Yoga Theory

Yoga techniques use gravity, leverage, and tension while holding poses for varying lengths of time. Ancient texts describe rapid breathing (kapalabhati) as cleansing and stimulating and slow breathing (nadisuddhi), particularly through alternate nostrils, as calming.

Yoga has undergone much scientific study, with various psychological and physical theories suggested. In human research, yoga has been shown to reduce heart rate and blood pressure, increase breath holding time and lung capacity, improve muscle relaxation and body composition, cause weight loss, and increase overall physical endurance. Yoga may positively affect levels of brain or blood chemicals, such as monoamines, melatonin, stress hormones (cortisol), and GABA (gamma aminobutyric acid). Changes in several mental functions, including perception, attention, cognition, processing of sensory information, and visual perception, are described in human research.

It is proposed that health may be affected by mind-body interactions that occur through techniques such as yoga, and that daily practice of yoga may help to maintain wellness.

Safety:

Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Yoga is generally considered to be safe in healthy individuals when practiced appropriately, and it has been well tolerated in studies with few side effects. Yoga can be adapted for a wide variety of specific needs, including for people who are bed-ridden or wheelchair-bound. Yoga techniques are believed to be safe during pregnancy and breastfeeding when practiced under the guidance of expert instruction (the popular Lamaze techniques are based on yogic breathing). However, poses that put pressure on the uterus, such as abdominal twists, should be avoided in pregnancy.

Some positions and postures should not be used by people with certain conditions or illnesses. Therapy should be exercised under well-qualified guidance. Patients with disc disease of the spine, fragile or atherosclerotic neck arteries, risk for blood clots, extremely high or low blood pressure, glaucoma, detachment of the retina, ear problems, severe osteoporosis, or cervical spondylitis should avoid some inverted poses. Certain yoga breathing techniques should be avoided in people with heart or lung disease. Some experts advise caution in people with a history of psychotic disorders (such as schizophrenia), due to a risk of worsening symptoms, although this has not been clearly shown in studies. People with medical conditions should speak with a qualified healthcare professional before starting yoga.

Rare side effects are described in case reports, including physical damage (due to prolonged postures), nerve or vertebral disc damage (due to prolonged postures, sometimes involving the legs), eye damage and blurred vision including worsening of glaucoma (due to increased eye pressure with headstands), and stroke/blood vessel blockage (due to decreased blood flow to the brain or other body parts from postures). Lung and breathing problems have been reported possibly resulting in death.

Yoga should not be used as a substitute for standard care, especially for potentially dangerous ailments such as asthma. Patients should seek the guidance of a qualified healthcare provider before embarking on any regimen of treatment.