|Year : 2019 | Volume
| Issue : 4 | Page : 316-323
Effects of Yoga on cardiorespiratory profile of young adult indian male participants residing in West Bengal: A cross-sectional study
Rajarshi Ray1, Arunima Chaudhuri2, Debasis Adhya1, Abhijit Biswas1, Samarjit Koner1
1 Department of Physiology, Burdwan Medical College and Hospital, Bardhaman, West Bengal, India
2 Department of Physiology, Rampurhat Government Medical College and Hospital, Rampurhat, West Bengal, India
|Date of Submission||30-Oct-2018|
|Date of Acceptance||16-Jan-2019|
|Date of Web Publication||8-Jul-2019|
Krishnasayar South, Borehat, Burdwan - 713 102, West Bengal
Source of Support: None, Conflict of Interest: None
Background: Stress-related diseases are becoming the number one killer in the modern age. Aims: The aim of the study is to identify the effects of yoga on cardiorespiratory profile and stress levels of young adult Indian males residing in West Bengal. Materials and Methods: This cross-sectional pilot project was conducted after taking institutional ethical clearance and informed consent of the participants. Hundred healthy young adult Indian males in the age group of 18–30 years performing yoga regularly were selected as study population, and hundred age- and sex-matched participants from local population not performing any type of yoga were selected as control. Life event stress and perceived stress scores of the participants were measured using presumptive life event stress scale and perceived stress scale (PSS), respectively. Fasting blood sugar (FBS) and lipid profile were analyzed. Anthropometric measurements, resting pulse rate, blood pressure, electrocardiogram, and pulmonary function test were recorded. Unpaired t-test was used to analyze the data. Results: Weight, waist–hip ratio, and body mass index were significantly raised in participants not practicing yoga. Resting pulse rate, systolic blood pressure, and diastolic blood pressure were significantly lower in participants practicing yoga. PSS scores were significantly less in participants practicing yoga. FBS, total cholesterol, triglyceride, and low-density lipoprotein level in serum were significantly lower in participants practicing yoga, and high-density lipoprotein value was significantly raised. Duration of QRS complex, P-R interval, Q-T interval, and R-R interval were significantly raised in participants practicing yoga. The amplitude of T-wave and amplitude of S-T segment were significantly lowered in participants practicing yoga. Forced expiratory volume in 1 s and forced vital capacity values were found to be significantly raised in participants practicing yoga. Conclusions: Perceived stress adversely affects cardiovascular and respiratory profile of healthy young adult males, and regular practice of yoga may decrease perceived stress levels and help in modulating cardiorespiratory profile.
Keywords: Cardiovascular profile, perceived stress, respiratory profile, yoga
|How to cite this article:|
Ray R, Chaudhuri A, Adhya D, Biswas A, Koner S. Effects of Yoga on cardiorespiratory profile of young adult indian male participants residing in West Bengal: A cross-sectional study. Med J DY Patil Vidyapeeth 2019;12:316-23
|How to cite this URL:|
Ray R, Chaudhuri A, Adhya D, Biswas A, Koner S. Effects of Yoga on cardiorespiratory profile of young adult indian male participants residing in West Bengal: A cross-sectional study. Med J DY Patil Vidyapeeth [serial online] 2019 [cited 2019 Sep 18];12:316-23. Available from: http://www.mjdrdypv.org/text.asp?2019/12/4/316/262227
| Introduction|| |
Stress is defined as a state of threatened homeostasis, and homeostasis is reestablished by complex behavioral and physiologic adaptive responses. Modern man no longer faces the epidemic of plague, but stress-related diseases are becoming the number one killer. Negative thoughts and attitudes are at the root of these diseases. In the process of coping with challenges and running in emergence, our body functions undergo adaptive changes which shift set point of hypothalamic-pituitary axis toward sympathetic dominance. The result is immediate rise of heart rate, blood pressure, temperature, respiratory rate, and plasma catecholamine and corticosteroid levels. World population is adapting unhealthy habits and lifestyles, which may lead to emergence of wide variety of diseases such as coronary heart disease (CHD), hypertension, and diabetes