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.
The aim of the present study was to determine the effect of low-level laser therapy (LLLT) on the expression of TNF-a and TGF-ß in the tibialis anterior muscle of rats following cryoinjury. Muscle regeneration involves cell proliferation, migration and differentiation and is regulated by growth factors and cytokines. A growing body of evidence suggests that LLLT promotes skeletal muscle regeneration by reducing the duration of acute inflammation and accelerating tissue repair. Adult male Wistar rats (n = 35) were randomly divided into three groups: control group (no lesion, untreated, n = 5), cryoinjury without LLLT group (n = 15), and cryoinjury with LLLT group (n = 15). The injured region was irradiated three times a week using an AlGaInP laser (660 nm; beam spot 0.04 cm(2), output power 20 mW, power density 500 mW/cm(2), energy density 5 J/cm(2), exposure time 10 s). Muscle remodeling was evaluated at 1, 7 and 14 days (long-term) following injury. The muscles were removed and total RNA was isolated using TRIzol reagent and cDNA synthesis. Real-time polymerase chain reactions were performed using TNF-a and TGF-ß primers; GAPDH was used to normalize the data. LLLT caused a decrease in TNF-a mRNA expression at 1 and 7 days following injury and in TGF-ß mRNA expression at 7 days following cryoinjury in comparison to the control group. LLLT modulated cytokine expression during short-term muscle remodeling, inducing a decrease in TNF-a and TGF-ß.
The purpose of the present study was to determine the effect of low level laser therapy (LLLT) treatment before knee extensor eccentric exercise on indirect markers of muscle damage. Thirty-six healthy men were randomized in LLLT group (n = 18) and placebo group (n = 18). After LLLT or placebo treatment, subjects performed 75 maximal knee extensors eccentric contractions (five sets of 15 repetitions; velocity = 60 degrees seg(-1); range of motion = 60 degrees ). Muscle soreness (visual analogue scale-VAS), lactate dehydrogenase (LDH) and creatine kinase (CK) levels were measured prior to exercise, and 24 and 48 h after exercise. Muscle function (maximal voluntary contraction-MVC) was measured before exercise, immediately after, and 24 and 48 h post-exercise. Groups had no difference on kineanthropometric characteristics and on eccentric exercise performance. They also presented similar baseline values of VAS (0.00 mm for LLLT and placebo groups), LDH (LLLT = 186 IU/l; placebo = 183 IU/l), CK (LLLT = 145 IU/l; placebo = 155 IU/l) and MVC (LLLT = 293 Nm; placebo = 284 Nm). VAS data did not show group by time interaction (P = 0.066). In the other outcomes, LLLT group presented (1) smaller increase on LDH values 48 h post-exercise (LLLT = 366 IU/l; placebo = 484 IU/l; P = 0.017); (2) smaller increase on CK values 24 h (LLLT = 272 IU/l; placebo = 498 IU/l; P = 0.020) and 48 h (LLLT = 436 IU/l; placebo = 1328 IU/l; P < 0.001) post-exercise; (3) smaller decrease on MVC immediately after exercise (LLLT = 189 Nm; placebo = 154 Nm; P = 0.011), and 24 h (LLLT = 249 Nm; placebo = 205 Nm; P = 0.004) and 48 h (LLLT = 267 Nm; placebo = 216 Nm; P = 0.001) post-exercise compared with the placebo group. In conclusion, LLLT treatment before eccentric exercise was effective in terms of attenuating the increase of muscle proteins in the blood serum and the decrease in muscle force.
Contrary to the common belief that checking among young hockey players causes the most injuries, an online study in the British Journal of Sports Medicine found 66% of their overall injuries were due to accidents, including players hitting the boards or goal posts, colliding with other players, or being hit by a puck.
The study, conducted by researchers at the University of Buffalo, which examined injury rates for 3,000 boys ages four to 18 years for a 5-year period — for a total of 13,292 players years, is the largest and most comprehensive analysis to date of young hockey players, according to a University of Buffalo press release.
“There is an image of body checking as a form of violence that is condoned by the game of hockey. However, this study found that body checking did not account for a large proportion of injuries. Perhaps as important, body checking did not lead to a rise in intentional injuries,” Barry Willer, PhD, a University of Buffalo professor of psychiatry and rehabilitation sciences and senior author of the study, stated in the release.
Injuries during play, practice
Willer and colleagues studied participants in the Burlington, Ontario youth hockey program, comparing injury rates overall for three levels of competition: “house leagues,” where no body checking occurs; “select,” in which players age 11 years and older can check; and “representative,” which consists of the most skilled players who are allowed to body check starting at age 9.
Additionally, researchers examined injury rates as the level of competition and age of the players increased and the differences in injury rates in practices vs. games. They only included data for injuries that kept a player off the ice at least 24 hours.
The analysis showed that three times more accidental injuries (90) than injuries from body checking (30) occurred in the “house leagues” and 28 injuries, the fewest among the competition levels, occurred in the “select” level. In the “representative” league, among 96 injuries reported, 59% were unintentional. That league’s 39 intentional injuries, however, were the highest of all the categories.
