Int J Yoga. 2015 Jan­Jun; 8(1): 62–67.doi: 10.4103/0973­6131.146067 PMCID: PMC4278137

Effect of yoga regimen on lung functions including diffusion capacity in coronary artery disease patients: A randomized controlled study

Asha Yadav,  Savita Singh,  KP Singh,1 and  Preeti Pai

Department of Physiology, University College of Medical Sciences, Delhi, India

1Department of Medicine, University College of Medical Sciences, Delhi, India

Address for correspondence: Dr. Asha Yadav, Department of Physiology, University College of Medical Sciences, Dilshad Garden, Delhi ­

110 095, India. E­mail:

Copyright : © International Journal of Yoga

This is an open­ access article distributed under the terms of the Creative Commons Attribution­Noncommercial­Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.



Lung functions are found to be impaired in coronary artery disease (CAD), congestive heart failure, left ventricular dysfunction, and after cardiac surgery. Diffusion capacity progressively worsens as the severity of CAD increases due to reduction in lung tissue participating in gas exchange.

Aims and Objectives:

Pranayama breathing exercises and yogic postures may play an impressive role in improving cardio­ respiratory efficiency and facilitating gas diffusion at the alveolo­capillary membrane. This study was done to see the effect of yoga regimen on lung functions particularly diffusion capacity in CAD patients.

Materials and Methods:

A total of 80 stable CAD patients below 65 years of age of both sexes were selected and randomized into two groups of 40 each. Group I CAD patients were given yoga regimen for 3 months which consisted of yogic postures, pranayama breathing exercises, dietary modification, and holistic teaching along with their conventional medicine while Group II CAD patients were put only on conventional medicine. Lung functions including diffusion capacity were recorded thrice in both the groups: 0 day as baseline, 22nd day and on 90th day by using computerized MS medisoft Cardio­respiratory Instrument, HYP’AIR Compact model of cardio­respiratory testing machine was manufactured by P K Morgan, India. The recorded parameters were statistically analyzed by repeated measures ANOVA followed by Tukey's test in both the groups. Cardiovascular parameters were also compared before and after intervention in both the groups.


Statistically significant improvements were seen in slow vital capacity, forced vital capacity, peak expiratory flow rate, maximum voluntary ventilation, and diffusion factor/ transfer factor of lung for carbon monoxide after 3 months of yoga regimen in Group I. Forced expiratory volume in 1st sec (FEV1), and FEV1 % also showed a trend toward improvement although not statistically significant. HR, SBP and DBP also showed significant improvement in Group­I patients who followed yoga regimen.


Yoga regimen was found to improve lung functions and diffusion capacity in CAD patients besides improving cardiovascular functions. Thus, it can be used as a complimentary or adjunct therapy along with the conventional medicine for their treatment and rehabilitation.

Keywords: Coronary artery disease, pulmonary function tests, pranayama, yoga regimen


Coronary artery disease (CAD) is defined as impairment of heart function due to inadequate blood flow to the heart against its demand, caused by obstructive changes in the coronary circulation to the heart. Prevalence of CAD is greatly increasing in our country for the last several years and is expected to assume epidemic proportions soon. CAD causes more deaths and disabilities, and incurs greater economic costs than any other illness in the developed as well as developing countries. Projections based on the Global Burden of Disease Study estimate that by the year 2020, the burden of athero­thrombotic cardiovascular disease in India would surpass that in any other region in the world. [1] Studies in India have documented a five­fold higher prevalence of coronary heart disease in the urban as compared to the rural population.

[2] Over the last three decades, progress in coronary artery bypass grafting and percutaneous interventions has improved the prognosis of CAD, but has not been able to address the basic etiopathology of CAD. [3,4] These are merely providing palliative relief at a high cost.

The lungs are linked in series with the cardiac pump, and they are not only influenced by mechanical alterations in pump function but also by neuro­humoral modulators and cytokines involved in the pathogenesis of various heart diseases. [5,6] It has also been proposed that increased levels of circulating cytokines such as tumor necrosis factor­α and interleukin­6 in CAD patients may induce changes in lung parenchyma. [7] High left atrial pressure may also induce chronic remodeling of the pulmonary vasculature and its wall thickening. There may also be an enhanced degree of airway reactivity. [8] Elevation of the capillary pressure causes alveolar­capillary membrane stress failure (i.e., increase in

capillary permeability to water and ions, and disruption of local regulatory mechanisms for gas exchange), leading to a decrease in membrane conductance, an increase in capillary blood volume and subsequent impairment of diffusion capacity. [9,10] Diffusion factor of the lung for carbon monoxide (DLCO) may give an early indication of alveolar­capillary membrane dysfunction in CAD patients as data is lacking in stable patients of CAD.

There is a growing incidence of anxiety and stress related diseases like CAD for which conventional medicine offers only relief from symptom, not from the disease. The new millennium has heralded an unprecedented increase in such disorders and appropriate preventive and remedial measures are needed to be taken. Yogic exercises and pranayama may improve breathing patterns due to which respiratory bronchioles may be widened and perfusion of a large number of alveoli can be carried out efficiently. Yogic regimen may change the milieu at the bronchioles and the alveoli particularly at the alveolar­ capillary membrane to facilitate diffusion and transport. Studies done by several researchers showed that yogic lifestyle intervention decreases the stenosis of coronary artery, decreases the anginal episodes, retards atherosclerosis, decreases sympathetic activity and improves exercise tolerance. [11,12,13,14,15,16] Adiponectin, interleukin­6, and various other cardiovascular disease risk makers are also found to be modified by a short­term yoga­based lifestyle intervention in obese people. [17] We havenot come across any study showing the effect of a comprehensive yoga regimen on lung diffusion capacity in CAD patients to the best of our knowledge. Reports are available on improvement in lung functions and DLCO after yogic lifestyle intervention in asthma and chronic obstructive pulmonary disease (COPD) patients. [18,19]

As very few studies are available on the effect of yoga practices on lung functions and none on diffusion capacity in stable CAD patients, it is therefore, endeavored to study the effect of yogic regimen and lifestyle modification on lung diffusion capacity and other lung functions in patients with stable CAD.

