IJCRR - 4(3), February, 2012
Download XML Download PDF
EVALUATION OF YOGA THERAPY FOR THE RISK FACTORS OF CARDIOVASCULAR DISORDERS-A
Author: Deepa.T, N.Thirrunavukkarasu
Abstract:Yoga and Meditation techniques are growing popular worldwide in preventing or reducing cardiovascular diseases. We reviewed the latest studies and recent literature concerning the use of yoga in the treatment of cardiovascular disorders. The studies of yoga therapy on acute and chronic hypertensive patients showed significant reduction in stress,stress related blood pressure, blood cholesterol level and body weight. The studies showed significant improvement in cardiovascular endurance and reduction in left ventricular mass. The purpose of this review is to evaluate the effect of yoga therapy on hypertension, obesity and coronary heart disease.
Yoga is an ancient cultural heritage of India, designed to bring balance and health to the physical, mental, emotional, and spiritual dimensions of the individual. Yoga is often depicted as a tree comprised of eight limbs, such as yama (universal ethics), niyama (individual ethics),asana (physical postures), pranayama (breath control), pratyahara(control of the senses), dharana (concentration), dyana(meditation), and samadhi (bliss)1 .Yoga is described as comprising a rich treasure of physical and mental techniques that can be effectively used to create physical and mental well-being through down-regulation of the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS). As shown in fig 1,The HPA axis and SNS are triggered as response to stress, leading to a cascade of physiologic, behavioral, and psychologic effects, as a result of the release of cortisol and catecholamines. The repeated firing of the HPA axis and SNS due to stress can lead to dysregulation of the system and ultimately produce diseases such as diabetes, autoimmune disorders, depression, substance abuse, and cardiovascular disorders. Numerous studies have shown yoga to have an immediate downregulating effect on both the SNS and HPA axis response to stress2 .
Yoga has been extensively studied for its various effects in reducing salivary cortisol, blood glucose, as well as plasma renin levels and 24-hour urine norepinephrine and epinephrine levels3 . yoga reverses the negative impact of stress on the immune system by increasing levels of immunoglobulin A as well as natural killer cells .Yoga has been found to be useful on reducing BMR4,5, improvement in respiratory capacity 6 and shift of autonomic balance toward parasympathetic nervous system dominance, possibly via direct vagal stimulation7 . It is also found to be useful in treatment of diabetes8 , asthma9 , epileptic seizures10 and in anxiety disorders 11 .Yoga employs simple postures (asana), controlled breathing exercise(Pranayama)and meditation admixed in varying proportions.
History of yoga The origin of yoga is estimated to date back to the period between 200 BC and 300 AD, was written by a historically renowned yoga teacher and Hindu philosopher named Patanjali. The ancient Indian classic on the practice of yoga, Gherananda–Samhita, mentioned out of 840,000 asanas, only 84 are in contemporary common practice. Of these, only 32 are recommended by this ancient text as being useful for regular practice28 . Pranayama involves a slow deep inspiration and the breath is held momentarily in full inspiration, followed by slow and spontaneous exhalation.