Skill vs. injury rate “Game injuries were much more frequent among the highly skilled players on representative teams,” Willer stated, which correlated with the researchers’ predictions.
“The study does suggest that, regardless of whether young players are allowed to body check, unintentional contact with the board, the ice or other players are important sources of serious intended injury,” he noted.
A study of injuries associated with body checking in youth hockey in the Journal of the American Medical Association found a threefold increased risk of game-related injuries among youth hockey leagues allowing checking vs. leagues that disallowed it.
STUDY DESIGN: Randomized crossover double-blinded placebo-controlled trial.
OBJECTIVE: To investigate if low level laser therapy (LLLT) can affect biceps muscle performance, fatigue development, and biochemical markers of post-exercise recovery.
BACKGROUND: Cell and animal studies have suggested that LLLT can reduce oxidative stress and inflammatory responses in muscle tissue. But it remains uncertain whether these findings can translate into humans in sport and exercise situations.
METHODS: Nine healthy male volleyball players participated in the study. They received either active LLLT (cluster probe with 5 laser diodes, l=810 nm, 200 mW power output, 30 seconds of irradiation, applied in 2 locations over the biceps of the non-dominant arm, 60 J of total energy) or placebo LLLT using an identical cluster probe. The intervention or placebo were applied 3 minutes before the performance of exercise. All subjects performed voluntary elbow flexion repetitions with a workload of 75% of their maximal voluntary contraction force (MVC) until exhaustion.
RESULTS: Active LLLT increased the number of repetitions by 14.5% (mean of 39.56, SD +/- 4.33 versus 34.56 +/- 5.64, p=0.037) and the elapsed time before exhaustion by 8.0% (p=0.034), when compared to the placebo treatment. The biochemical markers also indicated that recovery may be positively affected by LLLT as indicated by post-exercise blood lactate levels (p < 0.01), Creatine Kinase (CK) activity (p=0.017), and C-Reactive Protein (CRP) levels (p=0.047) showing a faster recovery with LLLT application prior to the exercise.
CONCLUSION: We conclude that pre-exercise irradiation of the biceps with an LLLT dose of 6 J per application location, applied in 2 locations, increased endurance for repeated elbow flexion against resistance, and decreased post-exercise levels of blood lactate, CK, and CRP.
BACKGROUND AND OBJECTIVES: There are some indications that low-level laser therapy (LLLT) may delay the development of skeletal muscle fatigue during high-intensity exercise. There have also been claims that LED cluster probes may be effective for this application however there are differences between LED and laser sources like spot size, spectral width, power output, etc. In this study we wanted to test if light emitting diode therapy (LEDT) can alter muscle performance, fatigue development and biochemical markers for skeletal muscle recovery in an experimental model of biceps humeri muscle contractions.
STUDY DESIGN/MATERIALS AND METHODS: Ten male professional volleyball players (23.6 [SD +/-5.6] years old) entered a randomized double-blinded placebo-controlled crossover trial. Active cluster LEDT (69 LEDs with wavelengths 660/850 nm, 10/30 mW, 30 seconds total irradiation time, 41.7 J of total energy irradiated) or an identical placebo LEDT was delivered under double-blinded conditions to the middle of biceps humeri muscle immediately before exercise. All subjects performed voluntary biceps humeri contractions with a workload of 75% of their maximal voluntary contraction force (MVC) until exhaustion.
RESULTS: Active LEDT increased the number of biceps humeri contractions by 12.9% (38.60 [SD +/-9.03] vs. 34.20 [SD +/-8.68], P = 0.021) and extended the elapsed time to perform contractions by 11.6% (P = 0.036) versus placebo. In addition, post-exercise levels of biochemical markers decreased significantly with active LEDT: Blood Lactate (P = 0.042), Creatine Kinase (P = 0.035), and C-Reative Protein levels (P = 0.030), when compared to placebo LEDT.
CONCLUSION: We conclude that this particular procedure and dose of LEDT immediately before exhaustive biceps humeri contractions, causes a slight delay in the development of skeletal muscle fatigue, decreases post-exercise blood lactate levels and inhibits the release of Creatine Kinase and C-Reative Protein. Lasers Surg.
This report documents retrospectively a case of Posterior Interosseous Neuropathy (PIN) occurring in an elite baseball pitcher experiencing a deep ache in the radial aspect of the forearm and altered sensation in the dorsum of the hand on the throwing arm during his pitching motion. The initial clinical goal was to control for inflammation to the nerve and muscle with active rest, microcurrent therapy, low-level laser therapy, and cessation of throwing. Minimizing mechanosensitivity at the common extensor region of the right elbow and PIN, was achieved by employing the use of myofascial release and augmented soft tissue mobilization techniques. Neurodynamic mobilization technique was also administered to improve neural function. Implementation of a sport specific protocol for the purposes of maintaining throwing mechanics and overall conditioning was utilized. Successful resolution of symptomatology and return to pre-injury status was achieved in 5 weeks. A review of literature and an evidence-based discussion for the differential diagnoses, clinical examination, diagnosis, management and rehabilitation of PIN is presented.
