The efficacy of a comprehensive lifestyle modification programme based on yoga in the management of bronchial asthma: a randomized controlled trial

Although the efficacy of yoga in treating bronchial asthma[1] has been investigated since at least the 1960s [2–9], most of the previous studies have been uncontrolled, and have evaluated only a few selected yogic postures or breathing exercises. To the best of our knowledge, there is only one randomized controlled trial which has evaluated the efficacy of an integrated package consisting of yogic postures, breathing exercises, cleansing techniques, meditation, devotional sessions and lectures[10]. However, even this study did not investigate the mechanisms by which yoga improves the symptoms of bronchial asthma. The present randomized controlled trial was undertaken to study the efficacy of a comprehensive lifestyle modification and stress management program based on yoga in subjects having mild or moderate bronchial asthma. An attempt has also been made to monitor some immunological indicators of severity of disease and mast cell activation.

The values of the outcome measures at different time points during the study are given in Tables 3, 4, 5 and 6 and Figures 1, 2 and 3.

Parameter	Group	Week 0	Week 2	Week 4	Week 8	p -value
PEFR	Yoga	68.6 ± 18.4	76.5 ± 20.5*	81.5 ± 20.9‡	85.3 ± 20.7‡	0.000
	Control	57.4 ± 19.7	58.2 ± 22.0	56.9 ± 26.2	56.2 ± 22.0
FEV1	Yoga	70.2 ± 17.4	73.9 ± 19.6	76.1 ± 20.1	77.9 ± 17.2*	0.009
	Control	62.5 ± 19.2	63.1 ± 20.5	60.5 ± 21.6	59.9 ± 19.1
FVC	Yoga	78.7 ± 13.4	78.0 ± 12.6	79.3 ± 13.0	82.2 ± 10.7	NS
	Control	75.0 ± 15.0	74.7 ± 18.3	73.4 ± 18.1	72.5 ± 17.5
FEV1/FVC	Yoga	80.4 ± 11.5	82.6 ± 13.3	83.7 ± 13.4	83.1 ± 12.2	0.011
	Control	73.7 ± 14.9	74.8 ± 13.9	72.4 ± 15.1	73.3 ± 13.8
FEF 25–75%	Yoga	38.4 ± 14.6	42.0 ± 19.4	45.0 ± 20.5	45.0 ± 19.7	0.035
	Control	34.0 ± 18.3	33.8 ± 17.8	32.4 ± 18.1	31.1 ± 17.1

All values are % of predicted and expressed as mean ± SD.

* p < .05; † p < .01; ‡ p < .001 based on post-hoc pair wise comparisons with 0 wk values.

p-values were obtained from the between groups comparison in the GLM, NS – not significant

Category	Group	Week 0	Week 2	Week 4	Week 8	p -value
% fall in FEV1 with exercise challenge	Yoga (n = 29)	15.05 ± 14.0	8.81 ± 12.9	5.65 ± 12.9	5.18 ± 11.8	0.005
	Control (n = 28)	9.13 ± 10.8	9.50 ± 11.1	10.28 ± 10.9	5.81 ± 10.1	NS
ES subjects (≥ 15% fall in FEV1)	Yoga (n = 13)	26.71 ± 12.7	13.33 ± 16.1	9.90 ± 14.5	7.95 ± 15.1	0.003
	Control (n = 9)	21.47 ± 6.4	8.83 ± 9.8	18.69* ± 8.2	12.71 ± 9.1	0.015
ER subjects (<15% fall in FEV1)	Yoga (n = 16)	5.58 ± 5.1	5.13 ± 8.4	2.20 ± 10.6	2.93 ± 8.0	NS
	Control (n = 19)	3.29 ± 6.6	9.82 ± 11.9	6.31 ± 9.8	2.53 ± 9.0	NS

All values are expressed as mean ± SD. ES – exercise sensitive; ER – exercise resistant.

P-value was based on Friedman test applied on % fall in FEV1 after exercise challenge within each group separately.

