted. A reduction in pain and improvement in functional and muscular performance, depression, and quality of life were observed in both groups (p?<?0.05); however, with no significant differences between them (p?>?0.05). In conclusion, the benefic effects of functional exercise were not improved by combination with LLLT.     

Low-intensity laser (660 nm) on sternotomy healing in patients who underwent coronary artery bypass graft: a randomized,double-blind study

The aim of this study was to analyze the healing effects of low-level laser therapy (LLLT) on the longitudinal sternotomy incisions of patients who underwent coronary artery bypass graft (CABG). The volunteers were randomized into three groups of equal size (n?=?30): control, placebo, and laser (λ?=?660 nm and spatial average energy fluency [SAEF]?=?1.06 J/cm²). The patients in the laser group underwent irradiation on postoperative days 2, 4, 6, and 8, and their sternotomy incisions were photographed immediately after the surgery and 8 days later for analysis. Three researchers who were blinded to the patient treatment groups analyzed the incision photographs to assess hyperemia and wound closure on the day of hospital discharge (eighth postoperative day). The sternotomy incisions in the LLLT group demonstrated less hyperemia, incisional bleeding, and dehiscence (p?≤?0.005).     

Effect of low-level laser therapy after rapid maxillary expansion: a clinical investigation

To evaluate the effectiveness low-level laser therapy (LLLT) on the repair of the mid palatal suture, after rapid maxillary expansion (RME). A single-operator, randomized single-blind placebo-controlled study was performed at the Orthodontic Department at the Dental Hospital of Bellvitge. Barcelona University, Hospitalet de Llobregat, Spain. Thirty-nine children (range 6–12 years old), completed RME and were randomized to receive active LLLT (n?=?20) or placebo (n?=?19). The laser parameters and dose were 660 nm, 100 mW, CW, InGaAlP laser, illuminated area 0.26 cm², 332 mW/cm², 60 s to four points along midpalatal suture, and 30 s to a point each side of the suture. A total of seven applications were made on days 1, 7, 14, 28, 42, 56, and 70 of the retention phase RME. A cone beam computed tomography (CBCT) scan was carried out on the day of the first laser treatment, and at day 75, a second CBCT scan was performed. Two radiologists synchronized the slices of two scans to be assessed. P?=?0.05 was considered to be statistically significant. At day 75 of the suture, the irradiated patients presented a greater percentage of approximate zones in the anterior (p?=?0.008) and posterior (p?=?0.001) superior suture—and less approximation in the posterior superior suture (p?=?0.040)—than the placebo group. LLLT appears to stimulate the repair process during retention phase after RME.     

Anti-inflammatory and lymphangiogenetic effects of low-level laser therapy on lymphedema in an experimental mouse tail model

The aim of the present study was to investigate the therapeutic mechanism of low-level laser therapy (LLLT) in the mouse tail lymphedema model. Six-week-old female mice were classified into the laser treatment group, sham treatment group, and surgical control group (10 mice per group). LLLT was administered daily for 10 min from the surgical day to 11 days (12 times). Macrophage activation and lymphatic vessel regeneration were evaluated through immunohistochemical staining with anti-F4/80 and anti-LYVE-1 antibodies, respectively, at 12 days post-procedure. Quantitative real-time polymerase chain reaction (qPCR) was performed to measure messenger RNA (mRNA) expression of vascular endothelial growth factor A, B, C, R1, R2, and R3 (VEGF-A, VEGF-B, VEGF-C, VEGFR1, VEGFR2, and VEGFR3) at 12 days post-procedure. Student’s t and one-way ANOVA tests were performed for statistical analyses. Significance was defined as p?<?0.05. The thickness of the tail rapidly increased until 6 days in the laser and sham groups. The mice in the laser group showed a significantly decreased thickness compared with the sham group at 10 and 12 days. Immunohistochemistry assay revealed that LLLT reduced inflammation and induced new lymphatic vessel growth. qPCR showed that expressions of VEGFR3 were (p?=?0.002) increased in the laser group. These results suggest that LLLT has anti-inflammatory and lymphangiogenetic effects for the management of lymphedema.     