mellitus. CHD is more common in individuals subjected to chronic stress, and recent research has focused to identify and prevent this growing problem, particularly with respect to stress at workplace. CHD is one of the leading causes of morbidity and mortality worldwide. WHO report in 2011 estimated 23.6 million deaths due to cardiovascular diseases (CVD) by the year 2030. Young males suffer more from CVD as compared to females of the same age group. Hormonal factors are thought to play an important role in this regard. Testosterone raises low-density lipoprotein cholesterol (LDL-C) and decreases plasma high-density lipoprotein cholesterol (HDL-C) which in turn is a major risk factor for atherogenesis. The cardiac vagotonic and sympatholytic effects of estrogen can explain, at least in part, why premenopausal women compared with postmenopausal women have a lower CHD incidence and mortality rate. Acute myocardial infarction (MI) is accompanied by decreased heart rate variability (HRV), which is due to reduced vagal or increased sympathetic outflow to the heart. Estrogen is a sympathoinhibitor and vagotonic hormone. A metabolite of progesterone exerts sympathoinhibitory effect and attenuates sympathetic baroreflex responses through central mechanism.
Previous studies have shown that perceived stress negatively affects cardiovascular functions by altering cardiovascular reactivity and increasing blood pressure. The autonomic dysfunction induced by chronic stress can explain at least in part the cause of this association., Stress causes increased cortisol secretion and increased sympathetic activity. However, it remains less clear whether there is any relation between stress-induced cortisol secretion, change in autonomic activity, and fat distribution among healthy nondepressed people.,
Yoga, a 3000-year-old tradition, is now regarded as a complementary and alternative medicine (CAM) in the western world. Yoga is mind–body technique which involves relaxation, meditation, and a set of physical exercises performed with synchronized breathing. Yoga benefits mental and physical health by modulation of hypothalamic–pituitary–adrenal axis and sympathetic nervous system (SNS) outflow.
Yogic practices enhance muscular strength and body flexibility, promote and improve respiratory and cardiovascular function, promote recovery from and treatment of addiction, reduce stress, anxiety, depression, and chronic pain, improve sleep patterns, and enhance overall well-being and quality of life.,
Yoga encourages one to relax, slow the breath, and focus on the present, shifting the balance from the SNS and the flight-or-fight response to the parasympathetic system and the relaxation response; thus, it lowers breathing and heart rate, decreases blood pressure, lowers cortisol levels, and increases blood flow to the intestines and vital organs. Many studies show that yoga lowers the resting heart rate, increases endurance, and can improve the maximum uptake and utilization of oxygen during exercise.
The present study was conducted to identify the effects of yoga on cardiorespiratory profile and stress levels of young adult Indian males residing in West Bengal so that early lifestyle modifications may be advised to improve the quality of life.
It is a cross-sectional study; authors should mention it in the title and in the places where it is necessary.
This study is cross-sectional and may not be contributing to any new research findings in yoga research, and parameters tested are already proven by many studies done in India and abroad, but a study in a population of West Bengal with yoga protocol followed by Government of India on the occasion of “International Yoga Day” 2016 may contribute some positive results.
| Materials and Methods|| |
This cross-sectional pilot project was conducted in the Department of Physiology, Burdwan Medical College and a few yoga centers in Kolkata and Burdwan from May 2016 to April 2017 after taking institutional ethical clearance (Memo BMC/PG/4418, dated 11 December 2015) and informed consent of the participants. This was a cross-sectional study, thus having its own limitations.
Hundred highly stressed young adult Indian males in the age group of 18–30 years performing yoga regularly (at least for 6 months) were selected as study population, and hundred age- and sex-matched participants from local population not performing any type of yoga were selected as controls.