* Between groups comparisons were made by Mann-Whitney U test at individual visits, there was significant difference observed at 4 wk between groups in exercise-sensitive subjects (p = 0.025).

Category	Group	Week 0	Week 2	Week 4	Week 8	p - value a
% change in 11β-PGF2α excretion. (All subjects)	Yoga (n = 29)	17.6 ± 18.6	19.7 ± 24.7	14.7 ± 16.5	16.8 ± 19.7	0.49
	Control (n = 28)	16.6 ± 21.0	18.6 ± 22.0	16.3 ± 22.3	20.7 ± 23.5	0.84
ES subjects (mean ± SD)	Yoga (n = 13)	18.3 ± 22.2	20.4 ± 29.5	13.8 ± 16.8	12.3 ± 16.9	0.63
	Control (n = 9)	15.5 ± 21.2	13.3 ± 18.1	28.5 ± 16.3*	18.9 ± 8.2	0.11
ER subjects (mean ± SD)	Yoga (n = 16)	17.1 ± 15.9	19.0 ± 21.0	15.4 ± 16.8	20.4 ± 21.5	0.79
	Control (n = 19)	17.0 ± 21.5	21.1 ± 23.6	10.6 ± 22.8	21.6 ± 28.2	0.08

All values (normalized) are expressed as % change in 11β prostaglandin F2α excretion with exercise challenge (mean ± SD). ES – exercise sensitive; ER – exercise resistant subjects.

^a P-value was based on Friedman test in each group separately from % change in 11β-PGF2α with exercise.

*p < .05 based on Mann-Whitney U test at 4 wk between two groups.

AQOL sub domains	Group	Week 0	Week 2	Week 4	Week 8	p -value
Symptoms	Yoga	3.77 ± 1.3	5.07 ± 1.4‡	5.38 ± 1.1‡	5.42 ± 1.2‡	0.033
	Control	3.63 ± 1.4	3.96 ± 1.7	4.42 ± 1.5†	4.70 ± 1.7†
Activity limitation	Yoga	3.66 ± 1.1	4.82 ± 1.3‡	5.21 ± 1.0‡	5.47 ± 1.1‡	0.033
	Control	3.67 ± 1.2	3.74 ± 1.5	3.90 ± 1.4	4.20 ± 1.5
Emotional function	Yoga	3.94 ± 1.5	5.10 ± 1.6†	5.45 ± 1.3‡	5.71 ± 1.3‡	0.006
	Control	3.60 ± 1.4	4.01 ± 1.6	4.15 ± 1.8	4.32 ± 1.7
Response to environmental stimuli	Yoga	3.46 ± 1.5	4.64 ± 1.5‡	5.0 ± 1.4‡	5.3 ± 1.6‡	NS
	Control	4.04 ± 1.4	3.83 ± 1.5	4.08 ± 1.6	4.40 ± 1.8
Total Quality of Life	Yoga	3.72 ± 1.2	4.93 ± 1.3‡	5.28 ± 1.0‡	5.46 ± 1.1‡	0.013
	Control	3.64 ± 1.1	3.90 ± 1.5	4.17 ± 1.4*	4.50 ± 1.5†

All values are expressed as mean ± SD.

* p < .05; † p < .01; ‡ p < .001 based on post-hoc pair wise comparisons with 0 wk values.

p-values were obtained from the between groups comparison in the GLM, NS – not significant.

There were no significant changes in pulmonary function indices in the control group during the course of the study. In contrast, there was a steady and progressive improvement in the subjects of yoga group during the same period. The change in the yoga group was statistically significant for FEV₁ at 8 wk and PEFR at 2, 4 and 8 wk, as compared to the corresponding baseline values (Table 3). In addition, significant group mean differences were observed between yoga and control groups over the 8-wk study period in PEFR, FEV₁, FEV₁/FVC and FEF_25–75%. In PEFR, since there is a significant baseline difference, baseline was considered as a constant covariate for between-group comparisons.

