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ORIGINAL ARTICLE
Year : 2023 | Volume
: 9
| Issue : 1 | Page : 53-59
Role of yoga in prehypertension and hypertension
Anil Kumar1, G Keshavamurthy2, Navreet Singh3, Balwinder Singh4, Rajesh Vaidya5, Tanmoy Roy6, SP Singh7, Ankush Gupta4, Nitin Bajaj8, Parag Barwad9, Ekambir Singh10
1 Consultant Medicine and Cardiologist, Deputy Principal Medical Officer, Western Air Command, New Delhi, India
2 Consultant Medicine and Cardiologist, Department of Cardiology, Army Hospital (Research & Referral), Dhaula Kuan, New Delhi, India, New Delhi
3 Consultant Medicine and Cardiologist, AICTS, Golibar Maidan, Pune, Maharashtra, India
4 Classified Specialist Medicine and Cardiologist, AICTS, Golibar Maidan, Pune, Maharashtra, India
5 Dean, Armed Forces Medical College, Pune, Maharashtra, India
6 Principal Medical Officer, Western Air Command, New Delhi, India
7 Prof of Physiology, Department of Physiology, Army College of Medical Sciences, Brar Square, Near Base Hospital Delhi Cantt, New Delhi, India
8 Senior Adviser Medicine and Cardiologist, Department of Cardiology, AICTS, Golibar Maidan, Pune, Maharashtra, India
9 Department of Cardiology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
10 Institute of Medical Sciences and SUM Hosptial, Kalinganagar, Bhubneshwar, Odisha, India
Correspondence Address:
Navreet Singh
AICTS, Golibar Maidan, Pune - 411 040, Maharashtra
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jpcs.jpcs_39_22
Background: The high prevalence of hypertension in India necessitates both pharmacological and nonpharmacological measures to control it. Here, we report the findings of a study to investigate the effectiveness of yoga therapy in lowering blood pressure (BP) in prehypertensive and hypertensive individuals. Methods: This was a single center, nonrandomized controlled clinical trial, of 200 hypertensives and 100 prehypertensives patients. The control group received the prescribed antihypertensive and lifestyle modification while the yoga group was additionally taught simple yogic exercise by a trained yoga teacher. This training included intensive supervised phase 2-h training sessions in Ujjayi breathing, Bhastrika Pranayama and chanting of “Om” for 10 lessons, followed by self-performed yogic exercise at home for 1 h till the end of study at 1 year. Results: The systolic BP (SBP) in the hypertensive yoga group was significantly lower (t = 3.04, P < 0.01) than the control group at 6 months, but not so at 1 year (SBP t = 0.53, P > 0.05). In the prehypertensive participants, at 6 months (t = 5.85, P = 0.00), and 1 year (t = 6.385, P < 0.05) a significant difference was observed between SBP of the two groups However, no significant difference was observed between the diastolic BP among hypertensives or prehypertensives at 6 months and 1 year. Conclusion: Our present study indicates that yoga therapy is a viable adjunct to pharmacological intervention to reduce SBP in the management of hypertension and prehypertension and that yoga should be incorporated in the treatment regime of such patients, specifically for individuals who have prehypertension.
Keywords: Hypertension, pre-hypertension, yoga
The prevalence of hypertension in India is approximately 30.7%, with over 230 million adults over the age of 18 years affected by it. It is estimated that around 17.6% of all hypertensives globally, live in India. The prevalence in young adults (20–40 years) is especially high and more than twice the prevalence in a similar population in the United States (22.4% vs. 10.5%, respectively).[1] This increased prevalence of hypertension and prehypertension among young Indians is being increasingly reported and is a disturbing trend because it puts an increasing number at risk for cardiovascular diseases (CVDs) related to hypertension.