Hypertension and its management
Hypertension is the most common cardiovascular disease affecting more than one billion people throughout the world. It is a major contributor of stroke, ischemic heart disease, heart failure, renal dysfunction and blindness43.The seventh Joint National Committee on Detection, Evaluation, and treatment of high blood pressure (JNC VII 2003) defined hypertension as a systolic blood pressure (SBP) of 140mmHg or greater and diastolic blood pressure (DBP) of 90mmHg or higher. Hypertension is further classified into two groups based on etiology as essential or primary hypertension and secondary hypertension. Essential hypertension is diagnosed when there is strong family history and no identifiable cause can be found42 . Hypertension is almost always easy to treat but difficult to keep under control as blood pressure is a continuous variable12. The goal of treatment is to lower the blood pressure as early as possible and maintain it, thereby preventing major complications of systemic hypertension. Drugs are prescribed as first line choice of treatment due to their significant, cost-effective, immediate action on reducing blood pressure. The utility of these agents is limited by the narrow range between therapeutic and toxic doses. These often produce dose dependent side effects, adverse reactions and rebound or overshoot hypertension when drug therapy is discontinued suddenly.13The side - effects, life long medical regimen, and cost of drugs have stimulated the search for a non-drug therapy as a primary treatment or as adjunctive therapy.Many non-pharmacological measures, such as 100mmol/day reduction in sodium intake, have been associated with a decline in blood pressure of about 5–7mmHg (systolic)/2.7mmHg (diastolic) in hypertensive subjects. Regular physical exercise such as walking is added along with drugs for its effect in managing hypertension. Many mindbody interventional methods like relaxation, biofeedback, stress management along with lifestyle modification have been shown as potential treatment for BP. Relaxation therapies alone doesn‘t show significant result in reducing BP. Hence progressive muscle relaxation techniques are not considered as an effective treatment method for high blood pressure . In contrast, Stress management therapies have some merits but are not widely available nor practiced. Studies on various non- drug modalities have shown more benefits from Yoga and Meditation in long term control of hypertension than any other modality.14,15 .
Yoga therapy on hypertension
It has been demonstrated in a randomised controlled Studies ,that even a short period of yoga intervention (3 months ) is as effective as drug therapy in reducing high blood pressure16 and heart rate31. The mechanism of yoga-induced blood pressure reduction may be attributed to its beneficial effects on the autonomic neurological function. Impaired baroreflex sensitivity has been increasingly postulated to be one of the major causative factors of essential hypertension. Regular practice of yoga increase the baroreflex sensitivity and decrease the sympathetic tone, thereby restoring blood pressure to normal level in hypertensive subjects17. Similarly, the decrease in sympathetic activity seen with slow breathing might be beneficial in hypertension, where sympathetic activation has been linked to disturbed breathing patterns and increased chemoreflex activity29 . Meditation by modifying the state of anxiety reduces stress induced sympathetic over activity , decreases the arterial tone and peripheral resistance, that lead to reduction in diastolic blood pressure and heart rate. This ensures better peripheral circulation and blood flow to the tissues18,19 . Meditation is associated with reduced sympathetic adrenergic receptor sensitivity,which might affect cardiovascular response during stress. During meditation appearance of frontal midline theta rhythm in electroencephalogram reflects mental concentration as well as meditative state of relief from anxiety and is correlated negatively with sympathetic activation. This suggests a close relationship between autonomic functions and activity of medial frontal neural circuitry and possibility of controlling CNS functions through yoga and meditation20. Transcendental meditation (TM) practice improves mood state, adrenocortical activity and kidney functions and believed to reduce stress and shows significant reduction in ambulatory diastolic BP21 . Yoga on chronic hypertension Yoga has proven its effect in modifying secondary complications produced by chronic hypertension. Left ventricular hypertrophy is a common consequence seen due to systemic hypertension.This may lead to many chronic cardiac complications, such as myocardial ischaemia, congestive cardiac failure and impairment of diastolic function. Left ventricular hypertrophy due to systemic hypertension is indicated by the height of ?R‘ wave in lead I, aVL, V5 and V6 in electrocardiogram. In one study The height of ?R‘ wave was taken prior to yoga practice and three months after continuation of yoga practice. The height of ?R‘ wave has come down appreciably in some patients indicating the reduction of