MATERIALS AND METHODS                                                                                                        

A total of 80 patients with stable CAD of age group 45-­65 years (55.78 ± 8.95) were recruited from the Outpatient Department of Medicine, Guru Teg Bahadur Hospital, Delhi. All the patients were on regular conventional drug therapy. Most of them were on angiotens in ­converting enzyme inhibitors of calcium channel blockers along with aspirin. The subjects were selected on the basis of certain inclusion and exclusion criteria.

Inclusion criteria

Angiographically proven CAD Stable CAD for the last 2­6 years Middle socioeconomic class.

Exclusion criteria

History of any previous illness such as stroke, unstable angina, myocardial infarction, tuberculosis, diabetes mellitus, and renal disease

Any disease known to affect lung function as well as the course of CAD such as asthma and COPD Any history of smoking as it is a confounding factor.


This was a prospective randomized parallel group controlled study on patients with CAD, conducted in the cardio­respiratory lab of the Department of Physiology, University College of Medical Sciences (UCMS), Delhi. The ethical clearance from the Ethical Committee of the institution was obtained before starting the study. All the subjects underwent complete physical and clinical assessment as given in the performa.

Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean blood pressure (MBP) were also recorded in both the groups. Informed and written consent from each subject was taken before recruiting him/her in the study.

Due to the nonavailability (to the best of our knowledge) of any clearcut article on the effect of yogic intervention on DLCO, sample size of 80 was arbitrarily decided on the basis of observations mentioned by other researchers on other parameters of pulmonary function tests (PFTs) such as FEV1, forced vital capacity (FVC), and peak expiratory flow rate (PEFR). After the initial screening for selection criteria, the selected 80 CAD patients were randomized into two groups of 40 each according to a computer generated randomization list ( After this all the patients in both the groups underwent a baseline recording of PFTs and single breath DLCO in the cardio­pulmonary lab of Department of Physiology, UCMS. PFTs were recorded thrice in all the subjects and the best of the three was considered for analysis. After the basal recording Group I CAD patients underwent yoga regimen which included yogic postures, pranayama, dietary modifications and holistic teaching [Table 1] along with the conventional medicine while Group II patients were put only on conventional treatment.

Blinding and masking

As this was an interventional study double blinding was not possible. Here, the statistician who did the randomization, data analyst, and the researcher who carried out the assessments were blinded to the intervention and treatment status of the patients.

Intervention for the yoga group

All the patients in Group I followed yoga regimen daily for 3 months (90 days). A yoga instructor taught them yogasanas and pranayamas daily for 60 min (6 days/week) in the Yoga Lab of the Physiology Department. This was followed by lectures and group discussions. These sessions were aimed at understanding the need for lifestyle change, weight management and stress and anxiety management their diet was also modified and protein rich pulses, green vegetables, juicy fruits, and very less fat were included as per recommended by the dietician. After this they were asked to practice the whole yoga regimen at home for the next 10 weeks. Compliance was checked telephonically once in 3 days and they were called to the lab weekly for the follow­up.

Intervention for the control group

Group II patients continued their conventional medical treatment after the baseline measurements of lung function tests and they were also put on yoga regimen once they have completed their 3 months follow­up as controls.

Test procedure

Recording of all the parameters of PFTs in both the groups were done thrice during the study period: First on 0 day as basal recording and then repeat recordings were taken on 22nd day and on 90th day after the

intervention. Different parameters which were recorded were: Slow vital capacity (SVC), FVC, forced expiratory volume in 1st sec (FEV1), FEV1 /FVC ratio, PEFR, maximum voluntary ventilation (MVV),

and single breath DLCO. These lung functions were assessed by using computerized MS medisoft Cardio­ respiratory Instrument, HYP’AIR Compact model of cardio­respiratory testing machine was manufactured by P K Morgan, India. The data was analyzed and the results were shown on the computer screen. A total of three tests were performed for all the parameters of PFTs and the best of the three fulfilling the criteria of reproducibility and vitality was considered for analysis. Cardiovascular parameters such as HR, SBP, DBP, and MBP were recorded again in both the groups 90 days of intervention.

Statistical analysis

The data was analyzed intergroup as well as intragroup by using SPSS (Statistical Package for the Social Sciences)is a software used for statistical analysis and is developed by IBM. The baseline values of the two groups were checked for normal distribution by nonparametric Kolmogorov­Smirnov test. PFTs and

DLCO within the groups repeated thrice were compared by using repeated measures ANOVA followed by Tukey's test. Significance was considered when P < 0.05. For comparison of PFTs and diffusion capacity between the two groups, unpaired Student's t­test was applied. Cardiovascular parameters ­ HR, SBP, DBP and MBP were compared after 90 days of intervention in both the groups by using paired student's t­test.


The mean ± standard deviation of SVC, FVC, FEV1, FEV1 %, PEFR, MVV, and DLCO in Group I CAD patients before yogic regimen and after 22nd and 90th day of yogic regimen are given in  Table 1. These subjects showed a significant improvement in almost all the parameters of PFTs and in diffusion capacity

(DLCO). The PFTs of CAD patients who were on conventional medicine only served as controls are shown in  Table 2. These patients did not show significant improvement in lung functions on 22nd day and

90th day.  Table 3 is depicting the intergroup comparison of these subjects and controls after 90 days of intervention where Group I CAD patients followed yogic regimen along with conventional medicine while Group II patients were only on conventional medicine. Patients on yogic regimen showed significant improvement in SVC, FVC, FEV1, PEFR, MVV, and DLCO.

Group I patients who followed yoga regimen showed significant improvement in all the cardiovascular parameters (HR, SBP, and DBP) after 90 days while Group II patients who were on conventional treatment did not show much improvement [Table 4].


In this study, an improvement in almost all the parameters of PFTs ­ SVC, FVC, FEV1 %, PEFR, MVV, and DLCO was observed in CAD patients after following 3 months of yoga regimen. These improvements are statistically significant in CAD patients on yoga with conventional medicine as compared to patients mon conventional medicine only.

