Participation in sports promotes a physically active lifestyle, but carries an inherent risk associated with the nature of the sport and the physical demands placed on competitors. Athletes from all levels of participation, from student, collegiate and professional to recreational, often suffer from injuries, and rapid recovery is desired for a speedy return to competition.
Laser therapy was first introduced in the early 1980s as a means to resolve musculoskeletal pain. Since the first clinical trial was published investigating the effects of low-level laser therapy (LLLT) on rheumatoid arthritis,1 the positive effects of LLLT have been identified in other pathologies as well, including osteoarthritis,2 tendinopathies,3-4 wounds,5-6 back pain7 and neck pain.8-9
Low-level laser therapy has only been used in the United States since 2002, primarily in clinic settings. However, novel research continues to uncover other benefits and applications that chiropractic sports specialists in particular will find of interest. Going beyond accelerating injury rehab, LLLT has been shown to be particularly useful in the world of recreational and competitive sports by optimizing performance and training. This new research shows that laser may protect muscles from physical and chemical damage, improving athletes' field performance and recovery time following vigorous training and conditioning.
While Albert Einstein first proposed the term LASER (Light Amplification by Stimulated Emission of Radiation) in 1905, the first laser was not developed until the 1960s, giving rise to a new form of therapy called low-level laser therapy or LLLT. As defined by the North American Association for Light Therapy (NAALT), LLLT is any modality that utilizes photons of light (usually red and/or infrared) for tissue healing and pain reduction.10
It has been hypothesized that photonic energy absorbed by the cellular mitochondria fuels many physiological responses, called photobiostimulation, resulting in the restoration of normal cell morphology and function. Photostimulation is the process whereby a chain of chemical reactions is triggered by exposure to light.
LLLT is typically applied trancutaneously through the skin with a low-power laser or light-emitting diode (LED). There are several unique properties of laser (monochromaticity, coherence and low divergence) that allow photons to reach deep tissues like muscles, tendons and others. The light is typically11 of narrow spectral width in the red or near-infrared (NIR) spectrum (600 nm - 1,000 nm), with power output in the range of 1 mW – 500 mW, a power density (irradiance) between 1 mW to 5 W/cm2. As a point of interest, the vast amount of all laser therapy research has been performed with low-level lasers with these parameters.
Uses Beyond Rehabilitation: Athletic Performance and Recovery
Despite the documented health benefits of increased physical activity (e.g., weight management, improved self-esteem, and increased strength, endurance, and flexibility),12 those who participate in athletics are at risk for sports-related injuries.13-14 Athletes from all levels of participation – student, collegiate, professional and recreational – will suffer from injuries or worse, overtraining.
Athletes engage in training programs designed to improve endurance, speed, strength, explosive power, mental focus, agility and core strength. Exercise is a stressor that produces catabolic effects on the body, consumes contractile proteins within muscles for energy and strains connective tissue. The body's reaction to this stimulus is to adapt and replete tissues at a higher level than that existing before exercising. The results of regular training exercise are increased muscular strength, endurance, bone density, and connective-tissue toughness.
Many injuries are the result of overtraining or fatigue. Some are more severe than others. It is theorized that fatigue can be a contributing factor in sports injuries because it is more difficult for the body to protect itself when fatigued.15
The genesis of many injures that occur later in an athlete's career are due to improper training early in their career. Adequate time and rest is necessary for recovery; however, athletes always desire a more rapid recovery to continue training and conditioning. Laser therapy is showing promising results in improving performance and demonstrating that recovery requires more than just rest and water intake to resolve the catabolic effects of training.
Skeletal muscle fatigue is a novel area of research in LLLT. In the past few years, a Brazilian research group has performed a series of animal experiments and clinical trials16-27 that suggest very positive results from LLLT in terms of improving exercise performance and exercise recovery. The following table is a summary of the main results in the clinical trials. It is important to highlight that all studies were published in peer-reviewed scientific journals. [See reference list at end of article for complete citations.]