Delayed detection, inadequate treatment, nonavailability of drugs, and poor drug compliance compound the morbidity and mortality associated with this disease. Nonpharmaceutical measures such as exercise, weight reduction to ideal limits, low salt diet, meditation, and yoga have been found to be effective in lowering blood pressure (BP). These measures can be used independently or as adjuvants to drug therapy to maintain a sustained reduction in BP.[2]
The meaning of “Yoga” is “union” in Sanskrit and involves rhythmic breathing to create a union of breath control, posture, and meditation. Each of these components is addressed by various “asanas” to have a comprehensive and collective benefit. A large number of studies demonstrate the changes in sympathovagal balance, favorable to CVD, with the practice of yoga.[2]
Here, we report the findings of a study planned to investigate the effectiveness of yoga therapy, in lowering BP in prehypertensive and hypertensive individuals. This is probably the first study to assess this effect in prehypertensive patients and to compare it with hypertensive patients.
MethodsStudy design
This was a single-center, nonrandomized case − control clinical trial.
Classification of blood pressure
The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High BP (JNC VII) has been referred to define elevated BP as below (in mmHg):
Normal: <120 mmHg and <80 mmHgPrehypertension: 120–139 mmHg and 80–89 mmHgStage I Hypertension: 140–159 mmHg and 90–99 mmHgHypertension Stage II: >160 mmHg and >100 mmHg.At the initial presentation in the clinic, BP measurements were made using the standard protocol mentioned in the JNC VII. Thereafter, the patients were divided into hypertensive and prehypertensives.
Twenty-four hour ambulatory BP monitoring is more accurate in measuring the average BP and hence was the modality used of BP monitoring thereafter.
Inclusion criteria
Age older than 18 yearsPrehypertension or hypertension Stage 1 and 2No target organ damage: Stroke, acute coronary syndrome, and renal failureNo comorbid states such as coronary artery disease, diabetes, acute or chronic renal failure, and peripheral arterial disease.Exclusion criteria
Accelerated hypertensionTarget organ damage as abovePresence of comorbidity as abovePhysical or mental incapacity to perform yogaSystolic BP (SBP) <120 mmHg.Sample size and participants
The sample size was calculated using the standard normal variate for 5% error and 80% power with a drop-out rate of 10%, and assuming a mean treatment difference of 5 mmHg in the SBP between the yoga group and control group. This assumption in BP difference was made based on a meta-analysis of 17 studies.[2]
Two hundred adult patients with hypertension and 100 adults with prehypertension were enrolled in the study on diagnosis. Anti-hypertensive drugs were optimized in first 02 months and not increased thereafter till the end of the study. If office BP under standard measurement techniques was not controlled to <159/99 mmHg at 02 months, a drug increase was performed, and the patient was excluded from the study. Any patient requiring increase in drug therapy after inclusion was also excluded from the study. The Consort Flow Diagram for Hypertensives and Prehypertensives is shown in [Flow Chart 1] and [Flow Chart 2] respectively.
Lifestyle modifications were advised as per Dietary Approach to Stop Hypertension (”DASH”) regimen to all participants of the study.
Randomization and intervention
Although randomized controlled trials (RCTs) are the gold standard to provide unbiased data, when patients have treatment preference, randomization may influence participation and outcomes. During the interviews for the inclusion of participants (for prehypertension) and patients (hypertensives), a few already had been doing yoga, and randomization of them to the control group would have entailed them stopping their regime. Hence, randomization was not done.
All patients with prehypertension and hypertension were divided into either of two groups-control group or yoga group. All patients and participants were explained the study protocol and were free to choose any group based on their acceptance of the adherence to the formulated yoga exercise regime. Patients were added to either group until the desired number was reached.
The first group (control) continued to receive the prescribed antihypertensive and lifestyle modification as advised.
The second group (Yoga group) was prescribed medication, lifestyle modifications and additionally were taught simple yogic exercise by a trained Yoga teacher.
Yoga regime
This training included intensive supervised phase 2-h training sessions for 02 weeks (10 lessons) followed by self-performed yogic exercise until the end of the study (1 year). At home the participants practiced the yogic exercises for at least 1 h.
