Effect of Short-Term Pranayama and Meditation on Cardiovascular Functions in Healthy Individuals

Abstract

Context:

Asana, pranayama, and meditation are three main techniques of yoga practiced in India over thousands of years to attain functional harmony between the body and mind. Recent studies on long-term yogic practices have shown improvements in cardiovascular functions.

Aim:

The present study was conducted to ascertain if a short-term practice of pranayama and meditation had improvements in cardiovascular functions in healthy individuals with respect to age, gender, and body mass index (BMI).

Settings and Design:

This interventional study was conducted in the Department of physiology of S.N. Medical College, Bagalkot.

Patients and Methods:

Fifty healthy subjects (24 males and 26 females) of 20–60 years age group, fulfilling the inclusion and exclusion criteria underwent two hours daily yoga program for 15 days taught by a certified yoga teacher. Pre and post yoga cardiovascular functions were assessed by recording pulse rate, systolic blood pressure, diastolic blood pressure, and mean blood pressure.

Statistical analysis used:

The parameters were analyzed by Student's t test.

Results:

There was significant reduction in resting pulse rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure after practicing pranayama and meditation for 15 days. The response was similar in both the genders, both the age groups, <40 yrs and >40 yrs and both the groups with BMI, <25 kg/m² and >25 kg/m².

Conclusion:

This study showed beneficial effects of short term (15 days) regular pranayama and meditation practice on cardiovascular functions irrespective of age, gender, and BMI in normal healthy individuals.

INTRODUCTION

Yoga is an ancient philosophical and religious tradition thought to have originated in India in 5000 BC. It has been incorporated into modern medicine during the few decades because of increasing incidence of diseases of modern civilization such as obesity, hypertension, coronary artery diseases, and diabetes mellitus, which are rooted in faulty lifestyle and psychological stress. Yoga is the best lifestyle modification, which aims to attain the unity of mind, body and spirit through asanas (exercise), pranayama (breathing), and meditation.[1]

Breath is a dynamic bridge between the body and mind.[2] Hence, life experiences can distort breathing pattern. Pranayama is the art of prolongation and control of breath helps in bringing conscious awareness to breathing and the reshaping of breathing habits and patterns .[2]

Meditation is a yogic process of providing deep rest to the system by allowing the mind to calm down to its basal states. It is often looked upon as a relaxation technique to be used for treating stress and stress-related illnesses.[3]

Different types of pranayama produce different physiological cardiovascular responses in normal young individuals. During right nostril pranayama and alternate nostril pranayama, the heart rate increased,[4] whereas during left nostril pranayama, there was a decrease[5] or no change in heart rate.[6] Four weeks of Nadisuddhi pranayama has shown significant decrease in pulse rate, diastolic blood pressure, systolic blood pressure along with significant increase in pulse pressure.[7] During ‘OM’ meditation, there was a significant reduction in heart rate as compared to the control period in which non-targeted thinking was encouraged.[8,9]

All these studies reported the effects of individual pranayama or meditation practice for minimum of 4 weeks to 6 months. Some studies also included the effects of asanas.

This study was carried out to know the physiological effects of short term (15 days) combined practice of pranayama and meditation in influencing cardiovascular status in healthy individuals of 20–60 years.

PATIENTS AND METHODS

The present study was conducted in the Department of Physiology. Ethical clearance for the study protocol was obtained from the Institute ethical committee.

Fifty healthy subjects of age group 20–60 years were selected randomly from a group of participants visiting the yoga center who had not yet started practicing yoga but were keen on learning. The same subjects were chosen as both study as well as control group in order to minimize the confounding factors and make the study more reproducible.

Subjects who were trained in yoga before, subjects with history of respiratory, cardiovascular and renal diseases, and diabetes were excluded from the study. Subjects who smoke and consume alcohol or any drugs were also excluded from the study. The subjects were selected after taking a detailed clinical history. An informed consent was obtained from all the members. Physical characteristics such as age, height, weight, and body mass index (BMI) were obtained. BMI was calculated as weight (kg) / height (m)². Pulse rate (PR) and blood pressure (BP) were recorded before practice of pranayama and meditation.

