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By Russell H. Greenfield, MD, FACEP
Currently, an estimated 15 million Americans have asthma, and more than half were diagnosed with the disease before age 17.1 In 1990, costs associated with asthma care alone were estimated to be $6.2 billion, or 1% of all U.S. health care costs that year.2 In spite of the significant therapeutic advances witnessed in recent years, morbidity and mortality rates in industrialized nations have actually been increasing.3
Asthma is a chronic inflammatory disorder of the tracheobronchial tree. Its clinical appearance as airway obstruction occurs through a number of pathophysiologic processes. Some experts believe that exaggerated activity of the parasympathetic nervous system may have a negative influence on airway caliber and resistance. Emotional stress, in addition to other commonly noted physiologic triggers, is a recognized precipitant of asthma exacerbation.
Yoga, the Indian discipline said to enhance physical, mental, and spiritual health, has long been promoted in Europe and Asia as a useful adjunct in the treatment of asthma. With the practice of yoga gaining popularity in the United States, and with additional research examining its effects and use, more asthmatic patients are exploring its potential therapeutic benefits.
The discipline of yoga is thousands of years old and is an essential part of the practice of Ayurveda, one of the oldest complete medical systems in the world. Many ancient texts mention yoga, including the Rig-Veda (written approximately 4000 years ago), the Upanishads (scriptures of ancient Hindu philosophy), and the Bhagavad Gita (perhaps the most famous Hindu text).
Yoga was introduced to America at the 1893 Chicago World’s Fair.4 The word yoga is derived from a Sanskrit root meaning to yoke or unite, and the practice of yoga traditionally has been held to unite body, mind, and spirit in an attempt to enhance health and quality of life.
A common misconception is that yoga is a religious practice. Instead, yoga is a discipline of conscious living that encourages, but does not mandate, spiritual reflection. Yoga helps those who practice it to improve overall fitness and well-being. It can complement any religious or spiritual practice, or yoga can be practiced completely apart from one.
There are many different forms of yoga and many ways to practice the art, but perhaps the most common components of the discipline as taught in the United States are postures (asanas), breathing practices, and meditation.
The postures are designed to increase flexibility and to induce both physical and mental relaxation. There are literally thousands of asanas, but most people use only a few in their personal practice.
During the performance of these postures, great effort is made to concentrate on the breath. Breathing exercises (called pranayama) are performed both in association with asana practice and by themselves. The breathing exercises are seen as vital to the maintenance of health, and while most are intended to be deep and diaphragmatic, they need not be demanding. Breathing techniques are viewed as the foundation for meditative work.
Typical yoga sessions last for one hour and end with five to 20 minutes of meditation.
Yoga practice has traditionally been viewed as appropriate for anyone regardless of age or ability. The object of yoga practice is not competition but to take the body from a place of discomfort to one of comfort by relaxing and strengthening it. Participants are instructed to practice slowly and carefully and not to force their bodies or invite discomfort.
Yoga therapy has not been considered disease-specific in that distinct practices generally have not been taught only to patients with a particular malady. More prescriptive forms of yoga have become available only recently.
Yoga’s potentially therapeutic mechanisms have not been determined precisely. One of the most common explanations, not specific to asthma, is stress reduction with concomitant physical and psychological relaxation.
Physiologic changes associated with deep relaxation include diminished muscle tension, which allows for more efficient use of the diaphragm and thoracic musculature. Decreased oxygen use is also generally noted with various stress reduction techniques. These changes are consistent with an overall calming of autonomic tone,5 which may manifest as a decrease in vagal efferent activity. The result is enhanced bronchodilation and diminished bronchial reactivity.
Another explanation, more specific to asthma, suggests that yoga practice may improve the mechanical aspects of breathing. The postures and breathing exercises used improve flexibility, massage the thoracic musculature, encourage increased tidal volume and decreased respiratory rate, and decrease bronchial reactivity. The end result is an increase in the efficiency of chest wall movement during the respiratory cycle.
Enhanced adrenocortical activity6 has been reported in association with the practice of yoga, although the degree of enhancement has not been quantified. It is postulated that symptoms improve as a consequence of this increased activity and the resultant decrease in bronchial inflammation and hyperreactivity, as well as a blunted physiologic response to stress.
The majority of reports suffer from serious methodologic flaws. Many of the studies provide data on only a small number of patients, are uncontrolled, include confounding factors, and use various "cleansing procedures." Publication bias is also evident, as a thorough literature search failed to identify a single study in which yoga did not produce improvement or had a negative effect.