The effects of photobiomodulation and low-amplitude high-frequency vibration on bone healing process: a comparative study

This study aimed at investigating the effects of photobiomodulation (PBM) and low-amplitude high-frequency (LAHF) whole body mechanical vibration on bone fracture healing process when metallic plates are implanted in rats’ femurs. Forty male rats weighing between 250 and 350 g, 12 weeks old, were employed in this study. A transverse critical size defect (CSD) was made in their right femurs that were fixed by stainless steel plates. After the surgery, the rats were divided equally into four groups: low-level laser therapy group (GaAlAs laser, 830 nm, 40 mW, 4 J/cm², 0.35 cm beam diameter, LLLT), whole body vibration group (60 Hz, 0.1 mm amplitude, 1.5 g, WBV), a combination of laser and vibration group (LV), and the control group (C). Each group was divided into two subgroups based on sacrifice dates. The rats were sacrificed at intervals of 3 and 6 weeks after the surgery to extract their right femurs for radiography and biomechanical and histological analyses, and the results were analyzed using standard statistical methods. Radiographic analyses showed greater callus formation in the LLLT and WBV groups than in control group at both 3 (P?<?0.05 and P?<?0.001, respectively) and 6 weeks after surgery (P?<?0.05 and P?<?0.05, respectively). Histological evaluations showed a higher amount of new bone formation and better maturity in the LLLT and WBV groups than the control groups at 3 and 6 weeks after surgery. Biomechanical tests showed that the maximum force at fracture in the LLLT (P?<?0.05 in 3 weeks and P?<?0.05 in 6 weeks) and WBV (P?<?0.001 in 3 weeks and P?<?0.05 in 6 weeks) groups was greater than that in the control groups at both time intervals. But a combination of laser and vibration therapy, LV, did not show a positive interaction on bone fracture healing process. The biostimulation effects of PBM or LLLT and of low-amplitude high-frequency WBV both had a positive impact on bone healing process, for critical size defects in the presence of a stainless steel implant. But their combination, i.e., low-level laser therapy and low-amplitude high-frequency whole body vibration (LV), interestingly did not accelerate the fractured bone healing process.     

Effects of low-level laser therapy on bone regeneration of the midpalatal suture after rapid maxillary expansion

This study evaluated the effect of low-level laser therapy (LLLT) on bone regeneration at the midpalatal suture (MPS) after rapid maxillary expansion (RME), using cone beam computed tomography. Fourteen 8–14-year-old patients with transverse maxillary deficiency underwent RME with a Hyrax-type expander activated with one full turn after installation and two half turn daily activations until achieving overcorrection. Patients were randomly assigned to either a control group (RME alone, n?=?4) or an experimental group (n?=?10) in which RME was followed by 12 LLLT sessions (GaAlAs, p?=?70 mW, λ?=?780 nm, Ø?=?0.04 cm²). Two tomographic images of the MPS were obtained—T0, after disjunction and T1, after 4 months. Bone regeneration was evaluated by measuring the optical density (OD) on the tomographic images using InVivo Dental 5.0 software. Data were analyzed by the paired Student’s t test (α?=?0.05 %). A statistically significant difference between T0 and T1 OD values was observed in the laser-treated group (p?=?0.00), but this difference was not significant in the control group (p?=?0.20). Intergroup comparison of OD values at T1 revealed higher OD in the laser-treated group (p?=?0.05). In conclusion, LLLT had a positive influence on bone regeneration of the midpalatal suture by accelerating the repair process.     