The subjects were asked to relax physically and mentally for 30 minutes in supine position in a silent room. In the same position, the pulse rate and the blood pressure were recorded. The pulse rate in beats per minute was recorded in the right radial artery by palpatory method for whole one minute. The systemic arterial blood pressure in millimeter of mercury (Hg) was recorded with a sphygmomanometer (Diamond), in the right upper limb by auscultatory method. Similarly, three readings of each subject's pulse rate and systemic blood pressure were taken at an interval of 15 minutes each and average of the three values calculated. The mean arterial (blood) pressure (MAP=DBP+1/3PP) was also calculated. All the parameters were recorded between 5 and 6 pm in order to avoid circadian variations.

All the subjects were under uniform dietary habits and received same yoga training for a period of 15 days for 2 hours daily between 6 and 8 pm. The subjects were instructed not to change their lifestyle or perform any other physical exercises during yoga training.

The yoga practice schedule consisted of

1. Prayer - 10 mins.

2. Pranayama - 45 mins.

3. Short break - 5 mins.

4. Lecture or film on fundamentals in nutrition, stress management, meditation and yogic attitude in daily life - 30 mins.

5. Meditation - 20 mins.

6. Prayer - 10 mins.

The different types of Pranayama[3] practiced were –

1. Vibhagiya Pranayama (sectional breathing)

   • Adama (Kanista) Vibhagiya Pranayama (diaphragmatic/abdominal breathing)
   • Madhyama Vibhagiya Pranayama (Thoracic/intercostal breathing)
   • Aadya (Jesta) Vibhagiya Pranayama (upper lobar/clavicular breathing)
   • Poorna mudra Pranayama (Full yogic breathing)

2. Nadishuddi Pranayama (Alternate nostril breathing)

3. Kapalabathi Kriya (cleansing breath)

4. Bahya Pranayama (the external breathing)

5. Cooling Pranayama

   • Sitali Pranayama
   • Sitkari Pranayama

The session was concluded by meditation[3] and prayer.

After 15 days, once again the cardiovascular status was assessed clinically in terms of PR and BP, as done before the start of pranayama and meditation training.

Results were presented as Mean SD. Student's t test was used to find the significance of study parameters by using SPSS 15.0 version. P value less than 0.05 was considered statistically significant.

RESULTS

The age of the subjects ranged from 20–60 yrs, the mean age being 38.60 ± 8.89 years. There were 6 subjects in the age group of 21–30 years, 23 subjects in the age group of 31–40 years, 17 subjects between 41–50 years, and 4 subjects between 51–60 years.

Out of the 50 subjects, 24 subjects were males and 26 were females. On analysis of the physical characteristics of the 50 subjects, the mean age (years) was 38.60 ± 8.89, the mean height (cm) was 159.38 ± 9.97, the mean weight (kg) was 64.21 ± 9.24 and the mean BMI (kg/m²) was 25.31 ± 3.29. Both the genders were age matched with significant variation in height (P < 0.001), weight (P=0.003), and BMI (P=0.025).

The mean resting pulse rate (beats/min), mean resting systolic, diastolic and mean arterial blood pressure (mm Hg) were reduced significantly after 15 days of yoga practice.

The results were also compared between two age groups- age ≤40 years (13 males, 16 females) and age >40 years (11 males, 10 females) and it was found that in both the age groups, there was a significant reduction in resting cardiovascular parameters after the yoga practice in both genders. When compared between two groups of BMI- BMI <25kg/m² and BMI>25kg/m², there was significant reduction in resting cardiovascular parameters after the yoga practice. The effect of 15 days pranayama and meditation practice on resting mean PR [Table 1], systolic blood pressure [Table 2], diastolic blood pressure [Table 3], and mean arterial blood pressure [Table 4] are represented in respective tables.