Several studies, however, are worth examining. One randomized, controlled study followed 106 asthmatic patients for a six-week period.7 The 53 patients in the treatment group received training in postures, breath-slowing techniques, and meditation. Then, they were instructed to practice for approximately one hour each day.
At randomization, the control group was felt to be equally as inclined toward the practice of yoga as the treatment group. At the end of the study period, the treatment group experienced a significant decrease in the number of weekly asthma exacerbations, an increase in peak expiratory flow rate (PEFR), and a decrease in the amount of medication used.
The same authors also reported a parallel study of 570 patients who trained in and practiced yoga, and who were followed for periods ranging from three to 54 months.8 They noted an improvement in PEFR and a significant decrease in the need for medication. Those who practiced regularly had the greatest improvement.
Khanam et al, in a pre-/post-period analysis trial, were able to show benefit for asthmatic patients after only one week of intensive training in postures, breathing techniques, and the underlying philosophy of yoga.9 Subjects served as their own controls, ate a strictly vegetarian diet, and were maintained in an environment described only as one of "maximum relaxation."
At the end of the trial there was no significant difference in forced expiratory volume in one second (FEV1) or PEFR, but significant improvement was noted for peak inspiratory flow rate, breath holding time, and the degree of chest expansion. Resting heart rate decreased (P < 0.05), and patients reported an improved sense of overall well-being.
Another study used a randomized, double-blind, placebo-controlled, crossover design to evaluate the effects of pranayama breathing exercises on 18 patients with mild asthma (mean FEV1 = 3.2 L).10
All subjects initially practiced 15 minutes of slow, deep-breathing exercises twice a day for two weeks. During the active phase of the study, patients in the treatment arm used a device that imposes a 1:2 inspiration to expiration ratio equivalent to a form of pranayama breathing. The control group was provided a placebo device of similar appearance. At the end of the four-week trial, there was a significant decrease in bronchial reactivity, on the order of one doubling dose of histamine, in the group practicing pranayama. No other significant differences were found.
Singh previously noted a beneficial effect in a small, six-week study using the same device for patients with mild asthma and nocturnal wheezing.11 Patients in this randomized, crossover trial used the device alone and in combination with warmed, humidified air. A beneficial effect on nocturnal wheezing and PEFR was noted at the end of the study. There was a slight trend toward improved results with combination therapy.
The practice of yoga is safe provided patients do not push themselves beyond their limits of comfort.
The patient should be instructed to go the point of minimum tension and not to the point of stress. A sense of competition often leads to straining to maintain a pose and subsequent physical injury.
However, there are rare reports of disability related to the practice of yoga, including vertebral artery dissection,12-15 persistent out-of-body experiences,16 and the development of orbital varices.17 Patients with known cerebrovascular insufficiency should be cautioned against prolonged head turning during yoga practice.
Yoga requires commitment, both with respect to time and practice. The beginning student may choose to observe a class and the instructor before deciding whether to experience yoga.
No national standard for teacher certification exists, unfortunately, and credentials vary greatly. It is prudent to recommend that patients find a highly regarded instructor with at least four years of teaching experience.
Prior to entering an open class, they should consider reserving a private session, which may cost from $25 to $45. During this pre-program evaluation, patients can advise the yoga teacher of any medical problems or injuries that might limit their ability to participate in the various aspects of the discipline. This will allow the instructor to tailor a comfortable practice that does not compel the patient to compete with those more flexible or in better health.
Individual hour-long group classes cost approximately $6 to $8 each, but discounts are usually available when several classes are purchased. Ideally, one should develop a yoga practice that becomes a part of a regular daily routine.
Yoga is safe, affordable, and potentially beneficial to the asthmatic patient’s health and sense of well-being. Whether that benefit is due to a direct effect on bronchodilation and inflammation or to a reduction in stress has yet to be determined. Yoga provides a sense of control and involvement in disease treatment that medications alone cannot offer. In the end, this may be the single most important reason to consider including yoga in the treatment plan for asthmatic patients.
While the scientific data to support the use of yoga is suggestive at best, there does appear to be support for consideration of its use as an adjunct for most stable patients with mild to moderate asthma.
Our clinic experience also suggests that asthmatic patients who are motivated to decrease the use of medications, who believe that stress plays a significant role in their disease process, and whose expectations support a positive response tend to have the greatest improvement in function and quality of life with a regular yoga practice.
Russell H. Greenfield, MD, is a Fellow in the Program in Integrative Medicine at the University of Arizona in Tucson.
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