This could be because of reduction of sympathetic reactivity attained with yogic training which may allow broncho­dilatation by correcting the abnormal breathing patterns and reducing the muscle tone of inspiratory and expiratory muscles. Due to improved breathing patterns, respiratory bronchioles may be widened and perfusion of a large number of alveoli can be carried out efficiently. [20] Yogic practice covers the entire field of our existence from physical, sensory, emotional, mental and spiritual to the highest self­realization. One of the hallmarks of yoga is balance ­ which is of both body and mind. Yoga improves the circulation and there is better perfusion of tissues. It increases the strength of respiratory muscles and reduces sympathetic reactivity thereby helps to reduce stress and anxiety which aggravate the severity of CAD.

The further advantage of yogic breathing lies in the fact that it is more a vertical breathing. By this vertical breathing all the alveoli of both the lungs open out evenly. Due to the even expansions of all the alveoli, a vast expense of alveolar membrane is available for exchange of gases. The larger the surface available for the process of diffusion, the better is the process. [21] Generally a small portion of lung capacity is been utilized. This inadequate supply of oxygen results in improper waste disposal from the body. The body functions are slowed down and the cells fail to regenerate themselves due to lack of sufficient energy. Pranayama, a well regulated breathing exercise increases the depth of breathing and expands lungs more than normal and recruits previously closed alveoli. Moreover, endurance power of the lung muscle also improves after adopting yoga. [22]

Ornish et al. showed short term and long term benefits of lifestyle changes (without using cholesterol lowering drugs) on coronary lesions and clinical manifestations of CAD. [14] Manchanda et al. showed similar benefits in Indian patient population in both these studies, number of subjects were small. [11] Recent study done in Global Hospital and Research Centre at Mt. Abu on 123 CAD patients and 360 coronary lesions showed a significant improvement not only in hormonal profile (which showed increased levels of endorphins, serotonin and decreased level of catecholamine), lipid profile, quality of life, but also showed a significant regression of atherosclerotic lesions angiographically in the yoga group. [23] We have also seen significant improvement in cardiovascular parameters such as HR, SBP, and DBP after 90 days yoga regimen in CAD patients.

Very few reports are available which document an improvement in lung functions and prevention of complications after following yoga based lifestyle modification. Our previous pilot study on CAD patients reported an improvement in PEFR, ratio of FEV1 :FVC (FEV1 %), MVV, and forced mid­expiratory flow (25­75) after following 2 weeks of pranayama breathing exercises. [24] The limitation of this study were that the sample size was small, patients performed only pranayama and DLCO could not be recorded. In the present study, the subject size was bigger and they followed a proper yoga based lifestyle which included yogic postures, pranayama, diet management along with holistic teaching for a longer duration, that is, 3 months. Yogic exercises and pranayama may improve lung functions and prevent serious cardio­ respiratory complications by emphasizing optimal physical and mental conditioning. Yogic lifestyle modification therapy can be used as an adjunct to pharmacological treatment in CAD patients to achieve optimal results.

Strength of the study

Strength of our study is that it is first randomized control trial depicting the improvement in PFTs especially in diffusion capacity after following a longer duration of yoga regimen (3 months) under the guidance of a yoga instructor. Cardiovascular parameters ­ HR, SBP, DBP and MBP were compared after

90 days of intervention in both the groups by using paired student's T­test.

Limitations of the study

We have recruited CAD patients irrespective of their gender so the differences on the basis of gender have not been seen in this study. Cardiovascular parameters such as HR, SBP, DBP, and MBP were recorded before and after intervention but the correlation between respiratory and cardiovascular parameters were not done in this study.


In spite of tremendous advancement in medical technology conventional medicine has proved ineffective in tackling many disorders which have psychosomatic origin. Complementary therapy like yogic exercises and pranayama breathing can be encouraged in CAD patients for their treatment and rehabilitation.


The study was sponsored by grants ­in­ aid from Central Council for Research in Yoga and Naturopathy (CCRYN), Department of Ayush, Ministry of Health and Family Welfare, New Delhi. We express our sincere gratitude and thanks to all our patients for keeping faith in us and following the yogic regimen as instructed.


Source of Support: Nil

Conflict of Interest: None declared.



  1. Murray CJ, Lopez AD. Alternative projections of mortality and disability by cause 1990­2020: Global

Burden of Disease Study. Lancet. 1997;349:1498–504. [PubMed: 9167458]

Chadha SL. Urban­rural differences in prevalence of coronary heart disease and its risk factors. Curr

Sci. 1998;74:1069–73.

  1. Bravata DM, Gienger AL, McDonald KM, Sundaram V, Perez MV, Varghese R, et al. Systematic review: The comparative effectiveness of percutaneous coronary interventions and coronary artery bypass graft surgery. Ann Intern Med. 2007;147:703–16. [PubMed: 17938385]
  2. Boden WE, O’Rourke RA, Teo KK, Hartigan PM, Maron DJ, Kostuk WJ, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med. 2007;356:1503–16. [PubMed: 17387127]
  3. Remetz MS, Cleman MW, Cabin HS. Pulmonary and pleural complications of cardiac disease. ClinChest Med. 1989;10:545–92. [PubMed: 2689066]
  4. Hosenpud JD, Stibolt TA, Atwal K, Shelley D. Abnormal pulmonary function specifically related to congestive heart failure: Comparison of patients before and after cardiac transplantation. Am J Med.1990;88:493–6. [PubMed: 2337106]
  5. Saadeddin SM, Habbab MA, Ferns GA. Markers of inflammation and coronary artery disease. Med SciMonit. 2002;8:RA5–12. [PubMed: 11782689]

8. Braith RW, Welsch MA, Feigenbaum MS, Kluess HA, Pepine CJ. Neuroendocrine activation in heart failure is modified by endurance exercise training. J Am Coll Cardiol. 1999;34:1170–5.[PubMed: 10520808]

Agostoni P, Bussotti M, Cattadori G, Margutti E, Contini M, Muratori M, et al. Gas diffusion and alveolar­capillary unit in chronic heart failure. Eur Heart J. 2006;27:2538–43. [PubMed: 17028107]

