Prof. J.P.N. Mishra
Sakakibara et al (1996) studied Effect of slowed respiration on cardiac parasympathetic response to threat. The present study was designed to examine the effect of voluntarily slowed respiration on the cardiac parasympathetic response to a threat: the anticipation of an electric shock. The amplitude of the high frequency (HF) component of the heart rate variability, an index of cardiac parasympathetic tone, significantly decreased during the threat in the fast and non-paced breathing groups, whereas it was unchanged in the slow paced breathing group. No significant difference was observed among the three groups in the amplitude of respiration during the threat. Results suggest that a slowed respiration decreases the cardiac parasympathetic withdrawal response to the threat. This study provides a rationale for the therapeutic uses of the slowed respiration maneuver in attenuating the cardiac autonomic responses in patients with anxiety disorder.
In a scientific study conducted by Vempati et al (1994) 35 male volunteers with ages ranged from 20 to 46 yrs were studied in two sessions, of yoga based guided relaxation and supine rest. Assessments of autonomic parameters were made in 15 subjects, before, during and after the practices, whereas oxygen consumption and breath volume were recorded in 25 subjects, before and after both types of relaxation. A significant decrease in oxygen consumption and increase in breath volume were recorded after guided relaxation (paired t test). There were comparable reductions in heart rate and skin conductance level during both types of relaxation. During guided relaxation the power of the low frequency (LF) component of the heart rate variability spectrum reduced, whereas the power of the high frequency (HF) component increased, suggesting reduced sympathetic activity. Also subjects with a base line ratio of LF/HF >0.5 showed a significant decrease in the ratio after guided relaxation, while subjects with a ratio < 0.5 at baseline showed no such change. The results suggest that sympathetic activity decreased after guided relaxation based on yoga, depending on the base line levels.
Telles et al (1994) studied in seven experienced meditators (with experience ranging from 5 to 20 years). Each subject was studied in two types of sessions - meditation (with a period of mental chanting of "OM") and control (with a period of non-targeted thinking). The meditators showed a statistically significant reduction in heart rate during meditation compared to the control period (paired "t" test). During both types of sessions there was a comparable increase in the cutaneous peripheral vascular resistance. Keeping in mind similar results of other authors, this was interpreted as a sign of increased mental alertness, even while being physiologically relaxed (as shown by the reduced heart rate).
Bera and Rajpurkar (1993) scientifically investigated Body composition, cardiovascular endurance and anaerobic power of yogic practitioner. They reported that yoga training results in significant improvement in cardiovascular endurance and anaerobic threshold.
Telles et al (1993) studied the heart rate alterations in different types of pranayama. The report presents the differences in heart rate changes in 4 different kinds of pranayama, practiced by a subject who had several years of experience. The results revealed an overall increase of heart rate during two of the four Pranayama, compared to the respective pre-pranayamic baseline values of the sukhasana sitting state. These 2 Pranayama have end-inspiratory kumbhaka, and have only a short end-expiratory kumbhaka. In the other two Pranayama the two varieties, which had end-inspiratory and end-expiratory kumbhaka phases, the mean of overall heart rate was not significantly altered. They found that, in two Pranayama the heart rate was more during inspiration and less during expiration. Both values were significantly higher than corresponding values of quiet breathing in the preceding baseline period. In the remaining Pranayama the heart rate was higher during expiration than during inspiration. However, the highest value was during the end-inspiratory kumbhaka and lowest during-expiratory kumbhaka. The inspiratory and expiratory heart rate values did not differ significantly from the corresponding values of the preceding baseline period.