Effects of low-level laser therapy on performance,inflammatory markers,and muscle damage in young water polo athletes: a double-blind,randomized, placebo-controlled study

This study aimed to evaluate the effects of 5 days of 810-nm low-level laser therapy (LLLT) intervention on inflammatory and muscle damage markers and performance in young water polo players. Twenty young male water polo players participated in the study, which was designed as a randomized, double-blinded, placebo-controlled trial. Active LLLT or an identical placebo LLLT were delivered to eight points on the adductor muscle region immediately after each training day. Performance was measured by a 200-m maximal swimming (P200) and a 30-s crossbar jump test (30CJ) which was performed every day before training, and blood samples were drawn pre and post the final LLLT intervention to measure interleukins (IL) and muscle damage markers. There was no significant change in the P200 exercise in the LLLT group compared with the placebo group but there was a moderate improvement in the 30CJ (8.7?±?2.6 %). IL-1β and tumor necrosis factor-alpha presented increased (P?<?0.016) concentration within group 48 h after the last LLLT intervention compared to pre, 0, and 24 h, but did not differ between groups. IL-10 increased over time in the placebo group and reached a moderate effect compared to the LLLT group. The creatine kinase decreased significantly (P?=?0.049) over the time within the LLLT treatment group, but there was no significant change in lactate dehydrogenase (P?=?0.150). In conclusion, LLLT resulted in a non-significant, but small to moderate effect on inflammatory and muscle damage markers and a moderate effect on performance in water polo players. In addition, the lack of positive results could be due to the small area covered by irradiation and this should be considered in future studies.     

Cognitive enhancement by transcranial laser stimulation and acute aerobic exercise

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation and acute aerobic exercise on the same cognitive tasks. We examined whether transcranial infrared laser stimulation of the prefrontal cortex, acute high-intensity aerobic exercise, or the combination may enhance performance in sustained attention and working memory tasks. Sixty healthy young adults were randomly assigned to one of the following four treatments: (1) low-level laser therapy (LLLT) with infrared laser to two forehead sites while seated (total 8 min, 1064 nm continuous wave, 250 mW/cm², 60 J/cm² per site of 13.6 cm²); (2) acute exercise (EX) of high-intensity (total 20 min, with 10-min treadmill running at 85–90 % VO₂max); (3) combined treatment (LLLT + EX); or (4) sham control (CON). Participants were tested for prefrontal measures of sustained attention with the psychomotor vigilance task (PVT) and working memory with the delayed match-to-sample task (DMS) before and after the treatments. As compared to CON, both LLLT and EX reduced reaction time in the PVT [F(1.56)?=?4.134, p?=?0.01, η ² ?=?0.181] and increased the number of correct responses in the DMS [F(1.56)?=?4.690, p?=?0.005, η ² ?=?0.201], demonstrating a significant enhancing effect of LLLT and EX on cognitive performance. LLLT + EX effects were similar but showed no significantly greater improvement on PVT and DMS than LLLT or EX alone. The transcranial infrared laser stimulation and acute aerobic exercise treatments were similarly effective for cognitive enhancement, suggesting that they augment prefrontal cognitive functions similarly.     

Effect of prior application with and without post-injury treatment with low-level laser on the modulation of key proteins in the muscle repair process

The aim of the present study was to evaluate the effects of LLLT prior to muscle injury with and without post-injury irradiation on the expression of isoforms of myosin heavy chain (MyHC), calcineurin (CaN), and myostatin during the repair process. Wistar rats were divided into five groups: control (n?=?7); injury (n?=?21); LLLT + injury (n?=?21); injury + LLLT (n?=?21), and LLLT + injury + LLLT (n?=?21). Cryoinjury was performed on the tibialis anterior (TA) muscle. The injured groups were euthanized at 3, 7, and 14 days after injury. LLLT was performed using an infrared laser (780 nm) with the following parameters: 10 J/cm², 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. At the end of each period, the TA muscle was removed for the analysis of MyHC, CaN, and myostatin gene expression using real-time PCR. The data were tested statistically by Kruskal-Wallis with Dunn’s post hoc test (p?<?0.05). The results demonstrated that prior irradiation reduced the mRNA expression of all proteins at 3 days. Post irradiation reduced the mRNA expression of MyHC-1, MyHC-2a, MyHC-2b, and CaN at 7 days. Prior irradiation combined with post-injury irradiation reduced the mRNA expression of MyHC-2x and CaN at 14 days and increased the mRNA expression of myostatin in the same period. In conclusion, different protocols of photobiomodulation can modulate the expression of the different isoforms of MyHC, CaN, and myostatin during the repair process. It is noteworthy that the combination of the prior and post-injury irradiation was the protocol that most promoted changes in the final phase of the repair process.     