Yogic exercise involved mainly breathing exercises performed in a cool (20°C–25°C) well ventilated room. They were as follows:
Ujjayi breathing, which is a slow consciously regulated breathing technique against a contracting glottis (”resistance breathing”) at various rates and inspiratory/expiratory ratios. It is known to increase cardiovagal baroreflex sensitivity and is a prelude to further yogic exercises[3]Bhastrika pranayama in Vajrasana or Sukhasana involves deep breathing through the nostrils with an inspiratory/expiratory sequence of up to 4/6 s without using the abdominal muscles. The subject was asked not to focus on the breathing pattern but think of vast open meadows and skies.[4] followed byChanting “OM” in the Sukhasan position, which involves breathing through both nostrils and exhaling using the sequential combination of “A, U (O) and M,” thus producing the sound of a female humming beeThe correct posture for the exercises was repeatedly reinforced, especially involving the axial skeletal system.Follow-up
All participants (controls and yoga group) were contacted every 2 weeks to determine their BP control, drug compliance, lifestyle measures, and adherence to yoga exercises. The adherence was checked by direct questioning, on telephone and when the participant visited the outpatient department. In the yoga group, the three mandatory asanas and their correct method were reinforced.
Outcome measures
SBP and diastolic BP (DBP) were the outcome of interest.
Data analysis
The two groups were compared, i.e., the yoga group and the control group, for differences in mean changes from baseline using a linear regression model (Analysis of covariance) using the Statistical Analysis System Version 9.2 Suit (100 SAS Campus Drive Cary, NC 27513-2414, USA). BP was taken as a continuous variable. To determine whether yoga therapy was more effective in the treatment of hypertension, the mean difference in the SBP of the yoga and control group and DBP of the yoga and control, respectively, was analyzed by an intension to treat. All comparisons were made by the two-sided t-test.
ResultsA total of 200 hypertensives and 100 prehypertensives were studied.
Among hypertensive medications, the age range of the patients was 25–65 years with a mean age of 49.3 years. One hundred and forty-nine (75%) were male patients and 51 (20%) patients were diabetic. Among prehypertensive participants, the age range of patients was 25-65 years with a mean age of 47.1 years. Seventy-nine (79%) were men and 13 (13%) patients were diabetic.
The number of respondents reporting for the follow-up was progressively lower. In hypertensive patients at 6 months, there were 96 in the yoga group and 88 controls (yoga group/control group), and at 1 year, the remaining sample was 84 and 79, respectively. In the prehypertensive participants, there were 43/38 (yoga group/control group), and at 1 year, it was 39/34, respectively.
The reasons for exclusion during the study are tabulated in [Table 1] and the baseline characteristics in all patients and participants in [Table 2].
Table 2: The baseline characteristics of all the patients and participantsThe mean SBP and DBP recordings at entry, 06 months and at 1 year for the hypertensives is as shown in [Table 3] and for the prehypertensives in [Table 4]. At the beginning of the study, there was no significant difference in SBP and DBP between the two comparative groups among hypertensives and prehypertensives.
Table 3: Significance of difference between the mean systolic blood pressure and diastolic blood pressure in hypertensives between yoga group and control group at entry, 6 months and 1 year
Table 4: Significance of difference between the mean systolic blood pressure and diastolic blood pressure in prehypertensives between yoga group and control group at entry, 6 months and 1 yearThe SBP and DBP in the yoga and control groups among the hypertensives were lower than the entry level in the two follow-up sessions at 6 months and 1 year. SBP in the hypertensive yoga group was significantly lower (t = 3.04, P < 0.01) than in the control group. However, no significant difference was observed between the DBP of the two groups (t = 1.70, P > 0.05). At 1 year also, SBP and DBP were lower in the yoga group but were not statistically significant (SBP t = 0.53, P > 0.05; DBP t = 0.98, P > 0.05).