Khalsa et al (1993) conduct three experiments to monitor the effects of unilateral forced nostril breathing (UFNB) on the heart. Experiment 1 includes 7 subjects (4 males, 3 females) with a respiratory rate of 6 breaths/min (BPM). Experiment 2 includes 16 trials using one subject to examine the intra-individual variability, at 6 BPM. Experiment 3 includes 10 trials with the same subject in experiment 2, but with a respiratory rate of 2-3 breaths/s. This rapid rate of respiration is a yogic breathing technique called "breath of fire" or kapalabhati and employs a very shallow but rapid breath in which the abdominal region acts like a bellows. All 3 experiments demonstrated that right UFNB increases heart rate (HR) compared to left. Experiment 1 gave 7 negative slopes, or lowering in HR with left nostril breathing and 7 positive slopes, or increases in HR with right nostril breathing, p =.001. The second and third experiments showed differences in HR means in which right UFNB increases HR more than left, p =.013, p =.001, respectively. In experiment 2 stroke volume was higher with left UFNB, p =.045, compensating for lower HR. Left UFNB increased end diastolic volume as measured in both experiments 1 and 2, p =.006, p =.001, respectively. These results demonstrate a unique unilateral effect on sympathetic stimulation of the heart that may have therapeutic value.
Telles et al (1992) in their another study noted a significant increase in heart rate during the 'single thought' state compared to the baseline (eyes closed sukhasan), and a further increase during the 'no thought' state. In contrast, the changes in respiration were different for the 2 states: during 'single thought' state there was an increase in rate and regularity of respiration, whereas during the 'no thought' state there was a significant reduction m the rate and regularity. It is noteworthy that although the respiratory changes are in opposite directions, the heart rate changes are in the same direction (increase). This is an example showing changes of heart rate and respiration accompanying a yogic subjective activity intended to alter the state of mind alone.
Cusumano et al (1992) in his study explored the effects of hatha yoga and progressive relaxation on heart rate, blood pressure, physical self-efficacy, and self-esteem. Ninety-five female Japanese undergraduates participated in the three weekly treatment sessions. Results showed that both treatments were effective in lowering heart rate and blood pressure and increasing self-esteem; however, perceptions of physical self-efficacy declined over time. No significant differences were found between the treatments
Blumenthal et al (1991) studied effects of exercise training on cardiorespiratory function in men and women older than 60 years of age. This study reports the physiologic effects of up to 14 months of aerobic exercise in 101 older (greater than 60 years) men and women. After an extensive baseline physiologic assessment (Time 1), in which aerobic capacity and blood lipids were measured, subjects were randomized to an aerobic exercise condition (cycle ergometry, 3 times per week for 1 hour), nonaerobic yoga (2 times per week for 1 hour), or a waiting list nonexercise control group for 4 months, and then underwent a second (Time 2) assessment. At the completion of the second assessment, all remaining subjects completed 4 months of aerobic exercise and were reevaluated (Time 3). Subjects were given the option of participating in 6 additional months of supervised aerobic exercise, and all available subjects completed a fourth assessment (Time 4) 14 months after their initial baseline evaluation. Results indicated that subjects generally exhibited a 10 to 15% improvement in peak oxygen consumption after 4 months of aerobic exercise training, and a 1 to 6% improvement in aerobic power with additional aerobic exercise training. On the other hand, subjects, especially men, continued to have improvements in sub-maximal exercise performance (i.e., anaerobic threshold). In addition, aerobic exercise was associated with an improved lipid profile; subjects participating in aerobic exercise for up to 14 months exhibited increased levels of high-density lipoprotein cholesterol. Maintenance of regular aerobic exercise for an extended time interval is associated with greater cardiovascular benefits among older adults than has been reported previously.