Photobiomodulation therapy protects skeletal muscle and improves muscular function of mdx mice in a dose-dependent manner through modulation of dystrophin

This study aimed to analyze the protective effects of photobiomodulation therapy (PBMT) with combination of low-level laser therapy (LLLT) and light emitting diode therapy (LEDT) on skeletal muscle tissue to delay dystrophy progression in mdx mice (DMD ^mdx ). To this aim, mice were randomly divided into five different experimental groups: wild type (WT), placebo-control (DMD ^mdx ), PBMT with doses of 1 J (DMD ^mdx ), 3 J (DMD ^mdx ), and 10 J (DMD ^mdx ). PBMT was performed employing a cluster probe with 9 diodes (1 x 905nm super-pulsed laser diode; 4 x 875nm infrared LEDs; and 4 x 640nm red LEDs, manufactured by Multi Radiance Medical®, Solon - OH, USA), 3 times a week for 14 weeks. PBMT was applied on a single point (tibialis anterior muscle—bilaterally). We analyzed functional performance, muscle morphology, and gene and protein expression of dystrophin. PBMT with a 10 J dose significantly improved (p?<?0.001) functional performance compared to all other experimental groups. Muscle morphology was improved by all PBMT doses, with better outcomes with the 3 and 10 J doses. Gene expression of dystrophin was significantly increased with 3 J (p?<?0.01) and 10 J (p?<?0.01) doses when compared to placebo-control group. Regarding protein expression of dystrophin, 3 J (p?<?0.001) and 10 J (p?<?0.05) doses also significantly showed increase compared to placebo-control group. We conclude that PBMT can mainly preserve muscle morphology and improve muscular function of mdx mice through modulation of gene and protein expression of dystrophin. Furthermore, since PBMT is a non-pharmacological treatment which does not present side effects and is easy to handle, it can be seen as a promising tool for treating Duchenne’s muscular dystrophy.     

Increase in the nitric oxide release without changes in cell viability of macrophages after laser therapy with 660 and 808 nm lasers

The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) with different parameters and wavelengths on nitric oxide (NO) release and cell viability. Irradiation was performed with Ga-Al-As laser, continuous mode and wavelengths of 660 and 808 nm at different energy and power densities. For each wavelength, powers of 30, 50, and 100 mW and times of 10, 30, and 60 s were used. NO release was measured using Griess reaction, and cell viability was evaluated by mitochondrial reduction of bromide 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to formazan. LLLT promoted statistically significant changes in NO release and MTT value only at the wavelength of 660 nm (p?<?0.05). LLLT also promoted an increase in the NO release and cell viability when the energy densities 64 (p?=?0.04) and 214 J/cm² (p?=?0.012), respectively, were used. LLLT has a significant impact on NO release without affecting cell viability, but the significance of these findings in the inflammatory response needs to be further studied.     

Effects of oral motor exercises and laser therapy on chronic temporomandibular disorders: a randomized study with follow-up