Table 1: Summary of clinical trials in LLLT and exercise performance and recovery performed by our research group.
|Authors||Source of light||Wavelength
|Energy density per diode
|Energy per site
|Power density per diode (W/cm2)||Treatment time per point or site
|Leal Junior, et al. 2008||Laser||655||500||5||5||100|
|Leal Junior, et al. 2009a||Laser||830||1,785||5||35.7||50|
|Leal Junior, et al .2009b||Laser||830||1,428 or 1,071||4 or 3||35.7||40 or 30|
|Leal Junior, et al. 2009c||Laser / LED||810 / 660 and 850||164.85 / 1.5 and 4.5||6 / 41.7||5.50 / 0.05 and 0.15||30 / 30|
|Leal Junior, et al. 2009d||LED||660 and 850||1.5 and 4.5||41.7||0.05 and 0.15||30|
|Leal Junior, et al. 2010b||Laser||810||164.85||30||5.5||30|
|Leal Junior et al. 2011||LED||660 and 850||1.5 and 4.5||41.7||0.05 and 0.15||30|
|Almeida, et al. 2012||Laser||660 or 830||1,785||5||17.85||100|
|De Marchi, et al. 2012||Laser||810||164.85||30||5.5||30|
|Miranda et al. 2013||LED||660 and 850||1.5 and 4.5||41.7||0.05 and 0.15||30|
|Authors||Power output per diode (mW)||Total energy delivered
|Number of treated points or sites||Muscle treated||When LLLT was applied?||Results|
|Leal Junior, et al. 2008||50||20||4||Biceps brachii||Before exercise||LLLT increased number of repetitions compared to placebo|
|Leal Junior, et al. 2009a||100||20||4||Biceps brachii||Before exercise||LLLT increased number of repetitions compared to placebo|
|Leal Junior, et al .2009b||100||40 or 30||5 each leg = 10 in total||Rectus femoris||Before exercise||LLLT decreased CK activity and lactate levels after exercise compared to placebo|
|Leal Junior, et al. 2009c||200 / 10 and 30||12 / 83.4||2 sites per limb with a single diode laser or a multidiode LED cluster (69 LEDs -34 red and 35 infrared)||Rectus femoris||Before exercise||LLLT significantly decreased CK activity after exercise|
|Leal Junior, et al. 2009d||10 and 30||41.7||1 site with a LED cluster (69 LEDs – 34 red and 35 infrared)||Biceps brachii||Before exercise||LLLT increased number of repetitions and time until exhaustion, and decreased CK, CRP, and lactate levels compared to placebo|
|Leal Junior, et al. 2010b||200||60||2 sites with a multidiode cluster with 5 spots (6 J each spot)||Biceps brachii||Before exercise||LLLT increased number of repetitions and time until exhaustion, and decreased CK, CRP, and lactate levels compared to placebo|
|Leal Junior et al. 2011||10 and 30||417 (208.5 per lower limb)||5 sites each lower limb with a LED cluster (69 LEDs -34 red and 35 infrared)||Quadriceps
(2 sites), Hamstrings
(2 sites), Gastrocnemius (1 sites)
|After exercise||LLLT significantly decreased CK activity and lactate levels after exercise compared to cold water immersion therapy and placebo|
|Almeida, et al. 2012||50||20||4||Biceps brachii||Before exercise||LLLT increased average strength and peak strength compared to placebo|
|De Marchi, et al. 2012||200||720 (360 per lower limb)||12 sites each lower limb with a multidiode cluster with 5 spots (6 J each spot)||Quadriceps
(6 sites), Hamstrings
(4 sites), Gastrocnemius (2 sites)
|Before exercise||LLLT increased VO2 max and time until exhaustion, decreased CK and LDH activity, decreased oxidative stress and increased antioxidant activity compared to placebo|
|Miranda et al. 2013||10 and 30||125.1||3||Quadriceps||Before exercise||LLLT increased time until exhaustion compared to placebo|
Results from 10 clinical trials already published suggest that LLLT improves exercise performance and recovery. When LLLT is applied before exercise, it appears to help protect muscles against exercise-induced damage and inflammation. This means our results can be translated and used in several situations in which improvement in muscle performance is required.