Stancak et al (1991) studied cardiovascular and respiratory changes during yogic breathing exercise kapalabhati (KB) in 17 advanced yoga practitioners. The results point to decreased cardiac vagal tone during KB, which was due to changes in respiratory pattern and due to decreased sensitivity of arterial baroreflex. Decreased respiratory rate and increased SBP and low-frequency blood pressure oscillations after KB suggest a differentiated pattern of vegetative activation and inhibition associated with KB exercise
Sudsuang et al (1991) evaluated serum Cortisol and total protein levels, blood pressure, heart rate, lung volume, and reaction time in 52 males, 20-25 years of age, practicing Dhammakaya Buddhist meditation, and in 30 males of the same age group not practicing meditation. It was found that after meditation, serum Cortisol levels were significantly reduced, serum total protein level significantly increased, and systolic pressure, diastolic pressure and pulse rate significantly reduced. Vital capacity, tidal volume and maximal voluntary ventilation were significantly lower after meditation than before. There were also significant decreases in reaction time after meditation practice. The percentage decrease in reaction time during meditation was 22%, while in subjects untrained in meditation; the percentage decrease was only 7%. Results from these studies indicate that practicing Dhammakaya Buddhist meditation produces biochemical and physiological changes and reduces the reaction time. Most studies of Transcendental Meditation (TM), Zen Buddhist sitting, Herbert Benson's "relaxation response," and other calming forms of meditation indicate that meditating subjects generally experience a lowering of the heart rate. The results of such studies vary to some degree, since they depend on different kinds of subject groups and various experimental procedures, with some showing an average decline of seven beats or more per minute among their subjects and some showing two or three beats per minute among some of their subjects.
Blumenthal et al (1989) examined the cardiovascular and behavioral adaptations associated with a 4-month program of aerobic exercise training in 101 older men and women (mean age = 67 years). Subjects were randomly assigned to an aerobic exercise group, yoga and flexibility control group, or a waiting list control group. Prior to and following the 4-month program, subjects underwent comprehensive physiological and psychological evaluations. Physiological measures included measurement of blood pressure, lipids, bone density, and cardiorespiratory fitness including direct measurements of peak oxygen consumption (V02) and anaerobic threshold. Psychological measures included measures of mood, psychiatric symptoms, and neuropsychological functioning. This study demonstrated that 4 months of aerobic exercise training produced an overall 11.6% improvement in peak V02 and a 13% increase in anaerobic threshold. In contrast, the yoga and waiting list control groups experienced no change in cardio-respiratory fitness. Other favourable physiological changes observed among aerobic exercise participants included lower cholesterol levels, diastolic blood pressure levels, and for subjects at risk for bone fracture, a trend toward an increase in bone mineral content. Although few significant psychological changes could be attributed to aerobic exercise training, participants in the two active treatment groups perceived themselves as improving on a number of psychological and behavioral dimensions.
Cort (1989) has hypothesized that the large the variability of results in different studies on the effect of meditation on hypertension may be due to differences in compliance to the meditation regimens. This study of fifty-one black adults supports the claim that greater compliance to a meditation program leads to greater decreases in blood pressure.
Bhargava et al (1988) have shown that base line heart rate and blood pressure (Systolic and Diastolic) showed a tendency to decrease and both these autonomic parameters were significantly decreased at breaking point after pranayamic breathing. Although the GSR was recorded in all subjects the observations made were not conclusive. Thus Pranayama breathing exercises appear to alter autonomic responses to breathe holding probably by increasing vagal tone and decreasing sympathetic discharges.
Bhargava (1988) observed autonomic responses to breath holding and its variations following pranayama. Autonomic responses to breath holding were studied in twenty healthy young men. Breath was held at different phases of respiration and parameters recorded were breath holding time, heart rate systolic and diastolic blood pressure and galvanic skin resistance (GSR). After taking initial recordings all the subjects practiced Nadi-Shodhana Pranayama for a period of 4 weeks. At the end of 4 weeks same parameters were again recorded and the results compared. Baseline heart rate and blood pressure (systolic and diastolic) showed a tendency to decrease and both these autonomic parameters were significantly decreased at breaking point after pranayamic breathing. Although the GSR was recorded in all subjects the observations made were not conclusive. Thus pranayama appear to alter autonomic responses to breathe holding probably by increasing vagal tone and decreasing sympathetic discharges.
Shrikrishna (1985) has scientifically investigated the essence of pranayama and stated that different practices of pranayama do show widespread effects on the various body functions and the changes in the respiratory cardio-vascular, biochemical, metabolic, and neural functions. The changes in the respiratory functions during these practices are of such a nature that they do not lead to any significant disturbance in the body homeostasis. Their effect on the level of oxygen and carbon dioxide in the blood doesn't show any significant change. Thus confirming that though these practices involves a lot of change in the respiratory parameters like respiration rate, tidal volume, minute ventilation etc. they actually do not making more oxygen available to the body (unless the previous values are abnormally low due to some disease state like bronchial asthma).