This study investigated the efficacy of combining low-level laser therapy (LLLT) with oral motor exercises (OM-exercises) for rehabilitation of patients with chronic temporomandibular disorders (TMDs). Eighty-two patients with chronic TMD and 20 healthy subjects (control group) participated in the study. Patients were randomly assigned to treatment groups: GI (LLLT?+?OM exercises), GII (orofacial myofunctional therapy—OMT—which contains pain relief strategies and OM-exercises), and GIII (LLLT placebo?+?OM-exercises) and GIV (LLLT). LLLT (AsGaAl; 780-nm wavelength; average power of 60 mW, 40 s, and 60?±?1.0 J/cm²) was used to promote analgesia, while OM-exercises were used to reestablish the orofacial functions. Evaluations at baseline (T1), after treatment immediate (T2), and at follow-up (T3) were muscle and joint tenderness to palpation, TMD severity, and orofacial myofunctional status. There was a significant improvement in outcome measures in all treated groups with stability at follow-up (Friedman test, P?<?0.05), but GIV did not show difference in orofacial functions after LLLT (P?>?0.05). Intergroup comparisons showed that all treated groups had no difference in tenderness to palpation of temporal muscle compared to GC at follow-up (Kruskal-Wallis test, P?<?0.01). Moreover, GI, GII, and GIII showed no difference from GC in orofacial functional condition (T2 and T3) while they differed significantly from GIV (P?<?0.01). In conclusion, LLLT combined with OM-exercises was more effective in promoting TMD rehabilitation than LLLT alone was. Similar treatment results were verified with the OMT protocol.     

Long-term low-level laser therapy promotes an increase in maximal oxygen uptake and exercise performance in a dose-dependent manner in Wistar rats

The use of low-level laser therapy (LLLT) represents a new intervention modality that has been explored to enhance exercise performance. The aim of this study was to evaluate the influence of LLLT (GaAIAs—850 nm) at different doses on VO_2max and on exercise performance in rats. Male Wistar rats were divided into three groups: “placebo” rats (P-LLLT, n?=?10), rats at a dose of 0.315 J per treatment point of LLLT (8.7 J/cm²-LLLT, n?=?10), and rats at a dose of 2.205 J per treatment point of LLLT (61.2 J/cm²-LLLT, n?=?10). The LLLT was applied bilaterally at the biceps femoris, gluteus, lateral and medial gastrocnemius, iliopsoas, and adductor longus muscles. One spot in each muscle belly was applied, with a sum of 12 spots in each rat, once a day, for 10 days. All animals performed the maximal exercise test (ET) at a metabolic treadmill for rats, with simultaneous gas analysis. The distance covered was measured during ET, before and after the conclusion of the LLLT protocol. The data were compared by a repeated measures two-way ANOVA followed by the Student-Newman-Keuls post hoc tests (p?<?.05). The 61.2 J/cm²-LLLT group increased VO_2basal (~40 %), VO_2max (~24 %), VCO_2max (~17 %), and distance covered (~34 %) after LLLT application on the skeletal muscle. No significant results were found comparing before and after conditions for the studied variables considering P-LLLT and 8.7 J/cm²-LLLT groups. The LLLT promoted in a dose-dependent manner an increase in oxygen consumption uptake and a performance increment of male Wistar rats.     

The effect of low-level laser therapy on oxidative stress and functional fitness in aged rats subjected to swimming: an aerobic exercise

The aim of the present study was to determine whether low-level laser therapy (LLLT) in conjunction with aerobic training interferes with oxidative stress, thereby influencing the performance of old rats participating in swimming. Thirty Wistar rats (Norvegicus albinus) (24 aged and six young) were tested. The older animals were randomly divided into aged-control, aged-exercise, aged-LLLT, aged-LLLT/exercise, and young-control. Aerobic capacity (VO₂max^0.75) was analyzed before and after the training period. The exercise groups were trained for 6 weeks, and the LLLT was applied at 808 nm and 4 J energy. The rats were euthanized, and muscle tissue was collected to analyze the index of lipid peroxidation thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities. VO₂ ^0.75max values in the aged-LLLT/exercise group were significantly higher from those in the baseline older group (p <0.01) and the LLLT and exercise group (p <0.05). The results indicate that the activities of CAT, SOD, and GPx were higher and statistically significant (p <0.05) in the LLLT/exercise group than those in the LLLT and exercise groups. Young animals presented lesser and statistically significant activities of antioxidant enzymes compared to the aged group. The LLLT/exercise group and the LLLT and exercise group could also mitigate the concentration of TBARS (p?>?0.05). Laser therapy in conjunction with aerobic training may reduce oxidative stress, as well as increase VO2 ^0.75max, indicating that an aerobic exercise such as swimming increases speed and improves performance in aged animals treated with LLLT.