In prehypertensive participants at the start of the study, there was no significant difference between SBP and DBP in the yoga group and the control groups (t = 1.19, P = 0.23). At 6 months (t = 5.85, P = 0.00), and 1 year (t = 6.385, P < 0.05) significant difference was observed between SBP of the two groups However, the DBP difference was not statistically different between the two groups at 6 months and 1 year (t = 0.4, P = 0.44 and t = 1.62, P = 0.1).
Of the control group, 12 patients progressed to hypertension, although stage 1 only and required treatment, while only two patients in the yoga group progressed to stage 1 hypertension and required treatment.
DiscussionThe present study was carried out to study the effects of yoga on BP in patients with hypertension and prehypertension.
In hypertensive patients at 6 months of follow-up, there was a reduction in SBP and DBP in both the yoga group and the control group. This marked reduction in SBP in both the yoga and control groups at 6 months was likely due to the emphasis on all lifestyle measures such as exercise, the DASH diet, and drug compliance.
At 6 months, on comparing the two groups, the SBP was significantly lower (t = 3.04, P < 0.03), in the yoga group compared to the controls at 6 months, indicating a major BP lowering effect of yogic exercises.
At 1 year also, SBP and DBP were lower in the yoga group but were not statistically significant (SBP t = 0.53, P > 0.05; DBP t = 0.98, P > 0.05). This indicates that the beneficial effect of yoga, although present, had plateaued. This could be due to BP in both groups reaching lower levels due to improved sympatho-vagal balance, without affecting the other putative mechanisms, such as the renin-angiotensin mechanism.[1],[3]
Although the decrease was not statistically significant, the trend toward a lower value could be due to the additive effect of yogic exercises to the other pharmacological and nonpharmacological measures. Adherence to medication and “dietary discipline” was relatively high in both groups, suggesting that lifestyle advice provided to the control arm during educational sessions may have attenuated the observed effects of the intervention.[3],[5] This mitigating effect of nonyogic measures on primary outcomes was also observed by Prabhakaran et al. In the YoGa trial, although this trial was on rehabilitation after acute myocardial infarction.[6]
No significant differences were found between the DBP of two groups at initial entry (P = 0.58), 6 months (P = 0.07), and 1 year (P = 0.18), indicating that the beneficial effect of yoga therapy was restricted to SBP. Murugesan et al. also noted that yoga significantly reduced the SBP but did not reduce the DBP.[7]
Poor compliance with the yogic exercise regime and self-reduction of antihypertensive medication was also considered in the yoga group, but considering regular feedback and reaffirmation of the protocol, this is less likely.[2]
It is postulated that although the reduction in BP is not statistically significant, the overall benefit in the reduction of cardiovascular risk over time is likely to be substantial, because it is known that a 10-mmHg decrease in SBP led to a 13% reduction in all-cause mortality, independent of the initial mean SBP.[2],[8],[9]
In prehypertensive participants, the SBP was significantly lower in the yoga group at 6 months (t = 5.85, P = 0.00) and 1 year (t = 6.38, P = 0.00), indicating that yoga therapy was beneficial even for longer duration. This sustained effect could be because prehypertensives compared to hypertensives had less pathology, such as arteriosclerosis, making them more amenable to an intervention. This effect could also be due to the self-discipline enthused by yoga, which could have made participants more focused on other measures such as weight loss, healthy eating habits, and regular exercise.