  1. Guazzi M. Alveolar­capillary membrane dysfunction in chronic heart failure: Pathophysiology and therapeutic implications. Clin Sci (Lond) 2000;98:633–41. [PubMed: 10814599]
  2. 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. [PubMed: 11273502]
  3. Joshi LN, Joshi VD, Gokhale LV. Effect of short term ‘Pranayam’ practice on breathing rate and ventilatory functions of lung. Indian J Physiol Pharmacol. 1992;36:105–8. [PubMed: 1506070]
  4. Patel C, Marmot MG, Terry DJ, Carruthers M, Hunt B, Patel M. Trial of relaxation in reducing coronary risk: Four year follow up. Br Med J (Clin Res Ed) 1985;290:1103–6. [PMCID: PMC1418743]
  5. Ornish D, Scherwitz LW, Billings JH, Brown SE, Gould KL, Merritt TA, et al. Intensive lifestyle changes for reversal of coronary heart disease. JAMA. 1998;280:2001–7. [PubMed: 9863851]
  6. Yogendra J, Yogendra HJ, Ambardekar S, Lele RD, Shetty S, Dave M, et al. Beneficial effects of yoga lifestyle on reversibility of ischaemic heart disease: Caring heart project of International Board of Yoga. J Assoc Physicians India. 2004;52:283–9. [PubMed: 15636328]
  7. Smith C, Fowler S. Efficacy of breathing and coughing exercises in the prevention of pulmonary complications after coronary artery surgery. Chest. 1995;107:587–8. [PubMed: 7842810]
  8. Sarvottam K, Magan D, Yadav RK, Mehta N, Mahapatra SC. Adiponectin, interleukin­6, and cardiovascular disease risk factors are modified by a short­term yoga­based lifestyle intervention in overweight and obese men. J Altern Complement Med. 2013;19:397–402. [PubMed: 23210469]
  9. 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;40:318–24. [PubMed: 9055100]
  10. Singh S, Soni R, Singh KP, Tandon OP. Effect of yoga practices on pulmonary function tests including transfer factor of lung for carbon monoxide (TLCO) in asthma patients. Indian J Physiol Pharmacol.2012;56:63–8. [PubMed: 23029966]
  11. Soni R, Munish K, Singh K, Singh S. Study of the effect of yoga training on diffusion capacity in chronic obstructive pulmonary disease patients: A controlled trial. Int J Yoga. 2012;5:123–7. [PMCID: PMC3410191] [PubMed: 22869996]
  12. Rai L. A Physiological Approach to Yoga. Gurgaon, India: Anubhav Rai Publishers; 1996. Discovering Human Potential Energy: Health, Stress, Illness, Lifestyle and Disease Reversal
  13. Chanavirut R, Khaidjapho K, Jarce P, Pongnaratorn P. Yoga exercise increases chest wall expansion and lung volumes in young healthy Thais. Thai J Physiol Sci. 2006;19:1–7.
  14. Gupta SK, Sawhney RC, Rai L, Chavan VD, Dani S, Arora RC, et al. Regression of coronary atherosclerosis through healthy lifestyle in coronary artery disease patients ­ Mount Abu Open Heart Trial. Indian Heart J. 2011;63:461–9. [PubMed: 23550427]
  15. Yadav A, Singh S, Singh KP. Role of Pranayama breathing exercises in rehabilitation of CAD patients
  16. ­ A pilot study. Indian J Tradit Knowledge. 2009;8:455–8.



Effects of yoga training in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

Xun-Chao Liu1,2*, Lei Pan3*, Qing Hu2, Wei-Ping Dong2, Jun-Hong Yan4, Liang Dong1

1Department of Respiratory  Medicine, Qilu Hospital,  Shandong  University,  Jinan, Shandong  250012, China; 2Department of Respiratory  Medicine, Heze Municipal Hospital,  Heze, Shandong 274031, China; 3Department of Respiratory and Critical Care Medicine, 4Department of Clinical Medical Technology, Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, China

*These authors contributed equally to this work.

Correspondence to: Liang Dong,  MD.  Department of Respiratory  Medicine,  Qilu  Hospital  of Shandong  University,  107# Wenhua Xi Road, Jinan

250012, China. Email:


Introduction: Currently, several studies have assessed the effect of yoga training  on the management of chronic  obstructive  pulmonary  disease (COPD), but these studies involved a wide variation of sample and convey inconclusive results. Hence,  the present  study was performed  a systematic review and meta-analysis to investigate the efficacy of yoga training in COPD patients.

Methods:  PubMed,  EMBASE, the Cochrane Library, Google Scholar, and databases were searched for relevant  studies. The  primary  outcomes  were forced expiratory  volume in one second (FEV1), FEV1%  predicted  (% pred). Secondary outcomes  included 6-min walking distance (6 MWD), arterial oxygen tension  (PaO2), and arterial  carbon dioxide tension  (PaCO2).  Weighted mean differences (WMDs)  and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed with the I2 test.

Results: Five randomized  controlled  trials (RCTs) involving 233 patients fulfilled the inclusion criteria. Yoga training significantly improved FEV1  (WMD:  123.57 mL, 95% CI: 4.12-243, P=0.04), FEV1%  pred (WMD: 3.90%,  95%  CI: 2.27-5.54,  P<0.00001), and 6 MWD (WMD:  38.84 m, 95%  CI: 15.52-62.16,  P=0.001).

However,  yoga training  had no significant  effects on PaO2  (WMD:  1.29 mmHg,  95%  CI: –1.21-3.78, P=0.31) and PaCO2 (WMD:  –0.76 mmHg,  95% CI: –2.06-0.53, P=0.25).

Conclusions:  The  current  limited evidence suggested that yoga training has a positive effect on improving lung function  and exercise capacity and could be used as an adjunct  pulmonary  rehabilitation program in COPD patients.  However,  further  studies are needed  to substantiate  our preliminary  findings  and to investigate the long-term effects of yoga training.