Currently, we are working to establish the optimal dose and parameters of LLLT for the improvement of exercise performance and enhancement of exercise recovery. There may be additional benefits of combining LLLT with other modalities, such as cryotherapy, for instance. Our preliminary results suggest that LLLT has a dose-response pattern, and different doses must be applied for short-term or long-term improvement of exercise performance and enhancement of exercise recovery. Additionally, our data suggest that cryotherapy can decrease efficacy of LLLT regarding biochemical markers related to exercise recovery.
Laser therapy has been assisting athletes to recover from injuries for years, accelerating the healing process. Now, LLLT may have the added benefit of improving an athlete's sports performance by allowing athletes to prepare, perform and recover from the catabolic stressors of intense training and competition.
- Goldman JA, Chiapella J, Casey H, et al. Laser therapy of rheumatoid arthritis. Lasers Surg Med, 1980;1:93-101.
- Hegedus B, Viharos L, Gervain M, GÃ¡lfi M. The effect of low-level laser in knee osteoarthritis: a double-blind, randomized, placebo-controlled trial. Photomed Laser Surg, 2009;27:577-84.
- Bjordal JM, Lopes-Martins RA, Iversen VV. A randomised, placebo controlled trial of low level laser therapy for activated achilles tendinitis with microdialysis measurement of peritendinous prostaglandin E2 concentrations. Br J Sports Med, 2006;40:76-80.
- Stergioulas A, Stergioula M, Aarskog R, Lopes-Martins RA, Bjordal JM. Effects of low-level laser therapy and eccentric exercises in the treatment of recreational athletes with chronic achilles tendinopathy. Am J Sports Med, 2008;36:881-7.
- Ozcelik O, Cenk Haytac M, Kunin A, Seydaoglu G. Improved wound healing by low-level laser irradiation after gingivectomy operations: a controlled clinical pilot study. J Clin Periodontol, 2008;35:250-4.
- Schubert MM, Eduardo FP, Guthrie KA, et al. A phase III randomized double-blind placebo-controlled clinical trial to determine the efficacy of low level laser therapy for the prevention of oral mucositis in patients undergoing hematopoietic cell transplantation. Support Care Cancer, 2007;15:1145-54.
- Basford JR, Sheffield CG, Harmsen WS. Laser therapy: a randomized, controlled trial of the effects of low-intensity Nd:YAG laser irradiation on musculoskeletal back pain. Arch Phys Med Rehabil, 1999;80:647-52.
- Chow RT, Heller GZ, Barnsley L. The effect of 300 mW, 830 nm laser on chronic neck pain: a double-blind, randomized, placebo-controlled study. Pain, 2006;124:201-10.
- Gur A, Sarac AJ, Cevik R, Altindag O, Sarac S. Efficacy of 904 nm gallium arsenide low level laser therapy in the management of chronic myofascial pain in the neck: a double-blind and randomize-controlled trial. Lasers Surg Med, 2004;35:229-35.
- North American Association of Laser Therapy (NAALT) Standards, 2003.
- Huang YY, Chen AC, Carrol JD, Hamblim MR. Biphasic dose response in low level light therapy. Dose Response, 2009;7:358-83.
- Move for Health: Benefits of Physical Activity. World Health Organization; 2006.
- Gotsch K, Annest JL, Holmgreen P, Gilchrist J. Nonfatal sports- and recreation-related injuries treated in emergency departments - United States, July 2000--June 2001. MMWR, 2002;51:736-40.
- Conn JM, Annest JL, Gilchrist J. Sports and recreation-related injury episodes in the U.S. population, 1997--1999. Inj Prev, 2003;9:117-23.
- Hoffman M. "How to Prevent and Treat the Seven Most Common Sports Injuries." Men.WebMD.com, Nov. 17, 2010.
- Almeida P, Lopes-Martins RA, Tomazoni SS, et al. Low-level laser therapy improves skeletal muscle performance, decreases skeletal muscle damage and modulates mRNA expression of COX-1 and COX-2 in a dose-dependent manner. Photochem Photobiol, 2011;87:1159-63.
