Yoga is an ancient Indian discipline that has been practiced in the East for over 5000 years. It is gaining extreme popularity in the United States. According to the National Health Interview Survey,6.1% of US adults practiced yoga in the months immediately prior to the survey in 2007, compared with 3.7% in 1997 and 5% in 2002. The figures for 2011 are expected to be much higher.
Yoga was first introduced to the West by Swami Vivekananda, who toured Europe and the United States in the 1890s. More recently, Dean Ornish, a follower of Swami Satchidananda, published several studies legitimizing yoga exercises and yogic lifestyle for its cardiovascular benefits.
The Yoga Sutras are foundational texts of Yoga and are attributed to Patanjali, dating back to the 2nd century BC. According to Patanjali, yoga has eight limbs. These are:
1. Yama which encompasses non-violence, honesty, non-coetousness, non-sensuality and non-possesiveness.
2. Niyama which reflects purity, contentment, austerity and surrender to God.
3. Asana which refers to the seated meditation position.
4. Pranayama or controlled breathing exercises.
5. Pratyahara which indicates control of senses.
6. Dharana or concentration.
7. Dhyana or meditation and
8. Samadhi, the ultimate bliss.
This discipline of yoga described by Pantajali is commonly called Ashtanga Yoga. However, over the decades, Yoga has evolved into many different styles and intensities. Most yoga practices in the Western world consist of practice of Hatha Yoga: gentle exercise, stretching poses, controlled breathing and meditation.
Cardiovascular disease is the leading cause of death in the United States for both men and women. It claims more lives each year than cancer, chronic lower respiratory diseases, accidents, and diabetes mellitus combined. According to the CDC, in 2006, 631,636 people died of heart disease in the US. Almost 450,000 of these deaths were attributed to coronary artery disease. It is estimated that almost 800,000 Americans have a first heart attack each year, while another 470,000 who have already had one or more heart attacks have another attack. Heart disease costs over $300 billion each year, which includes the cost of health care services, medications, and lost productivity.
The major risk factors of cardiovascular disease are inactivity, obesity, hypertension, diabetes, abnormal lipid profile and chronic inflammation. Yoga appears to have beneficial effect on all of these. In a review of 37 studies from six countries, 75% of the studies showed improvement in blood pressure with yoga or yoga-based interventions. Overall, these studies demonstrated a 4.9% to 24.2% decline in diastolic blood pressure and a 2.6% to 21.3% decline in systolic blood pressure with yoga. There was also a decrease in resting heart rate and breathing rate. In 18 clinical trials between 1970 and 2004, yoga practice was associated with a 1.5% to 13.6% reduction in body weight. There have been at least 15 international studies demonstrating positive effects on the lipid profile – yoga practice was associated with a 5.8% to 25.2% decrease in total cholesterol, 22.0% to 28.5% reduction in fatty triglycerides, and a 12.8% to 26.0% reduction in the bad LDL cholesterol. Some studies have also demonstrated an increase in the good HDL cholesterol levels. Almost 13 studies have focused on studying the effects of yoga on diabetes mellitus and markers of insulin resistance. On an average, yoga practice was associated with a 5.4 to 33.4% reduction in fasting glucose, 24.5 to 27.0% reductions in postprandial glucose, and 13.3 to 27.3% reduction in glycohemoglobin (HbA1c). Studies have also demonstrated improvement in metabolic syndrome.
Yoga exercises will burn calories to help reduce weight. The mind-body connection benefits of yoga are backed by irrefutable scientific evidence. Yoga techniques improve physical and mental health through down-regulation of the hypthalamic-pituitary-adrenal axis and the sympathetic nervous system. Yoga has been found to decrease markers of inflammation such as high sensitivity C-reactive protein as well as inflammatory cytokines such as interleukin-614 and lymphocyte-1B. There is attenuation of oxidative stress. There is also decreased tendency to clot and brain scans have shown higher levels of GABA (low levels of GABA are associated with anxiety and depression) after an one hour yoga session.
The benefits of yoga extend beyond the cardiovascular system. The gentle stretching exercises improve muscle, ligament and joint function. There is an increase in flexibility, strength and endurance. The body posture is also improved. Chronic conditions such as asthma and arthritis have shown improvement. There is also an anti-depressive and anti-insomnia effect. Overall, most practitioners of yoga claim that they not only feel fitter and energetic, but happier and more peaceful.
The National Institute of Health is actively supporting clinical trials on yoga. An online check regarding clinical trials on yoga revealed 140 trials on the NIH site, clinicaltrials.gov, for a multitude of medical conditions including breast cancer, multiple sclerosis, cystic fibrosis, brain tumors and heart failure. A recent report in the November 1, 2011 issue of the Annals of Internal Medicine reported that yoga practice for 12 weeks in adults with chronic or recurrent low back pain resulted in greater improvement than usual care for up to 12 months.
Yoga is generally considered to be safe in healthy people when practiced appropriately. Studies have found it to be well tolerated, with few side effects. Some yoga ‘inverted’ poses should be avoided by people with disc disease of the spine, glaucoma, retinal detachment, ear problems, severe osteoporosis, or cervical spondylitis. These poses should also be avoided by people with very high or very low blood pressure, risk or history of blood clots and severe atherosclerotic vascular disease. Care should also be taken to avoid certain poses during pregnancy.
Yoga is easy to learn and easy to perform. It can be performed individually at any time and without any constraints due to weather conditions. Further, individuals find that it is easier to stick to yoga than other exercise methods. It is also very safe. It is free of any religious or cultural shackles and can be learnt and performed by everyone.