Effect of Meditation on Respiratory System, Cardiovascular System and Lipid Profile
RASHMI VYAS* AND NIRUPAMA DIKSHIT
Department of Physiology,
B. J. Medical College,
Ahmedabad – 380 016
*Corresponding Author and present address:
Department of Physiology, Christian Medical College and civil
(Received on July 16, 2001)

 

Abstract: In this study, respiratory functions, cardiovascular parameters and lipid profile of those practicing Raja Yoga meditation (short and long term meditators) were compared with those of nonmeditators. Vital capacity, tidal volume and breath holding were significantly higher in short and long term meditators than nonmeditators. Long term meditators has significantly higher vital capacity and expiratory pressure than short and long term meditators than nonmeditators. Long term meditators had significantly higher vital capacity and expiratory pressure than short term meditators. Diastolic blood pressure was significantly lower in both short and long term meditators as compared to nonmeditators. Heart rate was significantly lower in long term meditators than in short term meditators and nonmeditators. 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 inspite of similar physical activity. This shows the Raja Yoga meditation provides significant improvements in respiratory functions, cardiovascular parameters and lipid profile.

 

Key words:     meditation                     raja yoga                      lipid profile      

cardiovascular parameters                                 respiratory functions

Introduction
Methods
Results
Discussion
References

 

INTRODUCTION

METHODS

The study was conducted on 105 human volunteers of either sex divided into three groups-non meditators, short term meditators (meditating for 6 months to 5 years) and long-term meditators (meditating for more than five years). The non-meditators were a mixed group of students and staff of B. J. Medical College and Civil Hospital, Ahmedabad who had never done any kind of meditation. The meditators were practicing Raja Yoga meditation for 1 hour every morning (7.30 A.M. – 8.30 .M.) at the local Brahmakumari Centre, Ahmedabad. In Raja Yoga meditation the individual uses visual or auditory images for concentration which helps one to proceed to meditation.

Details of age, sex, smoking, intake of alcohol, physical exercise undertaken if any, dietary habits (whether vegetarian or non vegetarian) are given in Table I. All measurements except heart rate were performed in the local Brahmakumari center on meditators and in the Physiology department, B. J. Medical College, Ahmedabad on the non-meditators. Heart rate was inferred from E.C.G. taken in the E.C.G. laboratory for all the subjects. All observations were made between 8:30 A.M. and 9:30 A.M. Sufficient time (15 min) was given to the nonmeditators to relax before recording the parameters. The venues chosen for measurement of parameters were familiar to the subjects.

Blood pressure was recorded using a sphygmomanometer. ECG was recorded by an ECG machine (108 T, BPL) using standard chest and limb leads. Heart rate was calculated from the tracings. Each ECG was reported by a trained physician. In respiratory function, the following parameters were assessed:- tidal volume, vital capacity, breath holding and expiratory pressure. The tests wee thoroughly explained and each subject was given three trials. In case of tidal volume the average of three readings was taken and in cases of vital capacity and breath holding the highest reading was considered. Tidal volume and vital capacity were measured with Wright Respirometer Mark 8 (Farriers Medical Limited, London). Breath holding was measured on a stopwatch till the breaking point of the held breath. Expiratory pressure was recorded through a manometer by the standard procedure.

To assess the lipid profile 5 ml of blood was collected. Serum cholesterol, triglyceride and HDL was estimated by their respective reagent sets from Labcare, Baroda and the readings taken on a RA-50 chemistry analyzer.

Statistical methods used:
Descriptive statistics of mean, standard deviation and percentages were used to display the continuous (age, respiratory functions, cardiovascular parameters, lipid profile) and categorical (sex, physical exercise, smoking, drinking and diet) variables of the three groups respectively. One way analysis of variance was applied to find the significance of differences between the three groups. In addition, the groups significantly different at 5% level by ANOVA were subjected to Bonferroni multiple comparisons procedure. Categorical independent variables were analyzed for association with the three groups using Pearson’s Chi-square test.
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RESULTS

The subjects in the three groups did not show significant difference in age, sex distribution and physical activity (Table I). The dietary habit of meditators showed a significant difference from non-meditators but as the number of non-vegetarians is small (9 out of the 105 subjects) the P value should be interpreted with caution. (Table I) None of the subjects were smokers or consumers of alcohol.

TABLE I: Distribution of demographic characteristics

Variables	Non meditators n(%)	Short term meditators (n%)	Long term meditators n(%)	P
Age (mean ± SD)	52.6±12.2	46.6±13.3	52.9±12.4	0.06
Sex 1. Male         2. Female	12(34.3) 23 (65.7)	12 (34.3) 23 (65.7)	18 (51.4) 17 (48.6)	0.24
Physical Exercise        1. Sedentary        2.Non Sedentary	29 (82.9) 6 (17.1)	29 (82.9) 6 (17.1)	26 (74.3) 9 (25.7)	0.58
Diet Non-Veg         Veg	9 (25.7) 26 (74.3)	0 35 (100)	0 35 (100)	0.00

None were smokers or consumers of alcohol.
Sedentary: No physical exercise; Non Sedentary: Regular physical exercise every day.