left ventricular mass22 . Effect of yoga on body weight Weight also has the strongest independent correlation with the risk of hypertension. Yoga has been found to be particularly helpful in the management of obesity23. A randomized controlled study revealed that practising yoga for a year helped significant improvements in the ideal body weight and body density3 . A retrospective observational study showed that a regular practice of yoga for 4 years was significantly associated with weight loss by overweight participants24. After 4-day residential yoga practice followed by 14 weeks of 1 h daily home practice, one study found a significant loss in mean body weight from 72.26 to 70.48 kg among subjects with risk factors for coronary artery disease25 . Other studies confirmed that yoga was associated with significant weight loss by subjects with Coronary artery disease. After one year yoga practice coronary artery diseased patients showed a 7% loss of body weight26 and in a study by Schmidt and colleagues, healthy adults lost an average of 5.7 kg after 3 months of yoga practice27 . Effect of yoga on coronary artery disease Systemic hypertension is one of the risk factor for developing coronary artery disease. Participants with risk factors of coronary artery disease showed reduction in all parameters such as Blood pressure, LDL, total cholesterol, triglycerides except high density lipoprotein.In a randomized controlled study, patients with angiographically proven coronary artery disease who practiced yoga exercise for a period of one year showed a decrease in the number of anginal episodes per week, improved exercise capacity and decrease in body weight28. Thus yoga exercise increases regression and retards progression of atherosclerosis in patients with severe coronary artery disease26. Subjects who practiced pranayama or controlled yogic breathing could achieve higher work rates with reduced oxygen consumption per unit work and without an increase in blood lactate levels. one study reported the effects of yoga training on cardiovascular response to exercise and found yoga training improved the exercise tolerance to cardiovascular effects. Yoga on the management of coronary artery disease showed reduction in sympathetic tone, decreased peripheral vascular resistance, improved cardiac output, reduction in heart rate , blood pressure, and improvement in cardiovascular endurance3 . Effect of Yogic Practices in Prevention of Diabetes Yogic practices reduce body fat and increase lean body mass, thereby help in improving insulin sensitivity32 . The reduction in free fatty acid levels have a significant effect on beta cell function. hence yogasanas by preventing beta cell exhaustion may prevent diabetes. studies have confirmed the benefit of yoga in the control of diabetes mellitus. All the studies showed a significant fall in the fasting and post-prandial blood glucose values within 3 months and continued to have a smooth and good control of diabetes during the period of the study as evidence by a normal glycosylated hemoglobin and blood glucose levels33. The drug requirements were significantly reduced. CONCLUSION The beneficial effects of yoga to the heart ailments is outstanding. However, the role of yoga in the management of the hypertension should be complementary to the conventional modes of treatment. Regular yoga practice involving simple postures, relaxation exercise and respiratory exercise combined with drug therapy showed superior results compared to those who did not practice yoga. The reviews showed that yoga had beneficial effects on reducing BP , blood cholesterol level and body weight .It also improves left ventricular function and cardiovascular endurance. Considering the scientific evidence discussed so far, we can postulate that the practice of yoga triggers neurohormonal mechanisms that bring about health benefits by suppressing sympathetic activity. hence we conclude that yoga can be beneficial in preventing cardiovascular disease and can play a complementary role to drug therapy for hypertension.Any persistent benefits require a long-term adherence to yoga therapy and subjects who have continued their programs even at home showed better results30 . Additional studies are needed to distinguish between the different types of yoga and their various techniques. The optimal duration, the type of yoga program, and intensity of the yoga program need to be described clearly in many studies as they can affect the final outcome.. Additional studies are needed to find the effect of yoga on long term as only a few follow up studies are available. All of these studies need to use rigorous study methodologies, including the use of larger sample sizes, randomized samples, and blinding of researchers. ACKNOWLEDGEMENT Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
1. Iyengar BKS. Light on Yoga. 2nd ed. New York: Schocken Books, 1976.
2. Alyson Ross et al, The Health Benefits of Yoga and Exercise:A Review of Comparison Studies, J Altern complem Medicine.2010
3. Bera TK, Rajapurkar MV. Body composition,cardiovascular endurance, and anaerobics power of yogic practitioner. Indian J Physiol Pharmacol 1993; 37:225–228.