- Almeida P, Lopes-Martins RA, De Marchi T, et al. Red (660 nm) and infrared (830 nm) low-level laser therapy in skeletal muscle fatigue in humans: what is better? Lasers Med Sci, 2012;27:453-8.
- De Marchi T, Leal Junior EC, Bortoli C, et al. Low-level laser therapy (LLLT) in human progressive-intensity running: effects on exercise performance, skeletal muscle status, and oxidative stress. Lasers Med Sci, 2012;27:231-236.
- Leal Junior EC, Lopes-Martins RA, Dalan F, et al. Effect of 655-nm low-level laser therapy on exercise-induced skeletal muscle fatigue in humans. Photomed Laser Surg, 2008;26:419-24.
- Leal Junior EC, Lopes-Martins RA, Vanin AA, et al. Effect of 830 nm low-level laser therapy in exercise-induced skeletal muscle fatigue in humans. Lasers Med Sci, 2009a;24:425-31.
- Leal Junior EC, Lopes-Martins RA, Baroni BM, et al. Effect of 830 nm low-level laser therapy applied before high-intensity exercises on skeletal muscle recovery in athletes. Lasers Med Sci, 2009b;24:857-63.
- Leal Junior EC, Lopes-Martins RA, Baroni BM, et al. Comparison between single-diode low-level laser therapy (LLLT) and LED multi-diode (cluster) therapy (LEDT) applications before high-intensity exercise. Photomed Laser Surg, 2009c;27:617-23.
- Leal Junior EC, Lopes-Martins RA, Rossi RP, et al. Effect of cluster multi-diode light emitting diode therapy (LEDT) on exercise-induced skeletal muscle fatigue and skeletal muscle recovery in humans. Lasers Surg Med, 2009d;41:572-7.
- Leal Junior EC, Lopes-Martins RA, de Almeida P, Ramos L, Iversen VV, Bjordal JM. Effect of low-level laser therapy (GaAs 904 nm) in skeletal muscle fatigue and biochemical markers of muscle damage in rats. Eur J Appl Physiol, 2010a;108:1083-8.
- Leal Junior EC, Lopes-Martins RA, Frigo L, et al. Effects of low-level laser therapy (LLLT) in the development of exercise-induced skeletal muscle fatigue and changes in biochemical markers related to post-exercise recovery. J Orthop Sports Phys Ther, 2010b;40:524-32.
- Leal Junior EC, de Godoi V, Mancalossi JL, et al. Comparison between cold water immersion therapy (CWIT) and light emitting diode therapy (LEDT) in short-term skeletal muscle recovery after high-intensity exercise in athletes--preliminary results. Lasers Med Sci, 2011;26:493-501.
- Miranda EF, Leal Junior EC, Marchetti PH, Dal Corso S. 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. Lasers Med Sci, 2013 [Epub ahead of print].
Douglas Johnson is a certified athletic trainer with a bachelor's degree in sports medicine from the University of Detroit-Mercy; and the senior vice president of clinical and scientific affairs for Multi Radiance Medical. He is involved in numerous research studies involving super-pulsed lasers, including investigating the impact of laser on knee pain; and is currently at work updating his text, Phototherapy 101, to Laser Therapy 101, which is scheduled to be released in late 2013.
Dr. Ernesto Leal-Junior, a full professor at Nove de Julho University in Sao Paulo, Brazil, is a peer reviewer for six different journals including Lasers in Medical Science, theJournal of Sports Sciences, the Journal of Photochemistry, and Photochemistry and Photobiology. He has lectured at Unilsalle University and the University of Caxias do Sul, both in Brazil, and has presented more than 40 scientific papers at national and international congresses. His expert area of research is phototherapy in skeletal muscle disorders, with a special interest in phototherapy for skeletal muscle fatigue delaying, performance enhancement, injury prevention and recovery after strenuous physical activity. In September 2011, Dr. Leal Junior was awarded the Young Clinical Research Award in Phototherapy by the North American Association of Laser Therapy.