Autonomic Functions in Raja-Yoga Meditators

396 Bharshankar, Mandape, Phatak, Bharshankar Indian J Physiol Pharmacol 2015; 59(4)

Original Article

Autonomic Functions In Raja-yoga Meditators

Jyotsana. R. Bharshankar1*, Archana D. Mandape1,Mrunal S. Phatak1, Rajay N. Bharshankar2

1Department of Physiology,Indira Gandhi Government Medical College,Nagpur

2Department of Physiology,AIIMS, Bhopal

Abstract

Stress, an inevitable and constant feature throughout the lifetime, induces autonomic dysfunctions, for whichmeditation is considered to be an antidote. So the case control study was planned including 50 Raja-yogameditators practicing meditation for 5 years and 50 age matched non-meditators. Autonomic function testswere performed and results were compared using the Student- t test. Mean values of resting HR, SBP andDBP were less in meditators. Galvanic Skin Response in meditators was significantly more (p<0.001). Meanincrease BP response to Hand Grip Test and Cold Pressor Test was significantly less in meditators thannon-meditators (p<0.001). Standing: Lying ratio, Valsalva ratio, Inspiration: Expiration ratio and 30:15 ratioswere significantly increased in meditators than non-meditators. From the results, there was shifting of theautonomic balance to parasympathetic side in Raja-yoga meditators, which suggests its utility to combatthe ill effects of stress.

Indian J Physiol Pharmacol 2015; 59(4) : 396–401

*Corresponding author :

Dr. Jyotsana. R. Bharshankar, Associate Professor,Department of Physiology, Indira Gandhi GovernmentMedical College, Nagpur – 440018 (Maharashtra) India;Email : [email protected]

(Received on Nov. 15, 2014)

temporary relief. Yoga and meditation are one of thenon pharmacological approaches to relieve stressand strain on long term basis (1, 2).

Meditation is considered as an antidote to the mindsvulnerabi l i ty to tox ic emot ions. Research onmeditation has mostly focussed on changes thatoccur during the period of meditation compared witha resting condition (3, 4). All types of meditationclaim to change everyday behaviour and the benefitsof it are not restricted to the period of meditationpractice (1).

Most of the studies on meditation have dealt withtranscendental meditation, zen meditation and tantricyoga (4, 5). Raja yoga meditation is practiced widely

Introduction

With the advent of modernization and mechanizationtoday’s human being is subjected to far greaterstress, strain and depression than before. As a resultof which, it has taken toll on us by giving rise tovarious psychosomatic disorders. The remedialmedicines used for these disorders are giving

Indian J Physiol Pharmacol 2015; 59(4) Autonomic Functions and Raja-Yoga 397

Anthropometric parameters like height and weightwere measured. Body mass index (BMI) wascalculated by the formula weight in Kg/height in metersquared. For assessment of autonomic functions allthe participants were given appointment at 10 am inthe physiology department. The investigations werecarried out under similar conditions and by the sameperson. Resting blood pressure (BP) was recordedwith the help of sphygmomanometer in the left armin sitting (relaxed) position by auscultatory method.Three readings were taken at the time interval of 15minutes and average was taken as the final reading.Resting heart rate was obtained from ECG recordedwith the help of 16 channel computerised polygraph(PHYSIOPAC pp-4, Medicaid system, Chandigarh,India).

Autonomic assessment was done with the battery oftests for sympathetic functions and for parasympatheticfunctions (8).

Sympathetic function tests

1. Galvanic skin resistance (GSR): It was recordedusing two silver chloride disc electrodes filledwith electrode jelly placed at 4 cm apart onpalmer surface of right hand. GSR values weresampled continuously at 20 sec interval (3). Thevalue after one minute was noted which wascalculated automatically by the computerisedpolygraph.

2. Handgrip test (HG): The participant was askedto hold the handgrip dynamometer (Medicaidsystem, Chandigarh) in the dominant hand andpress it with maximum effort. The tensiondeveloped was measured. The procedure wasrepeated three times and the average was takenwhich was the maximum isometric tension(Tmax).Then the subject was asked to maintain30% of the Tmax for 3-5 minutes. BP wasrecorded from the non exercising arm every 30sec before the release of handgrip. Maximumincrease in BP before the release of handgripwas noted (9).

3. Cold pressor test (CP): It was done as one ofthe last test because of its unpleasantness. The

in India and has centres all over the world. It definesmeditation as the highest state of consciousness inwhich the mind is fully relaxed even when the physicalbody is engaged in day to day work (6). Thistechnique requires considerable commitment andinvolves concentrated thinking (3). The present studywas designed to observe the effect of long term RajaYoga meditation, on the autonomic functions.

