Light therapy has been used for years to treat an array of medical conditions and diseases—from skin conditions like psoriasis to seasonal affective disorder and depression. [1,2]
But more recently, scientists have begun studying the effects of light waves—specifically red and near infrared (NIR) wavelengths—for the purposes of muscle recovery and athletic performance. These types of light frequencies penetrate the skin and trigger chemical and physiological actions deep inside the body. Medical researchers are now beginning to realize how important these mechanisms can be in promoting good health—and specifically for the repair of damaged tissues.
In fact, a large number of clinical studies have found that both red and NIR light can also help repair muscle tissue in athletes, build muscle more efficiently, enhance their training, and help them compete more effectively.[1-12]
But how does it work?
Light Therapy Fuels Your Muscle Tissues
We all know we need sunlight to stay healthy. Plenty of studies underscore the role of sunlight in the production of vitamin D—even as far back as the first century A.D., Roman scholar and naturalist Pliny the Elder extolled sunlight as “the greatest remedy.”
But despite the sun’s longtime reputation as a natural healer, it’s taken us thousands of years to figure out how the sun promotes healing responses in the body, particularly in the muscles. As noted in a previous article, it all starts deep in the cells where tiny structures called mitochondria take in nutrients, process them, and convert them to an energy source that the cells can use to function and repair themselves. Different types of cells have different energy requirements, so they contain different numbers of mitochondria.
Muscle tissue has high energy demands, and so mitochondria abound. In fact, it’s these high levels of mitochondria inside the muscle tissue that makes red and NIR light therapy so effective in promoting muscle health.
Red and NIR Light Prevent Muscle Fatigue
One of the primary ways light therapy helps promote better muscle health and function is by preventing or limiting muscle fatigue, especially strenuous exercise and training. A 2012 trial printed in Lasers in Medical Science, for example, found that red and NIR light therapy is effective in preventing muscle fatigue and enhancing skeletal muscle performance.  So how does light therapy actually provide these benefits?
At the most basic level, red and NIR light therapy improve the cellular respiration cycle, helping the mitochondria in cells produce energy more efficiently—and that means muscles are less likely to suffer from fatigue. Red and NIR light also help promote the production of antioxidants, which play a central role in reducing oxidative stress associated with muscle fatigue. And they also increase the production of heat proteins—special proteins that help protect cells from stress and early cell death (called apoptosis). [4,5] Plus, light therapy helps reduce inflammation that can lead to cell damage. [6,7,8]
Some studies have even shown an increase in circulation following light therapy, indicating tissues are receiving more oxygen and other nutrients important for healing—while also ridding themselves of toxic byproducts.
Light Therapy Enhances Muscle Growth
Muscle function and repair are important for improving strength and endurance, while reducing fatigue and soreness following workouts and physical activity. But the benefits of red and NIR light therapy don’t stop there. Research found in the American Journal of Physical Medicine and Rehabilitation shows that the application of light therapy also promotes the growth of healthy muscle tissue, or muscle hypertrophy, naturally increasing muscle size and bulk—as well as strength. [10,11]
In fact, a separate study printed in the European Journal of Applied Physiology compared muscle growth and strength between two groups of athletes—one using light therapy combined with exercise, the other using exercise alone—and found that muscle thickness and strength were significantly improved (by over 50%!) in those who used light therapy. These results were clearly measurable using ultrasound imaging and isokinetic dynamometry (Figure A). 
Figure A: Percent change (mean ± SE) in peak torque of isometric (PT ISO ) and eccentric (PT ECC ) tests in Control Group (CG), Training Group (TG) and Training + LLLT Group (TLG)
The Long-Term Benefits of Light Therapy
In addition to enhancing muscle repair, improving strength and size, and decreasing muscle fatigue, light therapy also offers long-term benefits for future muscle health and development by targeting muscle stem cells called myosatellite cells.
Like other types of stem cells, muscle stem cells remain in an undifferentiated state until activated, at which point they develop into specific types of muscle cells. Just as mitochondria produce the energy cells need for optimal function and repair, they also help regulate muscle stem cell activation and differentiation—essentially guiding stem cells into their final form as healthy muscle tissue. Since light therapy enhances mitochondrial action, it may also play an important role in stimulating the growth of new muscle cells and tissue used to “speed up” the repair process following muscle injury or fatigue—improving overall muscle health and function in the long run. 
Light Therapy: Perform Better and Recover Faster with Natural Energy
Red and NIR light therapy shows amazing promise as a drug-free way to enhance and improve muscle function, strength, and performance—as well as improving muscle size and bulk—to help athletes of all levels train and compete better. And the natural healing mechanisms stimulated by light therapy can help athletes heal more quickly following injury, while also preventing muscle fatigue and soreness that can interfere with both training and competitive performance.
Plus, light therapy can be performed in a professional setting or at home, making it extremely accessible. But as noted before, wavelength and intensity are the key factors when it comes to light therapy. Make sure you choose a device that delivers red or near infrared light with the correct wavelength along with an optimal amount of power.
For athletes of all backgrounds—from pros to students to “weekend warriors”—light therapy is a scientifically-backed approach that can have significant and long-lasting benefits.
Scientific Sources and Medical References:
 S. Tami Wong, B.A. Leon Hsu, M.D. Wilson Liao. Phototherapy in Psoriasis: A Review of Mechanisms of Action. J Cutan Med Surg. 2013. Jan-Feb;17(1):6–12.
 Terman, M. and Terman, J.S. (2005) ‘Light Therapy for Seasonal and Nonseasonal Depression: Efficacy, Protocol, Safety, and Side Effects.’ CNS Spectrums. 10(8), pp. 647–663.
 de Almeida P1, 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 Mar;27(2):453-8.
 Avni D, Levkovitz S, Maltz L, Oron U. Protection of skeletal muscles from ischemic injury: low-level laser therapy increases antioxidant activity. Photomed Laser Surg. 2005;23:273–277.
 Rizzi CF, Mauriz JL, Freitas Correa DS, et al. Effects of low-level laser therapy (LLLT) on the nuclear factor (NF)-kappaB signaling pathway in traumatized muscle. Lasers Surg Med. 2006;38:704–713.
 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.
 Aimbire F, Albertini R, Pacheco MT, et al. Low-level laser therapy induces dose-dependent reduction of TNF alpha levels in acute inflammation. Photomed Laser Surg. 2006;24:33–37.
 Hemvani N, Chitnis DS, George M, Chammania S. In vitro effect of nitrogen and He-Ne laser on the apoptosis of human polymorphonuclear cells from burn cases and healthy volunteers. Photomed Laser Surg. 2005;23:476–479.
 Tullberg M, Alstergren PJ, Ernberg MM. Effects of low-power laser exposure on masseter muscle pain and microcirculation. Pain. 2003;105:89–96.
 Halliwell B, Gutteridge JC. Free radicals in biology and medicine. Oxford: Oxford University Press; 2000.
 Ferraresi C, Bertucci D, Schiavinato J, et al. Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study with a Pair of Identical Twins. Am J Phys Med Rehabil. 2016 Oct;95(10):746-57.
 Baroni BM1, Rodrigues R, Freire BB, et al. Effect of low-level laser therapy on muscle adaptation to knee extensor eccentric training. Eur J Appl Physiol. 2015 Mar;115(3):639-47.
 Ferraresi C, Hamblin M, and Parizotto N. “Low-level laser (light) therapy (LLLT) on muscle tissue: performance, fatigue and repair benefited by the power of light.” Photonics Lasers Med. 2012 November 1; 1(4): 267–286. doi:10.1515/plm-2012-0032.