All participants included in the study had PSLES score >200 as they had higher risk of developing disease.
Participants suffering from chronic debilitating diseases such as CHD, hypertension, diabetes mellitus, nephropathy, respiratory diseases, neuropathy, bleeding disorders, malignancy smokers and alcoholics, persons receiving any drugs that may affect the autonomic reflexes, and participants on any daily exercise regime other than yoga were excluded from the study. Females were not included in the present study as premenopausal females are at lesser risk of developing CVD.
Sample size was calculated with Epi info 6 software with α = 0.05 and β = 0.2 considering previous studies. On the first appointment, history was carefully recorded followed by clinical examination. Life event stress and perceived stress of the participants were measured using presumptive life event stress scale and perceived stress scale (PSS), respectively.,
Sampling was performed using multistage and random cluster method. The first stage of sampling included a simple random sample to select five institutions with male yoga practitioners from Burdwan and Kolkata. In the second stage of sampling, thirty participants were randomly selected from each institution, who were then administered questionnaires. For selection of the control group, five hundred participants were randomly chosen following the exclusion and inclusion criteria from areas adjacent to the yoga centers. All participants were on nonvegetarian diet, and their dietary habits were nearly similar. Age and body mass index (BMI) on the 1st day of admission were already available in the database of yoga centers where they were practicing, and there was no significant difference in both parameters with the control group in our study with P > 0.05.
Yoga protocol was taken from the common yoga protocol followed by the Government of India on the occasion of “International Yoga Day” 2016. It included warm-up exercises, Asanas, and Pranayama. At the time of recruitment, participants were taught and then supervised yogic exercises on one-to-one basis by the certified yoga instructor. The participants followed this regimen for 1 h every day for 5 days in a week. The protocol is given in [Table 1].
|Table 1: Yoga protocol followed by the Government of India on the occasion of “International Yoga Day” 2016.|
Click here to view
Presumptive life event stress scale
The stress level of the participants was assessed according to presumptive life event stress scale. Accordingly, they were categorized into no stress, less/moderate stress, and severe stress. Score stress up to 40: no stress; 41–200: less/moderate stress; and >200: severe stress.
Finally, 100 male participants from the yoga centers with scores above 200 were selected as the study group and 100 male participants not practicing yoga with PSLES scores >200 as controls, as they had a higher risk of developing illness. There was no significant difference in age and PSLES scores between participants of both groups. Dietary habits and lifestyles of both groups were comparable. Among the whole population administered with PSLES, not a single participant had PSLES score <40. Among participants practicing yoga, 58% had PSLES score >200 and 42% <200 but >40. Similarly, in participants not practicing yoga, 55% had PSLES score >200 and 45% <200 but >40.
The PSS of Sheldon Cohen, the most widely used psychological instrument for measuring the perception of stress, was used. It is a measure of the degree to which situations in one's life are appraised to be stressful. The questions in the PSS ask about feelings and thoughts during the last month. It comprises ten items, four of which are reverse scored, measured on a five-point scale from 0 to 4. PSS scores are obtained by reversing responses (e.g., 0 = 4, 1 = 3, 2 = 2, 3 = 1, and 4 = 0) to the four positively stated items (items 4, 5, 7, and 8) and then summing across all scale items. Total score ranges from 0 to 40.
Pretest instructions were given to avoid consumption of any drugs that may alter the cardiorespiratory parameters 48 h before the test. The participants were advised to have light dinner within 8 p. m. and go to bed early and avoid stressful situations during the day before the tests were conducted. Relaxing bedtime routine, such as soaking in a hot bath or hot tub and then reading a book or listening to soothing music, was advised. They were asked to avoid caffeine (e.g., coffee, tea, soft drinks, and chocolate), nicotine (e.g., cigarettes and tobacco products), and alcohol close to bedtime. On the day of the test, no cigarette, nicotine, coffee, or drugs were permitted. Informed consent was obtained from the participants. All these protocols were used as an additional precautionary measure to decrease perceived stress in participants which may alter test results in spite of recruitment of participants following exclusion criteria.