Keywords: Chronic  obstructive pulmonary  disease (COPD); yoga; pulmonary  function; meta-analysis

Submitted  Feb 18, 2014.Accepted for publication May 13, 2014. doi: 10.3978/j.issn.2072-1439.2014.06.05

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Chronic  obstructive  pulmonary  disease (COPD) is an important cause of morbidity  and mortality  and poses a major public health  problem.  By 2020, COPD is predicted to  rank  as the  third  leading  cause of death  worldwide, whereas its social burden  will rank fifth (1-3). COPD is characterized  by irreversible  airflow obstruction, a gradual decline in lung function,  loss of lung tissue, reduced quality

of life, and high rates of mortality.  The  Global Initiative for Chronic  Obstructive Lung  Disease (GOLD) management includes  a reduction  in symptoms,  complications,  and exacerbations, improved exercise tolerance, improved health status, and reduced  mortality  (2). Recent  evidence-based clinical practice  guidelines  and statements  have shown that pulmonary  rehabilitation is widely accepted  as the  most effective non-pharmacotherapy in the  management of COPD (4). Research  have indicated  that  various exercises, such as upper  extremity  exercise (5), Tai Chi (6), and yoga training (7), can relieve dyspnea, improve lung function, and improve the quality of life of COPD patients. Furthermore, a physical therapist-assisted intensive  flexibility training that  focuses on stretching  and rib cage mobilization  can significantly improve 6-min walking distance (6 MWD)  (8).

Yoga originated  in ancient  India,  and may denote  the union  between  the  individual  self and the  transcendental self. The  body’s organs  and systems are cleansed through asanas (postures)  and pranayama (controlling  the  breath). Along with meditation, yoga asanas and pranayama have become  popular  in the  West,  and  the  practice  of yoga has become  “westernized.”  Postures  are taught  as ends in themselves,  that  is, to heal an illness, reduce  stress, or to look better  (9). Yogic exercises have been  shown to have positive  effects on  people  with  asthma  (10,11), cardiac diseases (12), diabetes  (13), tuberculosis  (14), depressive disorders (15), osteoarthritis (16), and pleural effusion (17).

A number  of clinical trials have suggested  that  yoga training  may improve  the pulmonary  function  of patients with COPD (18,19), but the quality of these studies have not been evaluated systematically. Therefore, we undertook a  s y s t e m a t i c  r e v i e w a n d  m e t a - a n a l y s i s o f a v a i l a b l e randomized  controlled  trials (RCTs) to assess the efficacy of yoga training  on pulmonary  function  and other  clinical endpoints  in patients with COPD.


Data sources and search strategy

Th e  f ol low in g  e lec tron ic  da ta ba se s w ere  se ar ch ed : PubMed,  Embase  databases,  Cochrane Central  Register of Controlled Trials, Google  Scholar,  and ClinicalTrials. gov (until Jan 2014). The  employed keywords were “yoga” and  “COPD,” or  “yoga” and  “COPD”. The  searches were limited  to English  publications  in humans  as well as RCTs. Bibliographies  of all potentially  relevant  studies, articles  (including  unpublished  data and meta-analyses), and  international guidelines  were  manually  searched. Furthermore, we also attempted to contact  the authors  of potentially relevant studies to obtain additional information.

Study selection

The  following inclusive selection  criteria  inPICOS order involved the following: (I) population:  patients with COPD; (II) intervention: yoga training  with  or  without  other

treatments; (III) comparison  intervention: any type  of control; (IV) outcome measures: the primary outcomes were forced expiratory volume in one second (FEV1) and FEV1% predicted  (% pred), whereas secondary  outcomes  included 6 MWD, arterial  oxygen tension  (PaO2),  and  arterial carbon dioxide tension (PaCO2); and (V) study design: RCT reported  in a full paper article.

Data extraction

For  each candidate  article,  Xun-Chao Liu  and Lei  Pan recorded  the characteristics  of the patients  being studied, i.e., first author,  year of publication,  COPD stage, sample size of the study population  (intervention/control), grade, staging, age, study design, Jadad scale, interventions (i.e., style of intervention, training  frequency,  exercise time, and duration),  outcome  parameters,  and their  results.  Liang Dong  checked all of the data. Disagreements were resolved by discussion.

Quality assessment and risk-of-bias  assessment

The  methodological quality of each research  was evaluated using the Jadad scale (20). A score ≤2 indicates low quality, whereas a score ≥3 indicates high quality (21). The  risk of bias was assessed using the Cochrane Handbook for Systematic Reviews of Interventions ( Two authors  (Xun-Chao Liu  and  Lei  Pan)  subjectively reviewed all studies and assigned a value of ‘high,’ ‘low,’ or ‘unclear’ to the following: (I) selection  bias (was there adequate  generation  of the  randomization sequence?  was allocation  concealment satisfactory?); (II) blinding  (i.e., performance bias and detection  bias) (was there  blinding of participants,  personnel,  and outcome  assessment?); (III) attrition  bias (were incomplete  outcome  data sufficiently assessed and dealt with?); (IV) reporting bias (was there evidence of selective outcome  reporting?);  and (V) other biases (was the study apparently  free of other problems  that could place it at a high risk of bias?).

Statistical analysis

This  systematic  review and  meta-analysis  is reported in accordance  with  the  Preferred  Reporting Items  for Systematic  Reviews and  Meta-Analyses  statement  (22). We  used Revman  version  5.1 software  for all data  and statistical analyses. For  continuous  outcomes,  the  pooled mean  difference  was calculated  by using  the  weighted




Articles identified through database

searching (n=10)

Additional articles through other

sources (n=1)




Excluded based on the

titles and abstracts (n=2)



Potentially relevant articles screened (n=9)



Reason for exclusion:

study design (n=4)

Studies included in qualitative synthesis (meta-

analysis) (Randomized controlled trials=5)

mean  difference  (WMD).  Heterogeneity was assessed with the I2  statistic and defined as low (I2≤25%),  moderate (25%<I2≤50%),  or high (I2>50%) (23,24). A random-effects model  was undertaken whether  heterogeneity was high or not.  Potential  publication  bias was not  assessed because of the  limited  number  of studies  (<10) included  in each analysis. A P value of <0.05 was considered  statistically significant. The  overall treatment effect was compared  with its minimal clinically important difference (MCID).


Bibliographic search

Figure 1 shows the  study  search  process  according  to PRISMA guidelines (22). Of the 11 studies retrieved from the initial search, six met our inclusion criteria  (7,18,19,25-27), but one study was excluded upon  secondary  analysis (27). The  reasons  for  exclusion  are  presented  in  Figure 1. Finally, five RCTs, which had a combined  cohort  size of

233 participants,  were selected for this meta-analysis,  and their  main  characteristics  are presented  in Table 1. The sample size per RCT  ranged from 30 to 100. These  studies were published  between 1978 and 2012, and their  duration ranged  from 12 weeks to 9 months.  Four  RCTs reported FEV1  (18,19) or FEV1%  (7,25), and two RCTs reported

6 MWD (7,25). Meanwhile,  two  RCTs reported  PaO2

and PaCO2 (18,19). The  mean  Jadad score of the  studies included  was 2.4 (SD=0.89). The  risk of bias analysis is presented  in Table 2.