There was no significant change in serum ECP levels during the 8-wk study period in either group (Figures 1 and 2). The EIB decreased significantly in the yoga group, but not in the control group over the 8-wk study period (Table 4). Subgroup analysis in ES subjects revealed significant reduction in EIB over the 8-wk study period in both yoga and control groups but the amount of reduction observed was more marked in the yoga group than in the control group. In ER subjects the change in EIB was not significant in either group. Similar analysis of percentage change in urinary 11β-PGF2α levels in response to the exercise challenge revealed no significant change during the study in either group (Table 5). One interesting observation at 4-wk in the control group (in ES subjects) was that the EIB was rather significantly high, and this was associated with a significant increase in urinary 11β-PGF2α excretion in response to the exercise challenge as compared to the ES subjects in yoga group (Tables 4 and 5).

The AQOL scores showed an improvement over the 8-wk study period in both groups (Table 6). But the improvement was achieved relatively earlier and was more complete in the yoga group. At 2 wk, the improvement was statistically significant as compared to the baseline score in the total quality of life as well as each of the four sub-domains in the yoga group, but not in the control group. Even by 8-wk, significant improvement was seen in the control group only in total AQOL and symptoms but not in activity limitation, emotional function or the response to environmental stimuli. The NNT was found to be 1.82 for the total score, 2.41 for symptoms score, 1.66 for activity limitation score, 1.91 for emotional function score and 1.70 for the response to environmental stimuli score, which means ≤2 subjects needed to be treated with yoga plus conventional treatment for one subject to have a clinically meaningful improvement in quality of life over and above the improvement that the subject would have experienced with conventional treatment alone.

The frequency of rescue meditation use showed a significant decrease over the 8-wk study period in both the groups. But the decrease in rescue meditation use was achieved relatively earlier and was more marked in the yoga group than in the control group (Figure 3). Rescue medication use between yoga and control groups was significantly different at 2 and 4 wk because of the remarkable decrease in the frequency of the medication use only in the yoga group.

Although the level of compliance for yoga practice aimed at was at least 5 days a week, this level could not be sustained throughout the 8 weeks of the study. The compliance for yoga practice as reported by the subject was (average number of practice days per week): Wk 0, 4.6 ± 0.5; Wk 2, 4.6 ± 1.1; Wk 4, 4.5 ± 1.2; and Wk 8, 4.4 ± 1.1.

The present study has demonstrated that adding the mind body approach of yoga to the predominantly physical approach of conventional care results in measurable improvement in some subjective as well as objective outcomes in bronchial asthma. There have been previous RCTs on the efficacy of yoga which have arrived at similar conclusions[3, 6, 10]. But none of the previous trials have gone into the plausible mechanisms by which yoga might help bronchial asthma even in a small way as the present study has done. Since the major built-in difference between the two groups was the yogic intervention during 8-wk of the study, any difference in the outcome is likely to be due to yoga. The control being a wait-listed group, it does not control completely for non-specific effects of the experimental intervention such as expectation, belief, subject investment in time and effort, change in the subjects' daily routine, investigator interaction, social interaction and support, and placebo effect.

The 8-wk duration of the yogic intervention was an arbitrary compromise. It is long enough to demonstrate the effect, but the ideal would be a much longer study. However, in practice the decline in compliance increases steeply as the study gets longer, possibly owing to the time commitment required from the subjects[9]. Since there is no appropriate placebo possible for yoga, the subject cannot be blinded. The allocation of the subjects to the two groups was randomized, but the selection of subjects from the patient population was not random. Every subject who made it to our clinic to volunteer for the trial was already convinced in his mind about the beneficial effects of yoga because of its popularity in India. This is an inherent flaw of such trials, and limits the extrapolation of results to the entire subject population. However, this limitation does not reduce the external validity of the study because in practice only those subjects opt for a particular modality of treatment who have faith in its efficacy.