OBJECTIVE: The purpose of this study was to investigate the effects of phototherapy on delayed onset muscle soreness (DOMS) as measured using the Visual Analog Scale (VAS), McGill Pain Questionnaire, Resting Angle (RANG), and girth measurements.
BACKGROUND DATA: Previous research has failed to prove the beneficial effects of phototherapy on DOMS.
METHODS: This was a randomized double-blind controlled study with 27 subjects (18-35 years) assigned to one of three groups. The experimental group received 8 J/cm2 of phototherapy each day for five consecutive days using super luminous diodes with wavelengths of 880 and visible diodes of 660 nm at three standardized sites over the musculotendinous junction of the bicep. The sham group received identical treatment from a dummy cluster. The controls did not receive treatment. The study was completed over five consecutive days: on day one baseline measurements of RANG and upper arm girths were recorded prior to DOMS induction. On days 2-5, RANG, girth, and pain were assessed using VAS and the McGill Pain Questionnaire.
RESULTS: The experimental group exhibited a significant decrease in pain associated with DOMS compared to the control (p=0.01) and sham groups (p=0.03) based upon the VAS at the 48-h period. The McGill Pain Questionnaire showed a significant difference in pain scores at the 48-h period between the experimental and the sham groups (p=0.01). There were no significant differences day to day and between the groups with respect to girth and RANG.
CONCLUSION: The results of this study provide scientific evidence that phototherapy as used in this study provides a beneficial effect to patients who may experience DOMS after a novel exercise session.
PMID: 16875447 [PubMed - indexed for MEDLINE]
OBJECTIVE: To investigate if development of skeletal muscle fatigue during repeated voluntary biceps contractions could be attenuated by low-level laser therapy (LLLT).
BACKGROUND DATA: Previous animal studies have indicated that LLLT can reduce oxidative stress and delay the onset of skeletal muscle fatigue.
MATERIALS AND METHODS: Twelve male professional volleyball players were entered into a randomized double-blind placebo-controlled trial, for two sessions (on day 1 and day 8) at a 1-wk interval, with both groups performing as many voluntary biceps contractions as possible, with a load of 75% of the maximal voluntary contraction force (MVC). At the second session on day 8, the groups were either given LLLT (655 nm) of 5 J at an energy density of 500 J/cm2 administered at each of four points along the middle of the biceps muscle belly, or placebo LLLT in the same manner immediately before the exercise session. The number of muscle contractions with 75% of MVC was counted by a blinded observer and blood lactate concentration was measured.
RESULTS: Compared to the first session (on day 1), the mean number of repetitions increased significantly by 8.5 repetitions (+/- 1.9) in the active LLLT group at the second session (on day 8), while in the placebo LLLT group the increase was only 2.7 repetitions (+/- 2.9) (p = 0.0001). At the second session, blood lactate levels increased from a pre-exercise mean of 2.4 mmol/L (+/- 0.5 mmol/L), to 3.6 mmol/L (+/- 0.5 mmol/L) in the placebo group, and to 3.8 mmol/L (+/- 0.4 mmol/L) in the active LLLT group after exercise, but this difference between groups was not statistically significant.
CONCLUSION: We conclude that LLLT appears to delay the onset of muscle fatigue and exhaustion by a local mechanism in spite of increased blood lactate levels.
PMID: 18817474 [PubMed - indexed for MEDLINE]
BACKGROUND AND OBJECTIVE: The effect of photobiomodulation on delayed onset muscle soreness remains unknown. This study represents the first investigation of this treatment using an animal model.
METHODS: Seventy-two Sprague-Dawley rats were randomly divided into five groups: sedentary control group, exercise control group and three exercise-plus-laser groups. Downhill running was used to induce muscle injury in the gastrocnemius muscle. He-Ne laser irradiations were administered to the injured muscles immediately and at 18 and 42 h after exercise in the three exercise-plus-laser groups at 12, 28, and 43 J/cm2, respectively. Histological examination and serum creatine kinase (CK), muscle superoxide dismutase (SOD) and malondialdehyde (MDA) analyses were done at 24 and 48 h after exercise.
RESULTS: The exercise control group exhibited a marked inflammation in the gastrocnemius muscle and significant elevations in serum CK activity and muscle MDA level after downhill running. He-Ne laser irradiation at 43 J/cm2 inhibited muscle inflammation, significantly enhanced muscle SOD activity and significantly reduced serum CK activity and muscle MDA level at both 24 and 48 h after exercise, whereas the irradiation at 12 or 28 J/cm2 slightly inhibited muscle inflammation and significantly reduced serum CK activity at 48 h after exercise only (P < 0.05).
CONCLUSIONS: Low-level He-Ne laser therapy could exert therapeutic effects on eccentric exercise-induced rat muscle injury through enhancing muscle anti-oxidative capacity and reducing the inflammatory reaction. The photobiomodulation was dose-dependent, and the 43 J/cm2 dose was the most efficient among the doses used.
PMID: 19697999 [PubMed - in process]