Primary  outcomes

Two RCTs reported  primary  outcomes  as FEV1   (18,19), and another  two RCTs reported  FEV1%  pred  (7,25). The aggregate  results  of these  studies  suggested  that  yoga training  was associated  with  a significant  improvement in FEV1   [WMD:  123.57  mL,  95%  confidence  interval (CI): 4.12-243,  P=0.04] (Figure 2) and  FEV1%  (WMD:

3.90,  95%  CI:  2.27-5.54,  P<0.00001)  (Figure 3). The


test  for  heterogeneity  was not  significant  (FEV 1 : P  for  heterogeneity=0.68,  I 2 = 0%;  FEV  %:  P  for heterogeneity=0.39, I2=0%).  We  subsequently  performed sensitivity analyses to explore potential sources of heterogeneity. The  mean  changes  of FEV1   were greater than the MCID (>100 mL) (28).

Secondary outcomes

Meanwhile, two RCTs reported  results in terms of 6 MWD (7,25). The  aggregate results of these studies suggested that yoga training  was associated with a statistically significant improvement in 6 MWD (WMD:  38.84 m, 95% CI: 15.52-

62.16, P=0.001). The  results for the heterogeneity test was not significant (P for heterogeneity=0.08, I2=67%) (Figure 4). Subsequently,  the mean changes of 6 MWD were greater than  the  MCID (>26 m) (29). Two RCTs reported  PaO2 and PaCO2 (18,19), and these studies suggested  that  yoga training  was not associated with a significant difference  on PaO2 (WMD:  1.29 mmHg,  95%  CI: –1.21-3.78,  P=0.31) or  PaCO2 (WMD:  –0.76 mmHg,  95%  CI:  –2.06-0.53,


Table 1 Characteristics of randomized controlled trials included in the meta-analysis
Patients No. (I/C),     Age (years),               Form or style                                                                      Study design/ First author                                                                                                                    Protocol                  Duration

Grade, Staging       (Mean, I/C)    Yoga group     Control group                                                           Jadad score

Donesky-        29 (14/15), Stable,       69.9±9.5      Pranayama,     Usual-care        60 min/per time            12 w              RCT/2

Cuenco           NR                                                   asana               control               2 times/w

et al./2009

Soni                60 (30/30), Stable,         30-60        Pranayama,     Conventional    45 min/d                      2 mon             RCT/2

et al./2012      Mild or Moderate                             asana               treatment

Kulpati            75 (25/50), NR, NR    50.6/48.65    Pranayama      Conventional    30 min/per time            12 w              RCT/2

et al./1982                                                                                        treatment          2 times/d and breathing


Tandon           24 (12/12), Stable,           <65          Yogic                Physiotherapy  60 min/per time           9 mon             RCT/2

et al./1978      NR                                                   breathing         breathing          1-4 w: 3 times/w; exercises         exercises          5-8 w: 2 times/w; and postures                             9 w-9 mo: 2 times/w

Katiyar            45 (23/22), Stable,       53.3/51.1     Pranayama      Usual-care        30 min/per time           3 mon             RCT/4

et al./2006      severe                                                                       control               6 times/w

I/C, intervention/control; RCT, randomized controlled trial; NR, not reported.



Table 2 Assessing risk of bias
Sequence       Allocation                        Incomplete outcome    Selective outcome       Free of other

Study/year                                                                                Blinding

generation     concealment                         data addressed               reporting                      bias

Donesky-Cuenco et al./2009     Unclear               No                 No                    Yes                             Yes                       Unclear
Soni et al./2012                          Unclear               No                 No                    Yes                             Yes                       Unclear
Kulpati et al./1982                      Unclear               No                 No                    Yes                             Yes                       Unclear
Tandon et al./1978                     Unclear               No                 No                    Yes                             Yes                       Unclear
Katiyaret al./2006                          Yes                   No                Yes                    Yes                             Yes                       Unclear



P=0.25). The  test  for heterogeneity was not  significant

2                                                                                                                                     2

(PaO  : P for heterogeneity=0.47, I2=0%;  PaCO  : P for heterogeneity=0.23, I2=31%) (Figures 5,6).

of COPD treatment (30-33).  Studies  have indicated  an increase in tidal volume and FVC, reduction  in respiratory

rate,  increase  in  FEV  , FEV  %,  maximum  voluntary


1                    1






This study is the first meta-analysis  to evaluate the effects of yoga training  on COPD patients.  Our  results suggested that  yoga training  has a positive improvement effect on lung function  and exercise capacity and could be used as an adjunct  pulmonary  rehabilitation program  for COPD patients.

Currently, no  drugs  could  hinder  the  progress  of COPD, but  lung  training  and pulmonary  rehabilitation have been  shown  to  reduce  disability  in many  chronic respiratory  diseases and  have become  valuable means

ventilation,  and breath  holding  capacity after short-term yoga practice  (34,35). Furthermore, studies  suggested that  yoga training  may improve  exercise capacity, prevent lung function  decline, improve  quality of life, and reduce dyspnea in patients  with COPD (36,37). However,  these studies did not provide adequate  data or sufficient clinical evidence to support  the beneficial effects of yoga training on these relevant findings.

Our  results suggested that yoga training  improved  FEV1 or  FEV1%  pred  in four  studies  (7,18,19,25).  However, the results required  comparison  with the MCID, which is defined as the smallest change in the measurement used to evaluate the clinical significance of intervention effects. The



Figure  2 Meta-analysis  of randomized  controlled  trials evaluating effects of yoga training  on FEV1   by the random-effects model. FEV1,

forced expiratory volume in one second.




Figure  3 Meta-analysis of randomized  controlled  trials evaluating effects of yoga training  on FEV1%  by the random-effects model. FEV1,

forced expiratory volume in one second.




Figure 4 Meta-analysis of randomized  controlled  trials evaluating effects of yoga training  on 6WMD by the random-effects model. WMD, weighted mean difference.