TABLE II: Respiratory, cardiovascular and lipid parameters in the groups.

Variables	Non meditators	Short term meditators	Long term meditators	P
Tidal Volume (ml) mean ± SD	272.8±165.0	557.7±220.1*	579.9±140.5*	0.0000
Vital Capacity (ml) mean ±SD	2176.3±844.7	3358.0±905.5*	3931.7±798.8**	0.0000
Breath Holding (sec) median (min., max.)	20.0(5,60)	35 (20,90)*	40 (20,65)*	0.0000
Expiratory pressure (mmHg) mean ± SD	53.9±27.8	65.1±30.3	91.5±33.3**	0.0000
Systolic Blood Pressure (mmHg) mean ± SD	133.7±17.1	137.8±17.4	140.7±20.9	0.2857
Diastolic Blood Pressure (mmHg) mean ±SD	92.7±8.6	87.1±10.2*	84.0±7.1*	0.0003
Heart Rate (min.) mean ± SD	84.7 ±12.6	90.8±11.8	74.6±10.6	0.0000
Cholesterol (mg/dl) mean ± SD	293.0±67.9	240.6±69.1*	235.4±94.5*	0.0040
Triglyceride (mg/dl) median (min. max.)	141.5 (64,2,435.3)	105 (19,409.4)	123 (51,212.6)	0.0401
HDL  (mg/dl) median (min. max.)	46 (24, 120)	44 (24,99)	52 (38,76)	0.2431

*significantly different at 5% level from Non mediators.
*significantly different at 5% level from Short term meditators.

Table II shows that tidal volume, vital capacity and breath holding are significantly higher in short and long term meditators as compared to non meditators. Only vital capacity and expiratory pressure are significantly higher in long term meditators as compared to short term meditators. Diastolic blood pressure is significantly lower in both short and long term meditators as compared to non-meditators. Heat rate is significantly lower in long-term meditators as compared to non-meditators and short term meditators. Systolic blood pressure shows no significant difference between the three groups.

Electrocardiogram showed no particular pattern or significant changes except for changes in heart rate. Cholesterol is significantly lower in both short and long term meditators as compared to non-meditators. Though triglyceirde showed a significant P value with ANOVA, further analysis with Bonferroni test showed no significant difference between the three groups. There was no significant difference in HDL values between the three groups.
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DISCUSSION

Improvements in cardio respiratory parameters and lipid profile seen in the meditators in our study are similar to other studies done on meditation (3, 4, 5) and yoga (6, 7). Although clear cut evidence is lacking, the mechanisms by which changes in respiratory functions occur are: greater relaxation of respiratory muscles induced by supraspinal mechanisms which increase expiratory reserve volume contributing to a rise in vital capacity.

Lung inflation to near total lung capacity is a major physiological stimulus for release of surfactant and prostaglandin into alveolar spaces. This causes increase in lung compliance and a decrease in bronchiolar smooth muscle tone (8, 9). Lung inflation to near total lung capacity as induced by relaxation during meditation may thus lead to a better vital capacity. The increased breath holding time caused by greater control of respiratory musculature and the ability to consciously override the normal physiological stimuli of respiratory centers has been reported in the study on those doing yoga (10). Perhaps a similar mechanism comes to play here.

The wakeful hypo-metabolic state as characterized by decreased CO₂ production and decreased O₂ consumption can also help to hold the breath for a longer time. (3, 11). The decrease in heart rate and diastolic blood pressure indicate a shift in the balancing components of autonomic nervous system towards the parasympathetic state (1). Meditation by modifying the state of anxiety (1) reduces stress induced sympathetic over activity resulting in a lowering of diastolic blood pressure and heart rate. It makes the subject undergo relaxation and thereby decrease arterial tone and peripheral resistance (12, 13). This may be another reason for a fall in diastolic blood pressure.

Long-term meditation seems to confer further improvement of certain parameters measured (vital capacity, expiratory pressure and heart rate) indicating a continued alteration of the physiological processes involved.

Our findings on changes in the cholesterol level are similar to those reported in transcendental meditation (2, 14). A decrease in sympathetic discharge and better ability to overcome stress can be cited as possible mechanisms for this change. Even though in our subjects the level of physical activity was similar the meditators had a significantly lower cholesterol level.

In summary our study indicates that Raja Yoga meditation confers significant benefits in respiratory functions, cardiovascular parameters and lipid profile which continued to improve further with long-term meditation.

ACKNOWLEDGEMENTS

We thank all the subjects for their cooperation and all of the stall of the Department of Physiology, B. J. Medical College, Ahmedabad especially Dr. C. A. Desai, former Professor and Dean Dr. R. C. Shah and Dr. K. V. Raval for the help rendered.
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REFERENCES

1. Anand BK. Yoga and medical science. Indian J Physiol Pharmacol 35(2): 1991; 84-87.
2. Cooper MJ, Aygen MM. A relaxation technique in the management of hypercholesterolemia. J Human Stress 1979 Dec; 5(4): 24-27.
3. Chakrabarti, Ghosh, Sahana. Physiological changes during meditation. In: Chakrabarti, Ghosh and Sahana’s Human Physiology: 2^nd Edition 1984; 1236-1244.