The Therapeutic Application of Yoga: a Literature Review
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The Therapeutic Application of Yoga: A Literature Review By: Ashley Richiardi Faculty Advisor: Rodger Tepe, PhD A senior research project submitted in partial requirement for the degree Doctor of Chiropractic March 28th, 2013 ABSTRACT Objective This review provides an overview of the current literature discussing the health benefits and therapeutic applications of yoga in the treatment and management of a variety of mental and physical conditions. It seeks to qualify the research that exists to support or refute the use of yoga either as a stand-alone therapy or in conjunction with traditional treatments. Data Collection A computer search of PubMed, Google Scholar, and The Cochrane Collaboration literature databases was performed using the following terms: yoga, therapeutic, therapy, application, benefits, flexibility, strength, balance, low back pain, anxiety, depression, arthritis, pregnancy, asthma. Articles included in this review met the following criteria: (1) peer-reviewed (2) published between 2000-2013 (3) discuss the use of yoga as an intervention. Conclusion Sufficient research exists to substantiate claims that yoga increases flexibility, strengthens muscles, and improves balance and respiration. Current research demonstrates that yoga is a beneficial therapy for low back pain, osteoarthritis, asthma, anxiety, and depression. Additional research into the application of yoga in pregnancy and rheumatoid arthritis is warranted. Key Indexing Terms Yoga, Therapeutic, Application, Benefits Richiardi - Therapeutic Application of Yoga P a g e | 2 INTRODUCTION Yoga is an ancient mind-body therapy believed to have originated in India around 3000 BC. It was not until the end of the 19th century that yoga’s popularity reached the United States. Yoga has quickly become a mainstream exercise and relaxation practice in Western society. Around the 20th century the observed psychophysiological benefits spurred the advancement in the study of the therapeutic application of yoga. Yoga is now classified as a form of Complementary and Alternative Medicine (CAM) by the National Institutes of Health and has a considerable body of evidence to support its use in a variety of conditions. A 2012 study conducted by The Yoga Journal found that an estimated 20.4 million Americans practice yoga, spending $10.3 million a year on yoga services and merchandise.1 Additionally, 44% of currently non-practicing Americans report interest in beginning their own yoga practice.1 Due to the increased public interest in this health practice it is crucial to rigorously review the current research to determine the role yoga can serve in the management and treatment of specific conditions and populations. While many forms of yoga exist, Hatha yoga is the most widely practiced type of yoga in the world. In this form of yoga various postures (asanas) are incorporated with deep breathing techniques (pranayamas) and meditative practices (dhyanas). Yoga literally means “to join,” in reference to uniting the mind, body, and breath in one restorative practice.2 Originally Hatha yoga emphasized the mental and spiritual benefits of the practice, but since its adoption in Western culture the physical benefits have become the focus. The following yoga-related health claims will be evaluated in this review: increases flexibility, increases muscle strength, improves balance, and improves breathing patterns and Richiardi - Therapeutic Application of Yoga P a g e | 3 lung function. Additionally, yoga has been suggested to be beneficial for a range of conditions, and the following will be included in this article: musculoskeletal disorders such as low back pain and osteoarthritis, pregnancy-related pain syndromes and disorders, asthma, and mental disorders including anxiety and depression. This research review explores both the physical and mental health benefits, therapeutic applications, and the proposed mechanisms of how yoga may improve health. DISCUSSION Health Benefits It is important to first address the impact that a regular yoga practice can have on overall health prior to discussing its application to specific conditions and populations. The most common health claims tied to yoga include increased flexibility, stronger muscles, improved balance, and improved breathing patterns and lung function. Increases Flexibility Flexibility is commonly associated with advanced yogis, and is also reported as the number one reason people begin a yoga practice.1 The asana component of yoga moves the body in and through poses which stretch specific muscles, tendons, fascia, and connective tissues.3 As soft tissue tension diminishes joints tend to exhibit an enhanced range of motion, as seen in advanced yoga poses. A 2012 study of 250 subjects with osteoarthritis of the knee joint compared the range of knee flexion in patients performing 40 minutes daily of either hatha yoga (intervention) or therapeutic exercises (control) following transcutaneous electrical stimulation and ultrasound Richiardi - Therapeutic Application of Yoga P a g e | 