However, as in the hypertensive group, no significant differences were found between the mean DBP of the two groups at 6 months (t = 0.04, P > 0.44) and 1 year (t = 1.62, P > 0.1) reaffirming the observation that the peripheral vascular tone is not significantly affected by yoga. SBP and DBP depend upon stroke volume, arterial elastance and compliance and the total peripheral arterial resistance. The SBP is more dependent on stroke volume and compliance, while the DBP is more dependent on peripheral arterial resistance. It is likely that the vagomimetic effect of Yoga is more sustained than the sympatholytic effect. This could result in a relative increase in venous capacitance and arterial compliance, thus decreasing SBP. However, as the sympatholytic response is low, which determines the peripheral resistance, the DBP remains insignificantly unchanged.[10],[11]
Potential Mechanisms: The word yoga is derived from the Sanskrit word “yug” which means union of mind, body and spirit.[12] The core objectives of our protocol were to provide a structured program of yogic exercises to optimize physical and psychosocial function, thereby improve health behaviour. Synchronized exercise of breathing movements, stretching, and meditation have a direct and indirect benefit on vascular and mental health.[5],[13],[14],[15] This is mainly caused by stimulation of the parasympathetic nervous system, through greater sensitivity of baroreceptors that lead to improvements in heart rate variability and increase in arterial and venous capacitance. There is a simultaneous (though modest), reduction of sympathetic overactivity and dominance with decrease in the distal peripheral resistance and vascular tone, thus further reducing the BP and pulse rate.[13],[15]
In a meta-analysis of 17 studies to analyze the effectiveness of yoga in reducing BP in adults with hypertension, Hagins et al. observed that yoga had a modest but significant effect on SBP and DBP. They further demonstrated that only yoga incorporating all the three basic elements of yoga practice, namely, posture, meditation and breathing brought about this reduction. Though they observed that the studies reviewed were marred with bias, they recommended yoga as an effective intervention for reducing BP.[2] Tyagi and Cohen. also is a large systematic review of RCTs, nonrandomised trials and cohort studies involving 6693 subjects found that yoga effectively reduced the BP in normotensive and hypertensive subjects.[16] In a metanalysis of RCTs from 2010 to 2021 Khandekar et al. inferred that in addition to hypertension, yoga also shows a significant reduction in SBP and DBP in prehypertensive populations and therefore can be recommended in the prehypertensive population. This could have a beneficial effect in reducing the chances of developing hypertension or CVD.[17]
Quality of life and subjective well-being are positively augmented in patients who regularly practice yoga, which reduces mental stress, further reducing BP.[4],[18],[19] Stress reduction has positive feedback on the hypothalamic-pituitary neuroendocrine axis, reducing the release of cortisol and renin and their downstream vascular and endocrine effects.[20] Yoga is also believed to enhance serotonergic and decrease dopaminergic activity to positively affect mood, self-motivation, and self-efficacy through psychosocial pathways, thus motivating the individual to lead a healthier life.[4],[21]
It would be worthwhile to mention that since lowering SBP is more strongly associated with prevention of all-cause mortality, cardiovascular mortality, major cardiovascular events, coronary heart disease, stroke, heart failure, and end-stage renal disease than DBP, the additive effect of yoga in lowering SBP is likely to have a significant effect on the longevity of patients.[22]
Limitation of the study
The primary limitation of the study was that it was a nonrandomized study. There was also no objective measure of adherence to correct yogic postures, which could have been done by video conferencing. Furthermore, while the 'meditation' component of yoga was discussed, it could have been taught in more detail. Other lifestyle measures undertaken by the participants on their own were also not measured and included in the study.
Our present study indicates that yoga therapy is a viable adjunct to the pharmacological intervention for the management of hypertension and prehypertension.
Together, the present results implicate an advantage of incorporation of yoga therapy into the treatment regime of hypertensives and prehypertensives, specifically for individuals who are at the initial stage, i.e., prehypertensive, where pharmacological treatment is not recommended.
Recommendations
Ujjayi breathing, Bhastrika Pranayama in Vajrasana followed by, “OM” chanting in Sukhasan position, performed for 1 h/day should be prescribed to hypertensive and prehypertensive individuals to significantly reduce SBP.
Ethics clearance
The principles in the Declaration of Helsinki on ethical issues in medical research were followed. Informed consent was taken, and the study was approved by the Local Ethical Review Board.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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