Table 1.

Effect of yoga on pulse rate (beats/min)

Table 2.

Effect of yoga on systolic blood pressure (mm of Hg)

Table 3.

Effect of yoga on diastolic blood pressure (mm of Hg)

Table 4.

Effect of yoga on mean arterial blood pressure (mm of Hg)

DISCUSSION

The significant decrease in resting pulse rate, systolic and diastolic blood pressure after the yoga practice in the present study is in accordance with the findings of other studies on physiological effects of yoga practice in healthy individuals.[10] Similar reduction in resting PR and blood pressure after yoga practice were also reported in hypertensive patients,[11,12] in asthmatic patients[13] and in diabetic patients.[14]

In the present study a highly significant reduction in PR, SBP, and DBP can be attributed to modulation of autonomic activity with parasympathetic predominance and relatively reduced sympathetic tone. This autonomic modulation in yoga is mediated through modification of breathing patterns which triggers various central and autonomic mechanisms as well as mechanical and hemodynamic adjustments causing both tonic and phasic changes in cardiovascular functioning.[15]

As a technique, pranayama can assume rather complex forms of breathing. But the essence of the practice is slow and deep breathing. Slow breathing induces a generalized decrease in the excitatory pathways regulating respiratory and cardiovascular systems. As respiratory and cardiovascular systems have similar control mechanisms, alteration in one system will modify the functioning of the other.[16] During slow and deep breathing lung inflates to the maximum. This stimulates pulmonary stretch receptors which bring about withdrawal of sympathetic tone in skeletal muscle blood vessels leading to widespread vasodilatation and decrease in peripheral resistance and thus decrease diastolic blood pressure.[7] While practicing pranayama one concentrates on the act of breathing which removes attention from worries and “de-stresses” him. This stress-free state of mind evokes relaxed responses in which parasympathetic nerve activity overrides sympathetic activity.[17]

Meditation by modifying the state of anxiety reduces stress-induced sympathetic over activity thereby decreasing arterial tone and peripheral resistance resulting in lowering of diastolic blood pressure and heart rate.[18] Regular practice of yoga has showed improvement in baroreflex sensitivity and decrease in the sympathetic tone thereby restoring blood pressure to normal level in patients of essential hypertension.[11,12]

In the present study, the responses to 15 days of regular combined practice of pranayama and meditation were also assessed with respect to age and gender. It revealed that both males and females responded similarly to the yoga practice.

When compared age wise, it revealed similar response to 15 days of pranayama and meditation practice in both age group ≤40 years and age group >40 years. In the present study, cardiovascular response in the age group >40 years is similar with the previous study.[10]

Although a significant decline in resting pulse rate, SBP, DBP, and mean arterial BP after the yoga practice in the present study is in accordance with the findings of other studies on physiological effects of yoga practice in healthy individuals, the present study has some differences. The present study involved regular combined practice of pranayama and meditation for 15 days, whereas other studies reported the effects of individual pranayama or meditation practice for minimum of 4 weeks to 6 months. Some studies also included the effects of asanas.

Most of the studies conducted so far have generalized their results irrespective of age and gender of the subjects. Very few studies have been conducted on subjects above 40 years in which age group, cardiovascular diseases are more prevalent. In the present study, an attempt was made to fill up these lacunae.

Although the present study observed the clear short term (15 days) effects of pranayama and meditation practice, it remains to be assessed whether these changes persist after resuming normal respiration and whether long term practice will lead to stable modifications of cardiovascular control.

Thus in a nutshell, with this study, it is proved beyond doubt, that regular practice of pranayama and meditation for minimum of 15 days is beneficial in improving the cardiovascular functions even in healthy individuals irrespective of age, gender, and BMI.

Finally, these results and their explanations would justify the incorporation of yoga as part of our lifestyle in promoting health and thereby preventing age related cardiovascular diseases.