4 therapy.4 Measurements were taken on the 15th and 90th day of a 90 day intervention. This study found that the yoga group had significantly greater knee flexion (12.7% at 15 days, 26.5% at 90 days on the right; 13.5%, 28% left) than the control group (6.9%, 13.3% right; 5.6%, 11.5% left) at the time of both measurements.4 A randomized controlled trial conducted in 2013 evaluated the efficacy of a 9 week Iyengar yoga intervention compared to a home exercise control group in the treatment of chronic neck pain.5 Baseline and post-intervention measurements of cervical range of flexion, extension, bilateral rotation, and bilateral lateral flexion were obtained. The yoga group demonstrated greater gains in all cervical ranges of motion compared to the home exercise group.5 Chen et. al. found a significant increase in shoulder and hip ranges of motion in an elderly population following yoga therapy.6 An exploratory study (n=21) of the effect of an 8 week Bikram yoga practice in healthy young adults found significant increases in lumbar spine, hamstring, and shoulder flexibility when compared to a control group.7 Increased flexibility is the most widely accepted health claim associated with a regular yoga practice. A considerable body of evidence exists to support this claim; however, further research in healthy populations with larger sample sizes is warranted. Increases Muscle Strength Muscle loss is a normal component of the aging process, but if uncontrolled it can lead to arthritis, back pain, and falls in the elderly.3 Several forms of weight-bearing exercise can promote increased muscle strength, but few activate the intrinsic musculature and lead to the overall muscle balance that yoga does. The Bikram study referenced earlier measured dead-lift strength and hand-grip strength in 21 healthy young adults pre- and post-intervention. The results demonstrated a significant Richiardi - Therapeutic Application of Yoga P a g e | 5 increase in dead-lift strength and no change in grip strength in the yoga group when compared with the control group.7 A larger study (n=143) looked at hand-grip strength in healthy adults, children, and patients with rheumatoid arthritis. This study found significant increases in hand- grip strength across all three populations receiving the yoga therapy compared to controls.8 The asanas used in Hatha yoga challenge various muscle groups and with continued practice can lead to measurable gains in muscle strength.7,8 Some types of yoga (i.e Vinyasa, Ashtanga) are more rigorous than others and require the body to flow through poses seamlessly with breath, and are presumed to have a greater impact on muscle strength. Forms of therapeutic yoga that do not utilize weight-bearing postures and focus on relaxation of muscles may not offer this same benefit. Improves Balance Proprioception is another common age-related physiological functional loss. Diminished balance is associated with an increased risk of falls, a leading cause of hip fractures, loss of independence, and death in the elderly population.9 For this reason it is critical to evaluate the efficacy and safety of therapies that may help improve proprioceptive functioning to enable clinicians to make appropriate recommendations. A Cochrane review of 94 randomized controlled studies (n=9,821) looked at the effect of various exercise programs on proprioception in an older population.9 Yoga was one intervention in a group referred to as “3-D exercise,” which also included tai chi, qi yong, and dance. This research review found a moderate improvement in balance immediately post-intervention for the 3-D exercise group.9 It is not possible to draw any conclusions on the relative efficacy of yoga versus similar therapies included in the 3D group based on the nature of this review. Several Richiardi - Therapeutic Application of Yoga P a g e | 6 studies looking specifically at yoga have found it to be a useful intervention for improving balance in older adults. Brown et. al. found a 9.7 ± 9.4s improvement in one leg balancing following a 4 week yoga intervention.10 Oken et. al. conducted a 6 month long randomized controlled trial comparing a hatha yoga group to a walking exercise group and a wait-list control group.11 Yoga was found to be superior to both the exercise and control group in improving balance measures in the elderly.11 Improves breathing patterns and lung function While many of the previous health benefits are likely a result of the asana component of yoga practice, improvements in respiratory function are largely attributed to the pranayamas, or breathing techniques of yoga. There are many aspects of pranayama that may contribute to enhanced lung function and improved breathing patterns. Nostril breathing is used for both inhalation and exhalation during yoga, allowing the nasal passages to act as a filter to warm and humidify the air while removing irritants before they reach the lungs.3 Slow, deep breaths are emphasized creating a calming effect on the nervous system.3 In Vinyasa (flow) yoga the goal is to seamlessly integrate the body movements with the breath, allowing a fluid transition from pose to pose.