Methods

The protocol for the case control study was approvedby the Institutional Ethics committee. Hundredvolunteers of either sex, between the age 25 to 45years were selected. They were divided into 2 groups,meditators and non-meditators. The meditators were50 in number, practising Raja yoga meditation everymorning (7:30 am - 8:30 am) for more than 5 years,at the local Bramhakumari centre situated in Mahal,Nagpur. It was their daily practice and was underthe guidance and supervision of the senior meditators.The Raja yoga Meditation was practiced in comfortablesitting posture with eyes open and gaze fixed on ameaningful symbol (light). At the same time theywere actively thinking positive thoughts about auniversal force pervading all over as light and peace(7).

The non-meditators were selected randomly from thenon teaching staff of the Indira Gandhi GovernmentMedical College, Nagpur who had never done anykind of meditation. All the volunteers were havingsimilar dietary habits and working conditions.

After detail history and clinical examination thosewho were smokers, alcoholics, or suffering from anyrespiratory disease, hypertension, congenital orischemic heart disease, chronic renal fai lure,diabetes, liver disease or taking medicine likely toalter the autonomic functions were excluded fromthe study. The object ives of the study wereexplained to the participants and their writteninformed consent was obtained. Equal numbersof men and women participants were included ineach group. Menstrual history was taken for allwomen and they were investigated in their proliferativephase.


participant was asked to immerse his hand for 1minute in cold water maintained at 4-6oC and BPwas measured from the other arm at the end of1 minute (10, 11, 12).

Parasympathetic function tests:

1. Standing: lying ratio (S/L ratio): The participantwas asked to stand quietly and then lie downwithout any support. Continuous electrocardiogram(ECG) was recorded in lead II from 20 beatsbefore and 60 beats after lying down with thehelp of computerised polygraph. A mark wasmade to indicate the point at which the subjectstarted to lie down. The individual RR intervalswere measured from the ECG and the resultsexpressed as (9).

−=−

Standing lying ratiolongest R R interval during 5 beats before lying down

:shortest R R interval during 10 beats after lying down

2. 30:15 Ratio: The participant was asked to liesupine for 15 min. Then he was asked to standup and remain motionless for 1 to 3 minutes.Continuous ECG was recorded in lead II. Theratio was calculated as (9).

−=

−longest R R interval 30 beats after standing

30 :15shortest R R interval 15 beats after standing

ratio

3. Valsalva ratio (VR): The participant was informedto sit comfortably. Then he was asked to blowout in the rubber tube of mercury manometer (40mm test) and maintain the pressure of 40 mmHgfor 15 seconds. A continuous ECG was recordedone min before the strain, during the strain and45 seconds following the strain release. Valsalvaratio was calculated as (9).

−=

−longest R R interval after the strain

shortest R R interval during during the strainValsalva ratio

4. Expiration: Inspiration ratio (E/I ratio): In thesitting position, the participant was asked tobreathe deeply at the rate of 6 breaths/minallowing 5 sec each for inspiration and expiration.

Continuous ECG was recorded during this periodand the ratio was calculated as (9).

−=

−longest R R interval during expiration

:shortest R R interval during inspiration

Expiration Inspiration ratio

Statistical methods:

The data was analysed to obtain the arithmetic meanfor age, height, weight, BMI, systolic and diastolicBP, heart rate, GSR, S/L ratio, 30:15 ratio, valsalvaratio and E/I ratio. Difference in the mean valueswas subjected to students-t test. Sample size wascalculated using the formula for difference of means.Power of the study was 80% and significance levelwas set as p<0.05.

Results

Medi tators and non-medi tators d id not showstatistically significant difference in the mean valuesof physical characteristics such as age, height,weight and BMI as shown in Table I.

The mean values of resting cardiovascular parameterslike heart rate (p<0.01), systolic blood pressure(p<0.01) and diastolic blood pressure (p<0.05) weresignificantly less in meditators than in non meditatorsas shown in Table II.

Sympathetic system assessment showed significantincrease in GSR in meditators than non-meditators(p<0.001). The blood pressure response to handgriptest showed less rise in systolic BP in meditatorsthan in non-meditators with p<0.001. Diastolic blood

TABLE I : Physical characteristics of meditators and non-meditators.

Non-meditators) Meditators Z PParameters (n=50 (n=50 value value

(Mean±SD) (Mean±SD)

Age (years) 35.82±5.21 37.42±5.58 1.48 > 0.05Ht (meters) 1.57±0.06 1.55±0.06 0.67 > 0.05Wt (kg) 56.34±9.12 55.44±8.64 0.10 > 0.05BMI (kg/m²) 22.98±3.66 22.07±2.36 0.38 > 0.05

p>0.05 non significant, Ht: Height, Wt: Weight, BMI: Bodymass index.


Discussion

Resting cardiovascular parameters

The values for resting HR, SBP and DBP weresignificantly lower in Raja-yoga meditators. This couldbe because dominance of parasympathetic oversympathetic system in meditators. The findings ofour study are similar to those by other researchers(2, 3, 13-15).

