Yoga, derived from the Sanskrit word for "union," is a disciplined practice. This mind-body therapy commonly refers to the use of physical postures, breathing exercises, and meditation to improve overall well-being (Quigley and Dean 2000). Developed several thousand years ago as part of traditional Indian medicine, or Ayurveda, yoga has become increasingly popular worldwide and is now practiced by a large number of Americans.

Yoga began in India nearly six thousand years ago. The earliest written records documenting yoga as a health practice are recorded in The Vedas, Indian texts dating back at least three thousand years. The physical, emotional, and spiritual benefits of yoga are also described in other ancient texts, including The Upanishads, The Bhagavad Gita, and The Yoga Sutras, the latter being considered the most complete document of yogic philosophy and teachings. However, yoga did not emerge as a fully developed practice until 500 B.C. In its traditional form, yoga is considered a complete lifestyle that provides a path to spiritual enlightenment (Quigley and Dean 2000).

The practice of yoga came to the United States in the 1890s as a result of the teachings of a guru named Swami Vivekananda. It gained popularity in the 1960s as a result of increasing cultural acceptance of alternative modalities and mind-body therapies. Today, yoga is often practiced as an exercise form divorced from its traditional spiritual underpinnings. In this form, yoga exercise is taught at local YMCAs, health clubs, and yoga centers, and is often part of disease prevention and management programs in hospitals, such as stress-reduction courses for patients with hypertension and coronary heart disease (Quigley and Dean 2000).

Yoga is based on the idea that the flow of prana, or life energy, in the body can be controlled and directed to induce healing and spiritual attunement (Quigley and Dean 2000).

There are many schools of yoga, each emphasizing varying degrees of the eight components of yogic practice: yama (restraint), niyama (observances), asana (postures), pranayama (breath control), pratyahara (withdrawal of the senses), dharana (concentration), dhyana (meditation), and samadhi (supreme consciousness) (Quigley and Dean 2000).

• Raja Yoga is called "the royal road to integration" and focuses on meditation (Quigley and Dean 2000).
• Hatha Yoga is the most common type of yoga practiced in the United States and focuses on yoga poses (asanas) followed by "counterposes" to balance and integrate the body (Quigley and Dean 2000).
• Jnana Yoga emphasizes the attainment of wisdom and oneness with God through deep contemplation and meditation (Quigley and Dean 2000).
• Karma Yoga is based on performing right actions or selfless acts of kindness, with no expectation of reward (Quigley and Dean 2000).
• Bhakti Yoga is the practice of devotion to God (Quigley and Dean 2000).
• Astanga, or Power Yoga, is a modern-day variation developed for people who prefer a physically demanding workout (Quigley and Dean 2000).
• Bikram Yoga is a series of 26 asanas practiced in 105-degree temperatures in order to warm and stretch the muscles, ligaments, and tendons, and detoxify the body through sweat (Quigley and Dean 2000).
• Iyengar Yoga was developed by B.K.S. Iyengar, a world-famous yoga teacher. This practice emphasizes great attention to detail, precise alignment, and the use of props, such as blocks and belts, to facilitate the postures (Quigley and Dean 2000).

Yoga, with its emphasis on the "union" of the total person, is considered a form of mind-body medicine, an approach to healing that integrates and harnesses the power of the physical, emotional, and spiritual aspects of a patient in order to enhance health and treat illness. Physical postures, known as asanas, provide a gentle workout that improves muscle strength, flexibility, body alignment, and enhances circulation as well as hormone function. Some postures are also thought to stimulate intestinal function, which may improve digestion and relieve constipation. In addition, the relaxation induced by yoga may help stabilize the autonomic nervous system. Although the exact mechanism is not understood, yoga is purported to tone the internal organs, including heart, lungs, glands, and nerves (Quigley and Dean 2000).

Yoga is also alleged to promote youthfulness and longevity. Breath control, called pranayama, reduces oxygen consumption and blood lactate, indicating better oxygen delivery and/or more efficient use (Quigley and Dean 2000). Yoga may also improve cardiorespiratory efficiency via decreases in heart rate, minute ventilation, and respiratory quotient (Raju et al. 1997). As is presumed the case with other mind-body therapies, yogic meditation elevates mood in association with hormonal changes in the hypothalamic-pituitary-adrenal (HPA) axis (Harte et al. 1995). Yoga also reduces blood pressure (Anand 1999) and seems to decrease serum cholesterol, triglycerides, LDL, and the cholesterol-HDL ratio (Mahajan et al. 1999). Furthermore, it stills the mind and induces physical and emotional relaxation (Quigley and Dean 2000).