Fasting blood samples were drawn from participants for analysis of fasting blood sugar (FBS) and lipid profile.
ECG was recorded and lead II was used to calculate various parameters.
A long lead II was recorded for at least 10–5 s. If the rhythms were regular, i.e., successive RR intervals were fairly constant, 1500/RR in mm was considered as a reasonably accurate value of HR. However, when there was variation in RR interval, the number of RR intervals that were contained in the 10 s strip was taken and multiplied by six. Pulmonary function tests (PFTs) were analyzed by computerized spirometry: Helios 401. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1:FVC ratio were taken as parameters of PFT.
The computer software “the Statistical Package for the Social Sciences (SPSS) version 16 (SPSS Inc., released 2007, SPSS for Windows, version 16.0. SPSS Inc., Chicago, Illinois, USA)” was used to analyze the data, and unpaired t-test was used. The data were considered significant and highly significant if the analyzed probability values (P values) were <0.05* and P < 0.01**, respectively.
| Results|| |
In the present study, 200 young adult Indian male participants within the age group of 18–30 years without any gross systemic disease were selected. They were divided into two groups on the basis of practicing yoga for at least 6 months, each group containing 100 participants. The group practicing Hatha yoga was named as participants practicing yoga and another not practicing the same as participants not practicing yoga. Both the groups were age matched, sex matched, and height matched, and they were all on nonvegetarian diet. Weight, waist–hip ratio, and BMI were significantly raised in participants not practicing yoga, in comparison to participants practicing yoga [Table 2]. Resting pulse rate, systolic blood pressure, and diastolic blood pressure were significantly lower in participants practicing yoga [Table 3]. PSS scores were significantly less in participants practicing yoga [Table 4]. FBS, total cholesterol, triglyceride, and LDL level in serum were significantly lower in participants practicing yoga than participants not practicing yoga, and HDL value was significantly raised in participants practicing yoga than participants not practicing yoga. Very LDL (VLDL) value shows no significant difference between these two groups [Table 5]. Duration of QRS complex, P-R interval, Q-T interval, and R-R interval were significantly raised in participants practicing yoga in comparison to participants not practicing yoga. The amplitude of T-wave and amplitude of S-T segment were significantly lowered in participants practicing yoga as compared to participants not practicing yoga [Table 6]. FEV1 and FVC values were found to be significantly raised in participants practicing yoga in comparison to participants not practicing yoga, but FEV1:FVC ratio did not show any significant difference between these two groups [Table 7].
|Table 2: The average values of age, weight, height, body mass index, waist-hip ratio of the two groups|
Click here to view
|Table 3: The average values of pulse, systolic blood pressure, and diastolic blood pressure ratio of the two groups|
Click here to view
|Table 4: The average values Cohen perceived stress scale and presumptive life event stress scale of the two groups|
Click here to view
|Table 5: The average values of fasting blood sugar, cholesterol, triglyceride, low-density lipoprotein, high-density lipoprotein, and very low-density lipoprotein of the two groups|
Click here to view
|Table 7: The average values of forced expiratory volume in 1 s, forced vital capacity, and forced expiratory volume in 1 s: forced vital capacity ratio of the two groups|
Click here to view
| Discussion|| |
The present study was conducted to observe the effect of stress and yoga on cardiorespiratory parameters, FBS, and lipid profile of young adult Indian male participants. Yoga is now regarded in the Western world as a holistic approach to health and is classified by the National Institutes of Health as a form of CAM  to combat with the stressful life and its adverse effect. This is a cross-sectional study and has got its own limitations. In the present study, PSS scores were significantly lower in yoga practitioners, and there was no difference in PSLES scores between both groups. Satyapriya et al. studied the effect of integrated yoga practice and guided yogic relaxation on both perceived stress and measured autonomic response in healthy pregnant women. Participants were randomized for practicing yoga and deep relaxation or standard prenatal exercises 1 h daily. Perceived stress decreased by 31.57% in the yoga group and increased by 6.60% in the control group. They concluded that yoga practice reduces perceived stress and improves adaptive autonomic response to stress in healthy pregnant women.