We chose, keeping the subjects' convenience and our infrastructure in mind, a 2-wk supervised out-patient intervention at IHC followed by 6 wk of closely monitored intervention at home. The 2-wk training period was adequate to make the subjects reasonably proficient in physical postures, breathing exercises, meditation and relaxation techniques, and to acquaint them with principles of stress management and a healthy yoga-based lifestyle. Leaving the subject to continue with these practices on his own and apply the principles learnt to everyday situations for 6 wk was reasonably long to test the feasibility of the intervention in real life, and to assess how far the gains achieved in 2 wk of supervised training were sustained during follow-up. Not only could the subjects continue with the intervention, the gains of the first 2-wk were improved upon during the 6-wk follow up.

The various interventions administered under the omnibus title 'yoga' cover a very wide spectrum. This is inevitable because yoga is not a system of medicine; it is a way of life, the implications of which go beyond health and disease[21]. When yoga is employed for prevention or management of disease, some convenient and highly visible elements of yoga are used selectively. Our intervention has used yoga as a tool in mind-body medicine[22]. This approach now has a strong scientific foundation in psychoneuroimmunology, and is particularly relevant to a disorder like bronchial asthma which is characterized by deranged immune function.

The results of the present study allow a few fairly firm conclusions. Significant, steady and progressive improvement in key objective variables such as PEFR and FEV₁ only in the yoga group but not in the control group indicates the efficacy of yoga. This is further substantiated by the significantly greater improvement in quality of life in the yoga group than in the control group.

In yoga group, there was also a significant trend towards improvement in exercise tolerance assessed by the exercise-induced fall in FEV₁, which became more evident in ES subjects. The effects of yoga on EIB in our study are similar to those reported by Jain et al. (1991)[5], who demonstrated a significant increase in exercise tolerance as indicated by a decrease in exercise-induced bronchial lability index (BLI) with yoga practice for 40-days in adolescents with mild to severe asthma and in another study by the same authors in moderate to severe chronic asthma patients[23].

Since the blood level of ECP is directly related to the severity of asthma and inversely related to lung functions, we have used ECP as a peripheral marker in understanding the disease progress [24, 25]. In our present study, no significant changes were observed in ECP in either group. The high variability in ECP levels suggests the need for a much larger number of subjects for arriving at definitive conclusions.

Apart from the IgE mediated mast cell activation[26], mast cells may also be activated independently of high affinity IgE receptor (FcεRI), by emotional stress and it can induce asthma exacerbations [27, 28]. The possibility is made more likely because psychological or emotional stress triggers dura mast cell secretion via release of corticotropin-releasing hormone, CRH[29]. Another study also indicated that acute psychological stress could lead to cardiac mast cell degranulation through CRH acting directly or through neurotensin[30]. Therefore, we speculated that yoga might play a vital role in reducing the mast cell activation levels by improving the emotional function of asthmatics thereby reducing the inflammatory condition and would cause the favourable effects on this outcome measure.

Another plausible explanation for the role of yoga in reducing the mast cell degranulation could be based on the frictional stress from air flowing through narrowed airways damaging the airway mucosa and thereby perpetuating airway inflammation and airway obstruction. At high air flow rates, high values of the frictional stress could damage the airway wall, especially during episodes of cough, and particularly when the mucosa is inflamed and friable as it is in asthmatic patients[31]. The slow and gentle breathing in some of the pranayamas (breathing practices in yoga) may reverse the process[32] by reducing the frictional stress, and thereby stabilizing the mast cell degranulation. Olness et al. (1999)[33] also demonstrated an inhibition of mast cell activation by conditioned relaxation techniques such as relaxation-imagery in children having migraine. In the present study, the urinary concentrations of 11β-PGF2α against exercise stimuli in yoga and control groups did not show any significant trend towards the inhibition of mast cell activation except a significant difference observed between groups at 4 wk in ES subjects (Table 5). Therefore, our study could not examine conclusively the above speculations because of high variability of 11β-PGF2α and a small sample size (yoga, 13; control, 9) in ES subjects. In addition, the exercise in the present study was a much less vigorous stimulus for provocation of airways and activating the mast cells than allergen provocation in which approximately 200–300% increase is seen in levels of urinary 11β-PGF2α with an allergen challenge[34].