Most people learn yoga by taking a group class with an experienced practitioner. Classes usually last from 45 to 90 minutes and begin with warm-up exercises, proceed to a guided series of yoga postures designed to stretch and tone all areas of the body, and end with deep relaxation and/or meditation. Throughout the class, the teacher instructs the students on breath control exercises and proper body alignment.

One of the major applications for yoga may be in the management of back pain (Quigley and Dean 2000). Studies also show that yoga has immediate and long-term benefits in decreasing anxiety and irritability, and improving self-confidence, concentration, mental efficiency, attentiveness, optimism, and relaxation (Malathi and Damodaran 1999). An analysis of randomized controlled trials suggests that yoga may help manage coronary disease by helping to decrease high blood pressure (Anand 1999), lower lipid levels in the blood (Mahajan et al. 1999), and increase resistance to stress (Pandya et al. 1999). Similarly, yoga exercises, breathing techniques, and meditation have been reported to be markedly effective in reducing the frequency and severity of angina when combined with dietary modification and stress-management training (the Ornish program) (Quigley and Dean 2000). One study demonstrates that yoga may be a valuable adjunctive therapy for asthma as it decreases the use of beta-adrenergic inhalers in asthmatic subjects (Vedanthan et al. 1998).

Clinical trials for the treatment of carpal tunnel syndrome indicate that yoga postures aimed at stretching and strengthening the joints in the upper body can improve grip strength and Phalen sign as well as diminish pain. The researchers concluded that yoga is more helpful than wrist splints in relieving some symptoms and signs (Garfinkel et al. 1998).

A randomized, controlled study on osteoarthritis suggests that yoga, as a mild form of exercise, may be effective for managing pain, improving motor control, and enhancing range of motion (Luskin et al. 2000; Garfinkel et al. 1994). Since arthritis affects nearly fifty percent of the elderly population and is the most prevalent chronic disease in the country, mind-body therapies such as yoga may become valuable alternatives to pharmaceutically based treatment (Luskin et al. 2000).

As with any physical activity, yoga can cause injury if practiced improperly. To prevent injury, yoga should be practiced under the guidance of an experienced teacher (Quigley and Dean 2000).

There are no known contraindications to yoga, but pregnant women and those with chronic disease or back pain should seek the guidance of an experienced yoga practitioner. People with chronic diseases such as arthritis, hypertension, or cardiovascular disease should consult with their healthcare professional before beginning a yoga practice, as they would before beginning any exercise program. Such patients should be sure to choose a slower and gentler style of yoga (Quigley and Dean 2000).

In addition to conditions already discussed, yoga may be beneficial for adjunctive treatment of many conditions including addictions; chronic fatigue syndrome; weight management; eye disorders such as conjunctivitis and macular degeneration; hearing disorders; gastrointestinal disorders such as gastritis, constipation, diverticulosis, diverticulitis, Crohn's disease, colitis, irritable bowel syndrome, and hemorrhoids; diabetes; respiratory disorders in addition to asthma such as emphysema, bronchitis, obstructive sleep apnea, and even lung cancer; allergic rhinitis or sinusitis; headaches; hyperactivity; impotence; insomnia; postpartum care; menopause; menstrual problems such as cramps, premenstrual syndrome, and amenorrhea; endometriosis; multiple sclerosis; rheumatoid arthritis; osteoporosis; gout; and restless leg syndrome (Quigley and Dean 2000).

Given the impact of stress on both physical and mental health, yoga is an important consideration for both health maintenance and adjunctive treatment of many conditions (Apte and Kabekar 1998; La Forge 1997). Increasing focus on disease prevention and long-term behavior change for the management of chronic disease supports the use of yoga as part of a self-care regimen for both therapy and prevention of conditions such as cardiovascular disease (La Forge 1997).

Each yoga style or school offers teacher training and certification programs, which include in-depth study of yoga asanas, breathing exercises, meditation, mantras, anatomy and physiology, yogic history and philosophy, and yogic diet. Currently, a number of practitioners from various schools are developing a national standardized teacher certification (Quigley and Dean 2000).

For general information on yoga, referral information, and a list of books, audiotapes, and videotapes, contact the American Yoga Association in Sarasota, Florida at 941-927-4977 or on the web at www.americanyogaassociation.org. The Yoga Research and Education Center (YREC) in Sebastopol, California publishes the International Journal of Yoga Therapy; for a subscription, call 707-928-9898 or consult the web site at www.yrec.org. The YREC web site also provides access to its clearinghouse on medical, psychological, and scientific research on yoga, as well as general, referral, and training information. Yoga Journal is a highly respected publication that follows the current trends in yoga; subscriptions can be ordered by calling 800-600-9642. In addition, the Yoga Journal web site at www.yogajournal.com lists conferences, offers books and videos, and maintains both print and online directories of yoga teachers and training programs.

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