4. Chaya MS, Kurpad AV, Nagendra HR, Nagarathna R., The effect of long term combined yoga practice on the basal metabolic rate of healthy adults. BMC Complement Altern Med. 2006 ;6: 28
5. Telles S, B. H. Hanumanthaiah, R. Nagarathna and H. R. Nagendra, Plasticity of motor control systems demonstrated by yoga training. Indian Journal of Physiology and Pharmacology 1994;38: 143–144.
6. Bhole MV, Karambelkar PV, Gharote ML.Effect of yoga practices on vital capacity. Ind J Chest Dis1970; 12: 32– 35.
7. Joseph, S., Sridharan, K., Patil, S. K. B., Kumaria, M. L., Selvamurthy, W., 1981). Study of some physiological and biochemical parameters in subjects undergoing yogic training. Indian journal of medical research.
8. Sahay,Role of yoga in diabetes.A review.JAPI 2007
9. Jain and talukdar,evaluation of yoga therapy program for patients of bronchial asthma.Singapore Med journal 1993
10. Deepak k, Manchanda, S. K., and Maheshwari, M. C. (1994),meditation improves clinical electroencephalographic measures in drug-resistant epileptics. Biofeedback and Self Regulation.
11. Gupta et al 2006 Gupta N,Khera S,Vempati RP,Sharma R,Bijlani RL.effect of yoga based lifestyle intervention on state and trait anxiety, Indian physiology and pharmacology 2006;50(1):41-47
12. Kaplan 2002 Kaplan NK. Kaplan‘s Clinical Hypertension, 8th edition .Lippincotts Williams and wilkins,Philadelphia,2002.
13. Marvin Moser and John.F.Setero.Resistant or Difficult-toControl Hypertension. N Engl J Med 2006; 355:385-392
14. Andrews G,MacMahon SW,Austin A,Byrne DG.Hypertension:comparison of drug and non-drug treatments.British Medical Journal (Clinical Residence Edition).1982 May 22;284(6328):1523-6
15. Anand MP. Non-pharmacological management of essential hypertension. Journal of Indian Medical Association 1999 Jun; 97(6):220-5.
16. Murugesan R, Govindarajalu N, Bera TK. Effect of selected yogic practices in the management of hypertension. Indian J Physiol Pharmacol 2000; 207–210.
17. Vijayalakshmi P, Madan Mohan, Bhavanani AB, Asmita Patil, Kumar Babu P.Modulation of stress induced by isometric hand grip test in hypertensive patients following yogic relaxation training. Indian J Physiol Pharmacol 2004; 48(1): 59-60.
18. Bhargava R, Gogate MG and Macarenhas JF. Autonomic responses to breathholding and its variations following pranayama. Indian J Physiol Pharmacol 1988; 32(4);257–264.
19. Gopal KS, Bhatnagar OP, Subramanian N, Nishith SD. Effect of yogasana and pranayamas on blood pressure, pulse rate and some respiratory functions.Indian J Physiol Pharmocol 1973; 17(3); 273–276.
20. Katya Rubia,The neurobiology of Meditation and its clinical effectiveness in psychiatric disorders
21. Richard P. Brown, yogic breathing and meditation:when the thalamus quiets the cortex and rouses the limbic system
22. Konar D, Latha R, Bjuvanesvaran JS. Cardiovascular response to headdownbody-up postural exercise (Sarvangasana). Indian J PhysiolPharmacol 2000; 44:392–400.
23. Udupa KN, Singh RH. The scientific basis of yoga. J Am Med Assn 1972Udupa KN, Singh RH. The scientific basis of yoga. J Am Med Assn 1972;220(10): 1365.
24. Kristal AR, Littman AJ, Benitez D, White E. Yoga practice is associated with attenuated weight gain in healthy, middle-aged men and women. Altern Ther Health Med. 2005;11:28–33.
25. Mahajan AS, Reddy KS, Sachdeva U. Lipid profile of coronary risk subjects following yogic lifestyle intervention. Indian Heart J. 1999;51:37–40.