Figure  5 Meta-analysis  of randomized  controlled  trials evaluating effects of yoga training  on PaO2  by the random-effects model. PaO2,

arterial oxygen tension.




Figure  6 Meta-analysis of randomized  controlled  trials evaluating effects of yoga training  on PaCO2 by the random-effects model. PaCO2,

arterial carbon dioxide tension.



MCID is claimed to be a 100-mL  change  in FEV1   from baseline (28), and the 123.57 mL increment in FEV1   in our study is greater  than  the MCID. This  result indicates that yoga training  can have a clinical effect on COPD patients. Unfortunately, we failed to compare  further  the  FEV1% pred with the MCID because of insufficient available data. Our  meta-analysis also found that yoga training  statistically improved  6 MWD in patients  with COPD. The  38.84 m change for 6 MWD was greater than the MCID (≥26 m) (29). However,  our meta-analysis  showed that  yoga training  did not affect arterial  blood gas analyses, which included  PaO2 and PaCO2.  PaO2 and PaCO2 are affected by various factors, such as temperature factors (38), breathing frequency  (39), varying levels of light  intensities  (40), sampling  location, blood volume, and inspection  time (41). We  believed that PaO2 and PaCO2  are not  suitable evaluation  parameters  of yoga training  in COPD patients because of their instability. However,  further  study  is needed  to  investigate  this noteworthy topic.

The  mechanisms  of yoga training  responsible  for its beneficial effects that  differ from other  forms of exercise have yet to be elucidated. Several factors may be responsible for the  beneficial effects seen in the  patients  undergoing yoga training  aside from exercises (42-45). Yoga training aids in toning  up general  body systems (42), increasing respiratory  stamina, relaxing chest muscles, expanding  the lungs, raising  energy  levels, and calming  the  body (43). Additionally,  yoga training  improves blood circulation  and increases the strength  of respiratory  muscles (44). Finally, yoga training  also helps patients  to breathe  more  deeply by utilizing  the shoulder,  thoracic,  and abdominal  muscles efficiently (45).

Yoga training  can provide a complementary strategy  for patients  with COPD. Apart from relaxing tense  muscles, yoga can also alleviate mental  pressure  (15). However further  studies are needed  to examine the effectiveness of

yoga training  compared  with other  breathing exercises. Our  study showed follow-up  durations  that  ranged  from

12 weeks to 9 months,  and the long-term effects of yoga training optimal exercise duration currently remain unknown.  Future  research  should  focus on  optimizing training  intensity,  duration,  and  frequency.  Moreover, it should  be emphasized  that  the  severity may greatly influence  the effect of yoga. However,  not all studies have noted  the  severity of COPD patients.  Further research should focus on the relationship  between  the severity and efficacy in COPD patients,  which can help to determine the  best yoga exercise prescription and the  best suitable patients.  Finally, most  studies lacked other  physiological outcome  measures,  such  as inflammatory  biomarkers, continuous  monitoring, sensitive measures  of change,  and peripheral  muscle strength.  Further studies that  focus on these will enrich clinical evidence regarding yoga.

Several limitations  are identified  in our  study.  First, included  trials significantly varied in terms of interventions protocol,  duration,  patient  populations,  severity,  and study quality,  which limit  the  conclusive extent  for the overall effectiveness of yoga training  on  FEV1,  FEV1% pred,  6 MWD, and blood gas analysis in COPD patients. Secondly,  our  analysis is based on  only five RCTs, and only a maximum of two studies were available for the main outcomes.  In addition,  studies ranged  from 1978 to 2012 hence  it encompasses  a wide time frame which may affect

the results as over the years better  drugs are available such anticholinergics to ameliorate  symptoms  of COPD and more  standardized  and accurate  methods  are available to measure  some clinical endpoints  such as lung function  and arterial  blood gas analysis. Moreover,  these studies have a wide variation  in patient  populations.  The  smaller sample size of trials  may have significantly  overestimated  the treatment effect. Finally, several missing and unpublished data may lead to bias.


Journal of Thoracic Disease, Vol 6, No 6 Jun 2014





Our  meta-analysis  suggested  that  yoga training  that  lasts from  12 weeks to 9 months  may improve  lung  function and functional  exercise capacity in patients  with COPD compared  with conventional  therapy. Moreover,  we suggest that yoga could be a useful adjunct pulmonary  rehabilitation program  for COPD patients.  To help  clarify the  issue, further  rigorously  designed,  larger-scale  trials should  be conducted  to evaluate the long-term effects of yoga training in COPD patients.





We  would like to thank  the authors  of the original  studies included in this meta-analysis.

Disclosure: The authors declare no conflict of interest.





  1. Viegi G, Pistelli F, Sherrill DL, et al. Definition,

epidemiology and natural history of COPD. Eur Respir J


  1. Vestbo J, Hurd SS, Agustí AG, et al. Global strategy for the diagnosis, management, and prevention  of chronic obstructive pulmonary  disease: GOLD executive summary. Am J Respir Crit Care Med 2013;187:347-65.
  2. Murray CJ, Lopez AD. Mortality by cause for eight regions of the world: Global Burden of Disease Study. Lancet 1997;349:1269-76.
  3. Qaseem A, Wilt TJ, Weinberger SE, et al. Diagnosis and management of stable chronic obstructive pulmonary disease: a clinical practice guideline update from the American College of Physicians, American College

of Chest Physicians, American Thoracic Society, and European Respiratory Society. Ann Intern  Med


  1. Pan L, Guo YZ, Yan JH, et al. Does upper extremity exercise improve dyspnea in patients with COPD? A meta- analysis. Respir Med 2012;106:1517-25.
  2. Yan JH, Guo YZ, Yao HM, et al. Effects of Tai Chi in patients with chronic obstructive pulmonary disease: preliminary evidence. PLoS One 2013;8:e61806.
  3. Donesky-Cuenco D, Nguyen HQ,  Paul S, et al. Yoga therapy decreases dyspnea-related distress and improves functional performance in people with chronic obstructive pulmonary  disease: a pilot study. J Altern Complement Med 2009;15:225-34.
  1. Yoshimi K, Ueki J, Seyama K, et al. Pulmonary rehabilitation program including respiratory conditioning for chronic obstructive pulmonary  disease (COPD): Improved hyperinflation  and expiratory flow during tidal breathing.  J Thorac Dis 2012;4:259-64.
  2. Garfinkel M, Schumacher  HR Jr. Yoga. Rheum Dis Clin

North Am 2000;26:125-32, x.