The real value of pranayama is not its oxygen value but its effect on the nervous system. The observation on the effect of pranayama on cardio-vascular, biochemical and metabolic functions shows that the magnitude of the response depends on the physical efforts involved in the different techniques of pranayama. The intensity of these responses is least in Ujjayi pranayama and highest in kapalabhati kriya with bhastrika pranayama in between. However all the practices lead to identical neural response in the form of increased Alpha pattern of the brain waves as seen in EEG. This increase in alpha waves all over the brain is called synchronization and it was always more when objects reported a subjective feeling of more mental calmness and alert restfulness.
Delmonte et al (1985) reviewed the research findings on biochemical responsivity to meditation. Although there are some contradictory and inconclusive outcomes, there is nevertheless sufficient evidence of interest to warrant further investigation of this area. However, in the meantime, there is no compelling basis to conclude that meditation practice is associated with special state or trait effects at the biochemical level. Biochemical markers examined included: blood lactate and blood flow; Cortisol, testosterone, growth hormone, thyroxine and triiodothyronine; plasma rennin, aldosterone and dopaminebetahydroxylase; catecholamines; serum cholesterol; plasma phenylalanine; neurotransmitter metabolites; prolactin; salivary translucency, proteins, minerals and pH.
According to Delmonte et al (1984), meditation has been extensively researched in terms of physiological responsivity. Although practice is associated with both state and trait (long-term) decrements in arousal (especially in blood pressure, muscle tension and respiratory indices) there is, generally, no compelling evidence to suggest superiority to other established relaxation techniques (except, perhaps, in the case of blood pressures). At best, meditation appears to be somewhat more relaxing than eyes-closed rest. There is little to support the notion of unique state effects associated with practice. However, meditators appear to show stronger recovery responses to stressful stimuli than controls. Meditation is increasingly gaining prominence as a self-management and personal development technique as well as becoming more prevalent in the clinical setting as an adjunct to psychotherapy. This is particularly true in the case of Transcendental Meditation (TM) and its non-cultic or clinically adapted variants. However, there is no extensive up-to-date review of the research literature dealing with the psycho-physiological effects of meditation practice.
Cummings (1984) observed reduced heart rates for those practicing a combination of meditation and exercise.
Throll (1982) has stated that a Transcendental meditation group displayed a more significant decrease in heart rate than a group using Jacobson's progressive relaxation. Another study in the sequence showed a decrease in heart rate during meditation.
Bono (1984) reported that the reduction of heart rate during TM was greater than the reduction resulting from sitting quietly with eyes closed.
Delmonte (1984f) found that heart rates were slightly lower during meditation than rest for fifty-two subjects. Holmes et al (1983), however, found that while meditators had lower heart rates while practicing TM, they did not experience lower arousal than control subjects who were simply resting. These findings were also supported by Dillbeck and Orme-Johnson (1987), Morrell (1986), and Holmes (1984).
It has been reported by Madanmohan et al (1983), Rai et al (1982), and Gopal et al (1973) that Pranayama improves cardiorespiratory functions.
Wallace et al (1983) measured systolic blood pressure using a standard mercury sphygmomanometer on 112 transcendental meditators. The subjects had a mean systolic blood pressure 13.7 to 24.5 less than the population mean. The analysis also showed that meditators with more than five years of experience had a mean systolic blood pressure 7.5 lower than meditators with less than five years of experience.
Bagga and Gandhi (1983) found an average decline as high as fifteen beats per minute among some of their subjects. Some studies indicate that meditation lowers the heart rate more than biofeedback, progressive relaxation, other therapies, or simple sitting, while other studies indicate that these various activities have an equivalent effect on the heart rate. Once again, such differences in outcome can be accounted for by differences among subjects and experimental designs. A decline in heart rate is more pronounced among experienced meditators, according to a few studies, though here too the evidence is not unanimous. The only generalization we can make safely now is that some subject groups demonstrate an average lowering of heart rate during meditation, and that some experienced individuals may achieve a permanent lowering of the heart rate with continued practice.