The distribution of body fat in different position of our body has significant effect in various health issues, mainly the central obesity, i.e., abdominal subcutaneous fat is strongly responsible for morbidity than subcutaneous fat in any other site of our body., Evidence from longitudinal studies suggests that chronic life stress may be causally linked to weight gain. Stress-induced overeating may be one reason contributing to the development of obesity which increases the risk of CVD. Jääskeläinen et al. in 2014 showed that compared with nonstress-driven eaters, stress-driven eaters had a higher prevalence of overweight, obesity, and abdominal obesity. Torres and Nowson  found that perceived stress was positively correlated with BMI and waist–hip ratio. The present study also showed significantly higher values of weight, BMI, and waist/hip ratio in participants not practicing yoga, compared to participants practicing yoga and these parameters were positively correlated with perceived stress levels.
Mean values of pulse rate, SBP, and DBP in the present study were significantly raised in participants not practicing yoga, compared to participants practicing yoga. Yoga can affect cardiac autonomic regulation with increased HRV and vagal dominance during yoga practices. Regular yoga practitioners were also found to have increased vagal tone at rest compared to non-yoga practitioners. It is premature to draw any firm conclusions about yoga and HRV as most studies were of poor quality, with small sample sizes and insufficient reporting of study design and statistical methods. Rigorous studies with detailed reporting of yoga practices and any corresponding changes in respiration are required to determine the effect of yoga on HRV. Similar results were noticed by Gujjala and Aruna Kumari, 2014. Sukhsohale and Phatak, 2012, in their studies showed significant decrease in systolic blood pressure in meditators which is more decreased with increase in the duration of the meditation. Shilpa et al. in 2011 showed that in meditators, heart rate, systolic blood pressure, and diastolic blood pressure were significantly low as compared to nonmeditators. Similar results were also observed by Wang et al. in 2013 and Hagins et al. in 2013.
India has more diabetics than any other country in the world, according to the International Diabetes Foundation. According to recent estimates, approximately 51 million people had diabetes in 2010, and by 2030, 87 million people are expected to have diabetes in India. Keeping in view the alarming increase in the incidence and prevalence of diabetics in India, the WHO has declared India as the Diabetic Capital of the World.
The mean values of FBS in participants not practicing yoga group were significantly higher compared to participants practicing yoga group in the present study. Chaya et al. reported significant decrease in fasting plasma insulin in the yoga practitioners. They also found that long-term yoga practice (for 1 year or more) is associated with increased insulin sensitivity and attenuation of the negative relationship between body weight or waist circumference and insulin sensitivity. Manjunatha et al. studied the effect of four sets of asanas in random order for 5 consecutive days and observed that the performance of asanas led to increased sensitivity of B-cells of the pancreas to the glucose signal.
By the year 2015, cardiovascular mortality is likely to rise to 90% in females in India. High-circulating serum cholesterol, LDL-C, and serum triglycerides are major risk factors of this disease.,
In the present study, cholesterol, triglyceride, and LDL levels were significantly lower and HDL levels were significantly higher in participants practicing yoga as compared to participants not practicing yoga, but no difference in VLDL levels was observed.
Schmidt et al. found that there was significant reduction in cardiovascular risk factors after 3 months of residential yoga and meditation training program that included low fat lactovegetarian diet. BMI, total cholesterol and LDL, fibrinogen, and blood pressure were significantly reduced, especially in the participants with elevated levels. Mahajan et al. demonstrated that participants with known ischemic heart disease as well as healthy participants practicing yoga showed a regular decrease in all lipid parameters except HDL. Vyas and Dikshit in 2002 cited in their article that serum lipid profile showed a significant lowering of serum cholesterol in short- and long-term meditators as compared to nonmeditators. Lipid profile of short- and long-term meditators was better than the profile of nonmeditators in spite of similar physical activity.
