Immediate responses of multi-focal low level laser therapy on quadriceps in knee osteoarthritis patients.

Low-level laser therapy (LLLT) applying on knee osteoarthritis (OA) patients has shown positive outcomes in analgesic effect and functional recovery. However, few studies applied such therapy on large area of quadriceps muscle in these patients. The aim of this study was to evaluate immediate effect of multi-focal LLLT on quadriceps of knee OA patients in pain and functional performance. Fifty-one participants with knee OA were enrolled and evaluated before (T1) and immediately after intervention (T2) by knee joint pain in numeric rating scale (NRS), walking speed, timed five-chair stands, and quadriceps strength by isokinetic dynamometer. Intervention with two multi-focal Gallium-Aluminum-Arsenide laser devices, each device with 36 laser diodes (wavelength 808 ± 10 nm, continuous, mean power 50 mW, 30 minutes), applied simultaneously over bilateral quadriceps with a total dose of 180 J for each thigh. The multi-focal LLLT significantly improved knee joint pain as measured by the NRS (54% reduction), timed five-chair stands, and walking speed (P < .05). Knee extensor strength also increased in terms of peak torque and force of concentric and eccentric contraction as measured by isokinetic dynamometer (P < .05). In conclusion, single-session multi-focal LLLT on quadriceps in knee OA patients has immediate beneficial effect on knee pain reduction, quadriceps strengthening and functional performance recovery. Long-term effect requires further investigation. Multi-focal LLLT on quadriceps might serve as an alternative non-invasive treatment option in these patients.

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

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

Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial.

Promising effects of phototherapy on markers of exercise-induced muscle damage has been already demonstrated in constant load or isokinetic protocols. However, its effects on more functional situations, such as plyometric exercises, and when is the best moment to apply this treatment (pre- or post-exercise) remain unclear. Therefore, the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before or after plyometric exercise on quadriceps muscle damage markers. A randomized, double-blinded, placebo-controlled trial was conducted with 24 healthy men, 12 at pre-exercise treatment group and 12 at post-exercise treatment group. Placebo and LLLT (810 nm, 200 mW per diode, 6 J per diode, 240 J per leg) were randomly applied on right/left knee extensor muscles of each volunteer before/after a plyometric exercise protocol. Muscular echo intensity (ultrasonography images), soreness (visual analogue scale - VAS), and strength impairment (maximal voluntary contraction - MVC) were assessed at baseline, 24, 48, and 72 h post-exercise. Legs treated with LLLT before or after exercise presented significantly smaller increments of echo intensity (values up to 1 %) compared to placebo treatments (increased up to ∼7 %). No significant treatment effect was found for VAS and MVC, although a trend toward better results on LLLT legs have been found for VAS (mean values up to 30 % lesser than placebo leg). In conclusion, LLLT applied before or after plyometric exercise reduces the muscle echo intensity response and possibly attenuates the muscle soreness. However, these positive results were not observed on strength impairment.

Effects of photobiomodulation on the fatigue level in elderly women: an isokinetic dynamometry evaluation.

Aging is responsible by a series of morphological and functional modifications that lead to a decline of muscle function, particularly in females. Muscle tissue in elderly people is more susceptible to fatigue and, consequently, to an increased inability to maintain strength and motor control. In this context, therapeutic approaches able of attenuating muscle fatigue have been investigated. Among these, the photobiomodulation demonstrate positive results to interacts with biological tissues, promoting the increase in cell energy production. Thus, the aim of this study was to investigate the effects of photobiomodulation (808 nm, 250 J/cm(2), 100 mW, 7 J each point) in the fatigue level and muscle performance in elderly women. Thirty subjects entered a crossover randomized double-blinded placebo-controlled trial. Photobiomodulation was delivered on the rectus femoris muscle of the dominant limb immediately before the fatigue protocol. In both sessions, peripheral muscle fatigue was analyzed by surface electromyography (EMG) and blood lactate analysis. Muscle performance was evaluated using an isokinetic dynamometer. The results showed that photobiomodulation was able of reducing muscle fatigue by a significant increase of electromyographic fatigue index (EFI) (p = 0.047) and decreasing significantly lactate concentration 6 min after the performance of the fatigue protocol (p = 0. 0006) compared the placebo laser session. However, the photobiomodulation was not able of increasing muscle performance measured by the isokinetic dynamometer. Thus, it can be conclude that the photobiomodulation was effective in reducing fatigue levels. However, no effects of photobiomodulation on muscle performance was observed.