  1. Manocha R, Marks GB, Kenchington P, et al. Sahaja yoga in the management of moderate to severe asthma: a randomised  controlled  trial. Thorax  2002;57:110-5.
  2. Sabina AB, Williams AL, Wall HK, et al. Yoga intervention

for adults with mild-to-moderate asthma: a pilot study. Ann Allergy Asthma Immunol  2005;94:543-8.

  1. Jayasinghe SR. Yoga in cardiac health (a review). Eur J

Cardiovasc Prev Rehabil 2004;11:369-75.

  1. Malhotra V, Singh S, Tandon OP, et al. The beneficial

effect of yoga in diabetes. Nepal Med Coll J 2005;7:145-7.

  1. Visweswaraiah NK, Telles S. Randomized trial of yoga

as a complementary therapy for pulmonary  tuberculosis. Respirology 2004;9:96-101.

  1. Sharma VK, Das S, Mondal S, et al. Effect of Sahaj Yoga

on depressive disorders. Indian J Physiol Pharmacol


  1. Ernst E. Complementary or alternative therapies for osteoarthritis. Nat Clin Pract Rheumatol 2006;2:74-80.
  2. Prakasamma M, Bhaduri A. A study of yoga as a nursing intervention in the care of patients with pleural effusion. J Adv Nurs 1984;9:127-33.
  3. Tandon MK. Adjunct treatment with yoga in chronic

severe airways obstruction. Thorax  1978;33:514-7.

  1. Kulpati DD, Kamath RK, Chauhan MR. The influence of physical conditioning by yogasanas and breathing exercises in patients of chronic obstructive lung disease. J Assoc Physicians India 1982;30:865-8.
  2. Jadad AR, Moore RA, Carroll D, et al. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 1996;17:1-12.
  3. Kjaergard LL, Villumsen J, Gluud C. Reported methodologic quality and discrepancies between large and small randomized trials in meta-analyses. Ann Intern  Med


  1. Liberati A, Altman DG, Tetzlaff J, et al. The PRISMA statement for reporting systematic reviews and meta- analyses of studies that evaluate healthcare  interventions: explanation and elaboration.  BMJ 2009;339:b2700.
  2. Higgins JP, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med 2002;21:1539-58.
  3. Higgins JP, Thompson SG, Deeks JJ, et al. Measuring


inconsistency in meta-analyses. BMJ 2003;327:557-60.

  1. Katiyar SK, Bihari S. Role of pranayama in rehabilitation

of COPD patients–a randomized  controlled  study. Indian J Allergy Asthma Immunol  2006;20:98-104.

  1. Soni R, Munish K, Singh K, et al. Study of the effect of yoga training on diffusion capacity in chronic obstructive pulmonary disease patients: A controlled  trial. Int J Yoga


  1. Donesky D, Melendez M, Nguyen HQ,  et al. A responder analysis of the effects of yoga for individuals with COPD: who benefits and how? Int J Yoga Therap 2012:23-36.
  2. Donohue JF. Minimal clinically important differences in

COPD lung function. COPD 2005;2:111-24.

  1. Puhan MA, Chandra D, Mosenifar Z, et al. The minimal important difference of exercise tests in severe COPD. Eur Respir J 2011;37:784-90.
  2. Lacasse Y, Wong E, Guyatt GH,  et al. Meta-analysis of respiratory  rehabilitation in chronic obstructive pulmonary disease. Lancet 1996;348:1115-9.
  3. Singh V. Effect of respiratory exercises on asthma. The

Pink City lung exerciser. J Asthma 1987;24:355-9.

  1. Singh V, Wisniewski A, Britton J, et al. Effect of yoga breathing exercises (pranayama) on airway reactivity in subjects with asthma. Lancet 1990;335:1381-3.
  2. Ries AL, Bauldoff GS, Carlin BW, et al. Pulmonary Rehabilitation: Joint ACCP/AACVPR Evidence-Based Clinical Practice Guidelines. Chest 2007;131:4S-42S.
  3. Makwana K, Khirwadkar N, Gupta HC. Effect of short term yoga practice on ventilatory function tests. Indian J Physiol Pharmacol  1988;32:202-8.
  4. Joshi LN, Joshi VD, Gokhale LV. Effect of short term

‘Pranayam’ practice on breathing rate and ventilatory

functions of lung. Indian J Physiol Pharmacol


  1. Behera D. Yoga therapy in chronic bronchitis. J Assoc

Physicians India 1998;46:207-8.

  1. Fulambarker A, Farooki B, Kheir F, et al. Effect of yoga

in chronic obstructive pulmonary  disease. Am J Ther


  1. Bradley AF, Severinghaus JW, Stupfel M. Effect of temperature on PCO2 and PO2 of blood in vitro. J Appl Physiol 1956;9:201-4.
  2. Kapus J, Ušaj A, Kapus V, et al. The influence of reduced breathing during swimming on some respiratory and metabolic values in blood. KinSI 2002;8:14-8.
  3. Olanrewaju HA, Purswell JL, Collier SD, et al. Effect of varying light intensity on blood physiological reactions of broiler chickens grown to heavy weights. Int J Poult Sci


  1. Cunningham DJ, Cormack RS, O’Riordan JL, et al.

An arrangement for studying the respiratory  effects in man of various factors. Q J Exp Physiol Cogn Med Sci


  1. Udupa KN, Singh RH. The scientific basis of yoga. JAMA


  1. Chanavirut R, Khaidjapho K, Jaree P, et al. Yoga exercise increases chest wall expansion and lung volumes in young healthy thais. Thai J Physiol Sci 2006;19:1-7.
  2. Posadzki P, Parekh S. Yoga and physiotherapy: a speculative review and conceptual synthesis. Chin J Integr Med 2009;15:66-72.
  3. Yoga breathing techniques  (YBT) in chronic obstructive pulmonary  disease (COPD): a preliminary study. Int J Yoga Ther  2003;13:51