In the present study, there was no significant difference in mean values of amplitude of P-wave between the two groups, but amplitude of ST segment and T-wave was significantly less in participants practicing yoga. Duration of P-R interval, QRS complex, Q-T interval, and R-R interval were significantly more in participants practicing yoga.
In a study published in 2016 influence of short-term practice of yoga for the duration of 1 month in healthy male volunteers was observed. Demonstrable change in HRV, with a significant decrease in sympathetic activity and trend toward an increase in parasympathetic activity was studied thereby demonstrating sympathovagal balance toward parasympathetic predominance.
Heart rate or pulse rate is a great tool for monitoring the effects of training on the cardiovascular system in real time. We examined R-R interval to interpret cardiac vagal tone in these two groups, and from the study, it is obvious that participants practicing regular yoga have increased parasympathetic activity, which makes their R-R interval significantly longer than participants not practicing yoga.
In the present study, FVC and FEV1 values were significantly higher in participants practicing yoga, but no difference in FVC: FEV1 was observed. A study  reported that yoga postures, breath control, and relaxation techniques taught to 287 college students (89 men and 198 women) in two 50-min class meetings for 15 weeks significantly improved FVC. Karmur et al. in 2015 conducted a study on 40 participants (30 males and 10 females). Various PFTs were measured. It was aimed to find effects of 10 weeks' yoga practice on some PFTs. FVC, FEV1, peak expiratory flow rate and maximum expiratory pressure were found to be increased in all participants after the 10 weeks of yoga practice.
A gross discrepancy in the values of amplitude of P-wave, T-wave, and ST segment may be observed in the present study. Similar results have also been observed in previous studies. The electrocardiographic response pattern during exercise at low and high heart rate was compared with the response pattern during emotional stress in a study by Hijzen and Slangen in 1995. Qualitative differences between exercise and emotional stress were obtained, i.e., during exercise, the ST segment was more depressed, T-wave amplitudes were larger, and QT and PQ were significantly shorter than during emotional stress. The results did not support the suggestion that emotional stress evokes an exercise-like cardiovascular response pattern, which may lead to a metabolically maladaptive situation. The results were in accordance with the hypothesis that the electrocardiogram (ECG) changes during emotional stress are similar to the ECG changes during right stellate stimulation, while the ECG changes during exercise are similar to the ECG changes obtained during left stellate stimulation.
The left and right stellate ganglia provide the majority of the sympathetic innervation to the heart through postganglionic fibers although the left stellate ganglion is quantitatively dominant at the ventricular level. MI may lead to partial denervation of these fibers at the level of the myocardium and paradoxically induce a supersensitivity to catecholamines, making the heart more vulnerable to the electrical induction of ventricular arrhythmias. Sympathetic denervation counteracts this pathologic process by reducing the amount of norepinephrine released at the ventricular level and increasing the ventricular fibrillatory threshold. Coronary vasodilation and vagal stimulation to the heart are also increased. The QT interval is regulated by cardiac sympathetic innervation; shortening of the QT interval occurs with the left stellate ganglion block whereas lengthening of the QT interval occurs with the right stellate ganglion block.,, In the present study, there was significant lengthening of QT interval following yoga training. This is similar to the findings of Hijzen and Slangen. Their study demonstrated that the ECG changes during emotional stress were similar to the ECG changes during right stellate stimulation, and significant lengthening of QT interval following yoga training in the present study may be due to modulation of cardiovascular responses following training.