Immediate effects of low-intensity laser (808 nm) on fatigue and strength of spastic muscle.

The cerebrovascular accident (CVA), high-impact disease II, affects the basic functions of the limbs, leading to changes of sensory, language, and motor functions. The search for resources that minimize the damage caused by this disease grows every day. The clinical use of low-intensity laser therapy (LILT) has provided major breakthroughs in the treatment of muscular disorders and prevention of muscle fatigue. Thus, the objective of the present study is to analyze the answers and immediate adaptations of the rectus femoris and vastus medialis of spastic hemiparetic patients, facing the increase in peak torque and triggering muscle fatigue, after application of LILT. Double-blind clinical trials were conducted with 15 volunteers post-CVA with spasticity, of both genders, between 40 and 80 years old. To this end, the volunteers went through three consecutive stages of rating (control, placebo, and laser). All performed tests of isometric contraction on the patient's hemiparetic side. Significant differences were observed with regard to the increase in muscle performance (p = 0.0043) and the reduction in blood lactate concentration (p < 0.0001) of the post-LILT muscles. The LILT (diode laser, l100 mW 808 nm, 4.77 J/cm(2)/point, 40 s/AP) can be employed during and after spastic muscle-strengthening exercises, contributing to the improvement of motor function of the patient. After application of LILT, we found increased torque as well as decreased in lactate level in patients with spasticity.

Phototherapy in skeletal muscle performance and recovery after exercise: effect of combination of super-pulsed laser and light-emitting diodes.

Recent studies with phototherapy have shown positive results in enhancement of performance and improvement of recovery when applied before exercise. However, several factors still remain unknown such as therapeutic windows, optimal treatment parameters, and effects of combination of different light sources (laser and LEDs). The aim of this study was to evaluate the effects of phototherapy with the combination of different light sources on skeletal muscle performance and post-exercise recovery, and to establish the optimal energy dose. A randomized, double-blinded, placebo-controlled trial with participation of 40 male healthy untrained volunteers was performed. A single phototherapy intervention was performed immediately after pre-exercise (baseline) maximum voluntary contraction (MVC) with a cluster of 12 diodes (4 of 905 nm lasers-0.3125 mW each, 4 of 875 nm LEDs-17.5 mW each, and 4 of 670 nm LEDs-15 mW each- manufactured by Multi Radiance Medical™) and dose of 10, 30, and 50 J or placebo in six sites of quadriceps. MVC, delayed onset muscle soreness (DOMS), and creatine kinase (CK) activity were analyzed. Assessments were performed before, 1 min, 1, 24, 48, 72, and 96 h after eccentric exercise protocol employed to induce fatigue. Phototherapy increased (p < 0.05) MVC was compared to placebo from immediately after to 96 h after exercise with 10 or 30 J doses (better results with 30 J dose). DOMS was significantly decreased compared to placebo (p < 0.05) with 30 J dose from 24 to 96 h after exercise, and with 50 J dose from immediately after to 96 h after exercise. CK activity was significantly decreased (p < 0.05) compared to placebo with all phototherapy doses from 1 to 96 h after exercise (except for 50 J dose at 96 h). Pre-exercise phototherapy with combination of low-level laser and LEDs, mainly with 30 J dose, significantly increases performance, decreases DOMS, and improves biochemical marker related to skeletal muscle damage.

Effects of pre- or post-exercise low-level laser therapy (830 nm) on skeletal muscle fatigue and biochemical markers of recovery in humans: double-blind placebo-controlled trial.