Meditation by reducing the anxiety levels minimizesthe sympathetic hyperactivity induced by stress.Decreased sympathetic activity causes decrease inthe catecholamine secretion which leads to peripheralvasodi latat ion and improvement in per ipheralcirculation (15) resulting in decrease in DBP. Regularyogic practices also reduces basal metabolic rateand resting oxygen consumption (16). All thesefactors decrease work load on the heart leading todecrease in heart rate leading to decreased cardiacoutput and hence the systolic blood pressure.

Sympathetic Functions

The GSR was significantly increased in meditatorsthan in non-meditators (P<0.001). Other studies alsoshowed similar results (3, 4, 19, 18). Decrease inskin resistance is a sign of increased sympathetictone (9). Thus the significant increase in GSR inmeditators observed in present study as comparedto non-meditators support the explanation that thesympathetic activation in meditators in response tostress was lesser due to changes attributed to headganglion of autonomic nervous system by regularpractice of meditation.

pressure response to handgrip was also statisticallysignif icant with less r ise in BP in meditators(p<0.001). Blood pressure response to cold pressertest was also significantly less in meditators thannon-meditators for SBP (p<0.05) and for DBP(p<0.001) Table III.

Assessment of parasympathetic system showed thatS/L ratio, valsalva ratio & E/I ratio were significantlyhigher in meditators than non-meditators (P<0.001).The 30:15 ratio also showed significant increase inmeditators than non–meditators (p<0.01) as shownin Table IV.

TABLE II : Mean values of resting cardiovascular parametersin meditators and non-meditators.



Resting HR 81.28±7.19 77.55±6.58 2.71 < 0.01(bpm)

Systolic BP 111.36±13.28 105.64±8.27 2.59 < 0.01(mmHg)

Diastolic BP 73.96±8.09 70.36±6.92 2.39 < 0.05(mmHg)

p<0.05: significant, p<0.01: highly significant, p<0.001:very highly significant.

TABLE III : Mean va lues o f sympathe t i c parameters inmeditators & non meditators.



GSR (kΩ) 314.62±161.75 881.88±370.98 9.91 < 0.001

Rise in SBP 23.48±11.87 17.08±5.19 3.49 < 0.001during HGT(mmHg)

Rise in DBP 21.56±6.99 16.2±4.80 4.47 < 0.001during HGT(mmHg)

Rise in SBP 16.84±7.45 13.88±5 2.33 < 0.05during CPT(mmHg)

Rise in DBP 13.04±4.35 10.32±2.59 3.80 < 0.001during CPT(mmHg)

p<0.05: significant, p<0.01: highly significant, p<0.001:very highly significant, GSR: galvanic skin resistance,SBP: systo l ic b lood pressure, DBP: d iasto l ic b loodpressure, HGT-handgrip test, CPT-cold pressor test.

TABLE IV : Mean values of parasympathetic parameters inmeditators and non-meditators.



S/L ratio 1.07±0.11 1.19±0.15 4.56 < 0.00130:15 ratio 1.12±0.11 1.18±0.08 3.12 < 0.01valsalva ratio 1.14±0.14 1.33±0.24 4.84 < 0.001E/I ratio 1.27±0.17 1.41±0.18 4.00 < 0.001

p<0.05: significant, p<0.01: highly significant, p<0.001:very highly significant, S/L: standing/lying, E/I: expiration/inspiration.


The results of Handgrip test are in accordance withthe studies (21, 20, 16). Results of cold presser testcan be compared wi th the f ind ings of otherresearchers (2, 22). Under conditions of stress ofeither physical or psychological origin, there isactivation of sympathetic nervous system. The coldpresser response which consists of placing hand inice cold water acts as a painful stimulus (23).Handgrip exercise is also characterised by increasein blood pressure and heart rate. (24) Meditationcauses decreased sympathetic activity and increasedvagal tone, these may be possible reasons for lessincrease in BP in meditators with HG and CP test.

Parasympathetic parameters

The increase in S/L, 30:15, VR and E/I ratio inmeditators indicates increase parasympatheticactivity in meditators than non-meditators. The

findings of our study are matching with other studies(2, 14, 20, 25). Increased parasympathetic activity(20) and Increased baroreceptor sensitivity (26)were attributed as possible mechanisms for theimprovement of parasympathetic parameters inmeditators by these researchers.

Thus from our study we can conclude that there isa better balance between the sympathetic andparasympathetic components of the autonomicnervous system in persons practising Raja yogameditation daily for at least one hour for minimum 5years. These changes might help an individual tocombat stress in household and working environmentand thereby reducing the related morbidity due topsychosomatic disorders. The simple and easy topractice method of meditation should be looked asan effective intervention and not merely a spiritualgesture or a relaxation technique.

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Autonomic Functions in Raja-Yoga Meditators

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