Limitations and future scope
There is a need for an objective marker of improvement in research evaluating the beneficial effects of stress management programs. Salivary immunoglobulin A, salivary amylase, dehydroepiandrosterone, catecholamines, cytokines, and the other glucocorticoids are few of the physiological mediators that work with Cortisol. Measurement of these parameters may contribute to a more comprehensive understanding of the body's response to stress and to interventions designed to reduce stress when coupled with self-report data.
| Conclusions|| |
Perceived stress adversely affects cardiovascular and respiratory profile of healthy young adult males, and regular practice of yoga may decrease perceived stress levels and help in modulating cardiorespiratory profile with decreasing future complications such as diabetes, dyslipidemia, coronary artery disease, and metabolic syndrome.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Lucini D, Norbiato G, Clerici M, Pagani M. Hemodynamic and autonomic adjustments to real life stress conditions in humans. Hypertension 2002;39:184-8.
Lau HL, Kwong JS, Yeung F, Chau PH, Woo J. Yoga for secondary prevention of coronary heart disease. Cochrane Database Syst Rev 2012;12:CD009506.
Chaudhuri A, Ray M, Saldana D, Bandopadhyay AK. Cardio-respiratory response of young adult Indian male subjects to stress: Effects of progressive muscle relaxation. Med J Dr D Y Patil Univ 2014;7:1-6.
Tanaka M, Sato M, Umehara S, Nishikawa T. Influence of menstrual cycle on baroreflex control of heart rate: Comparison with male volunteers. Am J Physiol Regul Integr Comp Physiol 2003;285:R1091-7.
Allen MT, Bocek CM, Burch AE. Gender differences and the relationships of perceived background stress and psychological distress with cardiovascular responses to laboratory stressors. Int J Psychophysiol 2011;81:209-17.
Suter PM, Maire R, Holtz D, Vetter W. Relationship between self-perceived stress and blood pressure. J Hum Hypertens 1997;11:171-6.
Ross A, Thomas S. The health benefits of yoga and exercise: A review of comparison studies. J Altern Complement Med 2010;16:3-12.
Bharshankar JR, Bharshankar RN, Deshpande VN, Kaore SB, Gosavi GB. Effect of yoga on cardiovascular system in subjects above 40 years. Indian J Physiol Pharmacol 2003;47:202-6.
Desikachar K, Bragdon L, Bossart C. The yoga of healing: Exploring yoga's holistic model for health and well-being. Int J Yoga Ther 2005;15:17-39.
Harinath K, Malhotra AS, Pal K, Prasad R, Kumar R, Kain TC, et al.
Effects of Hatha Yoga and Omkar meditation on cardiorespiratory performance, psychologic profile, and melatonin secretion. J Altern Complement Med 2004;10:261-8.
Mannapur B, Dorle AS, Hiremath LD, Ghattargi CH, Ramadurg U, Kulkarni KR. A study of psycological stress in undergraduate medical students at S. N. Medical College, Bagalkot, Karnataka. J Clin Diagn Res 2010;4:2869-74.
Cohen S, Kamarck T, Mermelstein R. A global measure of perceived stress. J Health Soc Behav 1983;24:38596.
Williams K, Steinberg L, Petronis J. Therapeutic application of Iyengar Yoga for healing chronic low back pain. Int J Yoga Ther 2003;13:55-67.
Satyapriya M, Nagendra HR, Nagarathna R, Padmalatha V. Effect of integrated yoga on stress and heart rate variability in pregnant women. Int J Gynaecol Obstet 2009;104:218-22.
Pouliot MC, Després JP, Lemieux S, Moorjani S, Bouchard C, Tremblay A, et al.
Waist circumference and abdominal sagittal diameter: Best simple anthropometric indexes of abdominal visceral adipose tissue accumulation and related cardiovascular risk in men and women. Am J Cardiol 1994;73:460-8.
Torres SJ, Nowson CA. Relationship between stress, eating behavior, and obesity. Nutrition 2007;23:887-94.
Jääskeläinen A, Nevanperä N, Remes J, Rahkonen F, Järvelin MR, Laitinen J, et al.
Stress-related eating, obesity and associated behavioural traits in adolescents: A prospective population-based cohort study. BMC Public Health 2014;14:321.