OBJECTIVES: The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before and after exercise on quadriceps muscle performance, and to evaluate the changes in serum lactate and creatine kinase (CK) levels. METHODS: The study was randomized, double blind, and placebo controlled. PATIENTS: A sample of 27 healthy volunteers (male soccer players) were divided into three groups: placebo, pre-fatigue laser, and post-fatigue laser. The experiment was performed in two sessions, with a 1 week interval between them. Subjects performed two sessions of stretching followed by blood collection (measurement of lactate and CK) at baseline and after fatigue of the quadriceps by leg extension. LLLT was applied to the femoral quadriceps muscle using an infrared laser device (830 nm), 0.0028 cm(2) beam area, six 60 mW diodes, energy of 0.6 J per diode (total energy to each limb 25.2 J (50.4 J total), energy density 214.28 J/cm(2), 21.42 W/cm(2) power density, 70 sec per leg. We measured the time to fatigue and number and maximum load (RM) of repetitions tolerated. Number of repetitions and time until fatigue were primary outcomes, secondary outcomes included serum lactate levels (measured before and 5, 10, and 15 min after exercise), and CK levels (measured before and 5 min after exercise). RESULTS: The number of repetitions (p=0.8965), RM (p=0.9915), and duration of fatigue (p=0.8424) were similar among the groups. Post-fatigue laser treatment significantly decreased the serum lactate concentration relative to placebo treatment (p<0.01) and also within the group over time (after 5 min vs. after 10 and 15 min, p<0.05 both). The CK level was lower in the post-fatigue laser group (p<0.01). CONCLUSIONS: Laser application either before or after fatigue reduced the post-fatigue concentrations of serum lactate and CK. The results were more pronounced in the post-fatigue laser group.

Acute effects of light emitting diodes therapy (LEDT) in muscle function during isometric exercise in patients with chronic obstructive pulmonary disease: preliminary results of a randomized controlled trial.

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to early muscle fatigue. Light-emitting diodes therapy (LEDT) has been used to minimize muscle fatigue in athletes and healthy subjects. The aim of this study is to investigate the acute effects of LEDT on muscle fatigue and perception of effort in patients with COPD during isometric endurance test of the quadriceps femoris (QF). Ten patients (VEF1 50 ± 13% of predicted) underwent a single LEDT and sham application, 48 h apart, in a randomized crossover design. The LEDT and sham were applied in three localized areas of the QF (rectus femoris, vastus lateralis, and vastus medialis). Before and after exposure to LEDT and sham, the patients performed an isometric endurance test (60 % of the maximum voluntary isometric contraction), until the limit of tolerance concomitant to surface electromyography recording (median frequency as mean outcome). The slope obtained from linear regression analysis of the median frequency (MF) over endurance time was also used as an endurance index. Endurance time increased significantly after exposure to LEDT (from 26 ± 2 to 53 ± 5 s) as compared to sham (from 23 ± 3 to 30 ± 4 s) (F = 64, P = 0.0001). A greater decline in MF was observed during isometric endurance test after sham, compared to LEDT (F = 14.6, P = 0.004). The slope of the MF over time was lower post-LEDT compared to post-sham (-0.7 ± 0.3 vs. -1.5 ± 0.8; P = 0.004). The dyspnea score corrected for endurance time was lower post-LEDT (P = 0.008) but similar for fatigue both post-LEDT and post-sham. A single application of LEDT minimizes muscle fatigue and increases isometric endurance time.

Effects of low level laser therapy (808 nm) on physical strength training in humans.

Recent studies have investigated whether low level laser therapy (LLLT) can optimize human muscle performance in physical exercise. This study tested the effect of LLLT on muscle performance in physical strength training in humans compared with strength training only. The study involved 36 men (20.8±2.2 years old), clinically healthy, with a beginner and/or moderate physical activity training pattern. The subjects were randomly distributed into three groups: TLG (training with LLLT), TG (training only) and CG (control). The training for TG and TLG subjects involved the leg-press exercise with a load equal to 80% of one repetition maximum (1RM) in the leg-press test over 12 consecutive weeks. The LLLT was applied to the quadriceps muscle of both lower limbs of the TLG subjects immediately after the end of each training session. Using an infrared laser device (808 nm) with six diodes of 60 mW each a total energy of 50.4 J of LLLT was administered over 140 s. Muscle strength was assessed using the 1RM leg-press test and the isokinetic dynamometer test. The muscle volume of the thigh of the dominant limb was assessed by thigh perimetry. The TLG subjects showed an increase of 55% in the 1RM leg-press test, which was significantly higher than the increases in the TG subjects (26%, P = 0.033) and in the CG subjects (0.27%, P < 0.001). The TLG was the only group to show an increase in muscle performance in the isokinetic dynamometry test compared with baseline. The increases in thigh perimeter in the TLG subjects and TG subjects were not significantly different (4.52% and 2.75%, respectively; P = 0.775). Strength training associated with LLLT can increase muscle performance compared with strength training only.