Treating Sports-related Injury and Pain with Light Therapy
Americans are more active in sports, at all ages, than ever in our history. Baby boomers, now in their 40’s and 50’s deny the inevitable aging of their bodies in order to keep a youthful intensity to their sports activities. Meanwhile American children are being pushed into high intensity training and new levels of competitiveness at younger ages than ever before. And in the middle, X-treme sports rule. All of these factors are resulting in escalating levels of sports related injuries and pain. New modalities to treat injury and pain are proliferating and now a few “old” modalities are gaining broad audiences in the U.S.
The Evolution of Sports Medicine1
Galen was a second century AD Greek physician who was one of the first to rigorously depict human anatomy. Working with gladiators in Rome, he gained first hand knowledge of anatomy and physiology through treating their wounds. As such, he might be considered the first “Sports Medicine Specialist.” He was also a keen observer who used the gladiatorial athletes to test treatment modalities. Galen was also a creature of his time, prescribing what today would be considered odd treatments and curatives, including purgatives, blistering agents, and that foundation of medical intervention for 2,000 years: bleeding. But the Romans also understood the value of a hot bath and massage to health. Other modalities have made their way through the centuries as well. Acupuncture has been practiced in China for over a thousand years. Societies around the world and throughout time have taken advantage of the medicinal properties of a variety of plants containing natural opiate substances.
Modern Western Medicine: Approach to Injury and Pain
In the middle and late 19th century, western medicine made great strides forward in pain management with the chemical determination and synthesis of opiates for anesthesia and pain control, and the isolation of salicylates from the bark of the willow tree to treat pain and inflammation. The powerful effectiveness of opiate treatments led western medicine to focus on pharmaceutical treatment of pain, almost to the exclusion of non-pharmaceutical approaches through much of the 20th century.
“New” Modalities for Treating Injury and Pain
However, drug therapy comes at a price. Non-steroidal anti-inflammatory drugs cause significant bleeding stomach ulcers in 2% of patients.2 Twenty percent of these die of the bleeding. Newer COX-2 selective inhibitors obviate most of this risk, but bring in additional risks for those with concomitant cardiovascular disease. This has resulted in the withdrawal of several popular COX-2s including Vioxx and Bextra. Opiates have long been recognized for their addictive side effects. According to the Drug Enforcement Administration, 6.2 million people abuse prescription drugs.3 Therefore, new approaches to injury and pain management have emerged in western medicine over the past twenty years. The side effects and potential addiction problems associated with pharmaceutical approaches have contributed to the search for complimentary and alternative medicine for pain.
Acupuncture, electrical stimulation, acupressure, relaxation, and biofeedback are all being explored as alternatives or adjuncts to drug therapy. Electrical stimulation and ultrasound have been used more recently for stimulation of fracture healing. Controlled studies measuring the effectiveness of these therapies have brought them into the mainstream of legitimate approaches to therapy.
A novel therapy introduced to western medicine over the past 15-20 years is photo-biostimulation, or light therapy. Phototherapy is the application of specific light wavelengths and energies to body tissues that elicits a complex chain of biochemical responses. Most of the focus is on red and near infrared wavelengths. Much of the early work was conducted in the former Soviet Union and its East European satellite countries. The impetus was to improve performance and injury recovery in both military and athletic patients.
The technology currently being used in the U.S. is largely in the form of lasers. More recently, a number of devices have emerged which use Light Emitting Diodes (LEDs). LEDs provide a safer and more affordable technology for delivering light therapy (also referred to as phototherapy). Physiotherapists and sports medicine specialists are treating a wide variety of acute and chronic musculoskeletal injuries and pain with phototherapy. The benefits of light therapy are that they reduce the discomfort of pain and inflammation while promoting blood flow and the body’s own tissue repair mechanisms.
Mechanisms of Action: IR and Tissue Healing
Infrared (IR) therapy stimulates the body’s natural healing mechanisms. Evidence suggests that this occurs at both the molecular signaling level and at a more macro level through circulatory modulation. One of the most important mechanisms of action for near infrared light therapy is the release of nitric oxide. A naturally occurring chemical in the body, nitric oxide (NO) is a key signaling molecule which can set off a number of beneficial effects. Most notably, it has a critical role in promoting blood flow to tissues and increasing lymphatic drainage. Through the increase in lymphatic drainage, IR indirectly inhibits inflammation processes and thus reduces swelling.
IR Stimulation of Signaling Pathways
Recent work has shed light on the underlying mechanisms of tissue repair within the body. Conboy et al,4 investigated the influence of systemic factors on aged progenitor cells (specifically, satellite cells) of peripheral tissues such as muscle and liver. Muscle satellite cells are quiescent precursors interposed between myofibrils and a sheath of external lamina. Their activation and recruitment enables muscle repair and adaptation. Conboy’s team conducted an experiment wherein they established parabiotic pairings (that is, a shared circulatory system) between young and old mice (heterochronic parabioses), exposing old mice to factors present in young serum. Notably, heterochronic parabiosis restored the activation of Notch signaling as well as the proliferation and regenerative capacity of aged satellite cells in muscle tissue. In vitro, the exposure of satellite cells from old mice to young serum enhanced the expression of the Notch ligand (Delta), increased Notch activation, and enhanced proliferation.
More insight into possible signaling mechanisms comes from work on nitric oxide in muscle tissue. Evidence points to nitric oxide as a mediator of satellite cell activation. Cell isolation and histology experiments showed that pharmacological inhibition of nitric oxide synthase (NOS) activity prevented the immediate injury-induced myogenic cell release and delayed the hypertrophy of satellite cells in muscle. NOS inhibition delayed and restricted the extent of repair and resulted in fiber branching (scarring).5