26. Manchanda SC, Narang R, Reddy KS, Sachdeva U, Prabhakaran D, Dharmanand S, et al. Retardation of coronary atherosclerosis with yoga lifestyle intervention. J Assoc Physicians India. 2000;48:687–94.
27. Schmidt T, Wijga A, Von Zur Muhlen A, Brabant G, Wagner TO. Changes in cardiovascular risk factors and hormones during a comprehensive residential three month kriya yoga training and vegetarian nutrition. Acta Physiol Scand Suppl. 1997;640:158–62.
28. Yoga in cardiac health (A Review).Satyajit R. Jayasinghe.European Journal of Cardiovascular Prevention and Rehabilitation 2004, 11:369–375
29. Chacko.N.JosephSlow Breathing Improves Arterial Baroreflex Sensitivity and Decreases Blood Pressure in Essential Hypertension. Hypertension. 2005; 46: 714-718
30. Kyeongra Yang A Review of Yoga Programs for Four Leading Risk Factors of Chronic Diseases, Evid Based Complement Alternat Med. 2007 December; 4(4): 487–491.
31. Indla Devasena et al, Effect of yoga on heart rate and blood pressure and its clinical significance. Int J Biol Med Res. 2011; 2(3): 750-753. 32.
32.Sahay BK. Yoga and Diabetes in Novo Nordisk Diabetes Update 94 Proceedings. Ed. Anil Kapur, Publ. Health CareCommunications, Bombay, 1994;159-68. 33.
33.Sahay BK, Murthy KJR. Raju PS. Madhavi S, et al. Long term follow up on effect of yoga in diabetes in Baba Shole ed Diabetes Research in Clinical Practice. Abstracts of XIII congress of IDFAbstract p65-004-293-655.
34. Agarwal, R. C.,et al. Effects of Shavasana on vascular response to a cold pressor test in hyper-reactors. Indian Heart Journal 1977, 29(4):182-185
35. Bijlani RL, Vempati RP, Yadav RK, et al. A brief but comprehensive lifestyle education program based on yoga reduces risk factors for cardiovascular disease and diabetes mellitus. Journal of Alternative and Complementary Medicine 2005;Apr, 11(2):267-274
36. Damodaran A, Malathi A, Patil N, Shah N, Suryavansihi , Marathe S. Therapeutic potential of yoga practices in modifying cardiovascular risk profile in middle aged men and women.J Assoc Physicians India 2002 May;50(5):633-40
37. Geetanjali Sharma, Mahajan K. K,Luv Sharma. Shavasana-Relaxation technique to combat stress. Indian journal of physiology and pharmacology 2006.
38. Jennifer chodzinski. The effect of Blood pressure in hypertensive adults .Journal of undergraduate research 2006,vol 1,Issue 6.
39. Khanam AA, Sachdeva U, Guleria R, Deepak KK. Study of pulmonary and autonomic functions of asthma patients after yoga training. Indian J Physiol Pharmacol. 1996 Oct; 40(4):318-24.
40. Patel C, North WR. Randomised controlled trial of yoga and bio-feedback in management of hypertension. Lancet. 1975 Jul 19;2(7925):93–95
41. Stone RA, DeLeo J. Psychotherapeutic control of hypertension. New England Journal of Medicine. 1976 Jan 8;294(2):80–84. 42.
42.Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: Analysis of worldwide data. Lancet. 2005;365:217– 23.
43. Gupta R. Trends in hypertension epidemiology in India. J Hum Hypertens. 2004;18:73–8. 44. Jyotsana R. Bharshankar*, Rajay N. Bharshankar.Effect of yoga on cardiovascular system in subjects above 40 years. Indian J physio pharmacol 2003; 47 (2) : 202–206.
45. Harinath, K., Malhotra, A. S., Pal, K., Prasad, R., Kumar, R., Kain, T. C., et al. (2004). Effects of Hatha yoga and Omkar meditation on cardiorespiratory performance, psychologic profile, and melatonin secretion. Journal of Alternative and Complementary Medicine, 10(2), 261-268.