The favourable effect of yoga in bronchial asthma observed by us in some outcome measures is consistent with similar results reported in several previous studies[3–5, 10]. Most of these, except the study by Jain et al (1991)[5], were also randomized controlled trials. But lately there have been a few studies which have reported either negative or very weak effects of yoga[6–9, 35]. All these were also controlled trials, and the study designs are apparently more rigorous than in the earlier trials. However, that does not necessarily mean that the positive results of earlier studies were due to insufficient rigor. Rather, it seems that in order to meet the exacting demands of methodology, some of the recent studies have overlooked some basic features of yoga. Moreover, yoga is much more than breathing exercises. It is only an integrated practice e.g. that given in the study by Nagarathna and Nagendra (1985)[10] or in the present study, which comes closest in an experimental situation to what yoga really is. In the study by Sabina et al (2005)[9], yoga has been equated with postures or breath work. The frequency is only twice a week without any serious monitoring of the frequency with which the practices are repeated at home on other days. Moreover, the control is a stretch. If yogic stretches are also treated like just a stretch, a non-yogic stretch could be equally good. It is only when the yogic stretch is performed with a yogic attitude, and preferably, when it becomes a component in the yogic way and view of life, that the yogic stretch acquires superiority over a non-yogic stretch[36]. That is possibly the reason why in the study by Sabina et al (2005)[9], both groups improved but the difference between the groups was not significant. In the most recent studies[8, 9], the scientific rigor has been improved upon by giving to the control group an intervention similar to that given to the yoga group, and the trials have been masked. Masking in a study which involves highly visible physical practices is meaningless. Further, if the interventions in the two groups are very similar, the outcomes in the two groups cannot be very different. The mere fact that in one group the techniques have been selected from a yogic text and in the other from a text on physiotherapy or modern psychology will not affect the outcome. Further, the comprehensive approach to yoga has been avoided probably to keep the intervention well-defined. But in the process of testing a holistic treatment using a design which is ideal for testing a drug, the holistic treatment should not be reduced to one of its components. For the sake of fitting our design into a rigid framework, we should not end up evaluating a modality of treatment which is different from the one we have set out to examine. That answers also one of the commonest criticisms leveraged at studies like the present one i.e. the study does not allow us to determine the proportionate contribution of each component of the intervention. To view a holistic treatment as a combination of components is convenient but inappropriate. The efficacy observed is that of the whole intervention, and may be greater than the sum of the efficacy of its components.

The present study is the first one to attempt an investigation into the mechanism by which yoga helps bronchial asthma. Although it has not succeeded in throwing much light in that direction, there are several other subtle reasons why this study and many more similar studies in the future would be justified. Although there are several studies available on the efficacy of yoga in bronchial asthma and several other diseases, studies have to reach a critical mass before they can influence practice. Further, in case of yoga, very few of the studies are randomized controlled trials[1]. Because of the dilution of a few RCTs by several less rigorous trials, and also because of widespread scepticism with which disciplines like yoga are approached by practitioners of conventional medicine, the impact of the RCTs is inadequate. Further, it would help to integrate mind-body approaches like yoga into the practice of scientific medicine if the trials not only show that these approaches work, but also how they work in terms of measurable basic mechanisms.

The present RCT has shown that adding a comprehensive yoga-based mind-body intervention to the conventional treatment improves several measures of pulmonary function in subjects having mild to moderate bronchial asthma. There is a significant trend suggesting a decrease in exercise-induced bronchoconstriction in the yoga group, particularly in the exercise-sensitive subjects. Yoga and control groups did not show a clear trend towards the inhibition of mast cell activation except for a significant difference observed between groups at 4 wk in exercise-sensitive subjects. Once again, in view of the high variability in response, a much larger number of exercise-sensitive subjects are required for definitive conclusions. Yoga improves the quality of life and reduces rescue medication use in bronchial asthma, and achieves the reduction earlier than conventional treatment alone. The trial supports the use of yoga in the management of bronchial asthma.