Tyagi A, Cohen M. Yoga and heart rate variability: A comprehensive review of the literature Int J Yoga. 2016;9:97-113.
Gujjala R, Aruna Kumari D. Meditation: A stress reliever. J Evol Med Dent Sci 2014;3:7008-13.
Sukhsohale ND, Phatak MS. Effect of short-term and long-term Brahmakumaris Raja Yoga meditation on physiological variables. Indian J Physiol Pharmacol 2012;56:388-92.
Shilpa D, Kanyakumari K, Raj PN. Effect of anapanasati meditation on cardiovascular parameters and lipid profile. Indian J Physiol Pharmacol 2011;55:370-77.
Wang J, Xiong X, Liu W. Yoga for essential hypertension: A systematic review. PLoS One 2013;8:e76357.
Hagins M, States R, Selfe T, Innes K. Effectiveness of yoga for hypertension: Systematic review and meta-analysis. Evid Based Complement Alternat Med 2013;2013:649836.
Ramachnadaran S. Insight into the Mechanism of Primary Prevention of Type 2 Diabetes: Improvement in Insulin Sensitivity and Beta cell Function. Genetic and Epigenetic Basis of Complex Diseases. Conference in Centre for Cellular and Molecular Biology; 2009.
Gupta V. Diabetes in elderly patients. JK Pract 2002;91:258-9.
Chaya MS, Ramakrishnan G, Shastry S, Kishore RP, Nagendra H, Nagarathna R, et al.
Insulin sensitivity and cardiac autonomic function in young male practitioners of yoga. Natl Med J India 2008;21:217-21.
Manjunatha S, Vempati RP, Ghosh D, Bijlani RL. An investigation into the acute and long-term effects of selected yogic postures on fasting and postprandial glycemia and insulinemia in healthy young subjects. Indian J Physiol Pharmacol 2005;49:319-24.
Das S, Yadav D, Narang R, Das N. Interrelationship between lipid peroxidation, ascorbic acid and superoxide dismutase in coronary artery disease. Curr Sci 2002;83:488-91.
Mahajan AS, Reddy KS, Sachdeva U. Lipid profile of coronary risk subjects following yogic lifestyle intervention. Indian Heart J 1999;51:37-40.
Schmidt T, Wijga A, Von Zur Mühlen A, Brabant G, Wagner TO. Changes in cardiovascular risk factors and hormones during a comprehensive residential three month kriya yoga training and vegetarian nutrition. Acta Physiol Scand Suppl 1997;640:158-62.
Vyas R, Dikshit N. Effect of meditation on respiratory system, cardiovascular system and lipid profile. Indian J Physiol Pharmacol 2002;46:487-91.
Vinay AV, Venkatesh D, Ambarish V. Impact of short-term practice of yoga on heart rate variability. Int J Yoga 2016;9:62-6.
] [Full text]
Birkel DA, Edgren L. Hatha yoga: Improved vital capacity of college students. Altern Ther Health Med 2000;6:55-63.
Karmur KA, Joshi VS, Padalia MS, Sarvaiya JL. Effect of ten weeks yoga practice on pulmonary function tests. Int J Biomed Adv Res 2015;6:682-5.
Hijzen TH, Slangen JL. The electrocardiogram during emotional and physical stress. Int J Psychophysiol 1985;2:273-9.
Zipes DP, Mihalick MJ, Robbins GT. Effects of selective vagal and stellate ganglion stimulation of atrial refractoriness. Cardiovasc Res 1974;8:647-55.
Egawa H, Okuda Y, Kitajima T, Minami J. Assessment of QT interval and QT dispersion following stellate ganglion block using computerized measurements. Reg Anesth Pain Med 2001;26:539-44.
Schwartz PJ. Cardiac sympathetic denervation to prevent life-threatening arrhythmias. Nat Rev Cardiol 2014;11:346-53.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]