Bagga and Gandhi (1983) compared groups of six TM practitioners and six shavasana practitioners (relaxing while lying on one's back) with six controls, and found significantly reduced heart rates for both experimental groups versus the control group.
Hafner (1982) assessed twenty-one hypertension patients who had been randomly assigned to eight one-hour sessions of meditation training, meditation plus biofeedback-aided relaxation, or a non-treatment control group. Statistically significant fall in systolic and diastolic blood pressure occurred after both training programs, although overall reductions in blood pressure were not significantly greater in either program than in the control group. Meditation plus biofeedback-aided relaxation produced falls in diastolic blood pressure earlier in the training program than did meditation alone. All patients practiced meditation regularly between training sessions, but the amount of practice did not correlate with the amount of blood pressure reduction after training.
Muralidhara and Ranganathan (1982) concluded that yoga training improves physical efficiency as indicated by significant increase in cardiac recovery index measured by Harvard step test.
Pollard and Ashton (1982) divided sixty subjects into six groups in a comparison of heart rate decrease obtained by visual feedback, auditory feedback, combined visual and auditory feedback, instructions to decrease heart rate without biofeedback, sitting quietly, and abbreviated relaxation training. A comparison group of meditators with a minimum of six years of experience was also studied. The results indicated that there was no advantage of a heart rate decrease task for subjects receiving visual, auditory, or combined biofeedback, though all groups showed evidence of a decline in heart rate over the testing session. The meditation group showed the greatest overall decline, with a decrease in heart rate of approximately seven beats per minute, versus three beats per minute for the groups using biofeedback techniques.
Cuthbert et al. (1981) had results demonstrating clear superiority for meditators using Benson^ relaxation response versus heart rate biofeedback, especially when the subject experimenter relationship was supportive. Lang et al (1979) placed the heart rate decrease for advanced TM meditators with more than four years of practice at 9%. Bauhofer (1978) found that the heart rates of experienced TM meditators were lowered by TM more than those of less experienced TM meditators. Corey (1977) and Routt (1977) reported that Transcendental Meditation appeared to decrease heart rate under nonstress conditions. Glueck and Stroebel (1975), Wallace and Benson (1972), Wallace et al (1971), and Wallace (1971) found that the heart rate decreased from three to five beats per minute during Transcendental Meditation. Reports of reduced heart rates during meditation extend back to Paul (1969), Karambelkar et al (1968), Anand and Chhina (1961), Wenger and Bagchi (1961), Bagchi and Wenger (1957), and Das and Gastaut (1955).
Seer and Raeburn (1980) conducted a research in which forty-one un-medicated hypertensive's were randomly assigned to three groups: TM training, placebo control (TM training without a mantra), and no-treatment control. The results showed modest reductions in blood pressure in both treatment groups, compared with no treatment, with diastolic percentage reductions reaching significance. There was considerable subject variation in response, with an overall mean decline in diastolic blood pressure of 8-10% on a three-month follow-up.
Surwit et al (1978) compared the separate effects of three procedures for the reduction of high blood pressure in three treatment groups of eight patients, each with medically verified borderline hypertension. The three treatment groups used the following procedures: (a) biofeedback for simultaneous reductions in systolic blood pressure and heart rate; (b) biofeedback for reductions in integrated forearm and frontalis muscle electromyography activity; and (c) meditation relaxation based on the relaxation response procedure developed by Herbert Benson. Each patient was studied in two baseline sessions, eight training sessions, and a six-week follow-up.
Half of the sample returned for a one-year follow-up. Analysis of variance of the three treatment groups over eight training sessions, with twenty trials per session, revealed significant effects for trials within sessions. However, there were no significant main effects or interactions related to differences between the treatment conditions or to changes in blood pressure over the course of training sessions. Although all groups showed moderate reductions in blood pressure as compared to initial values, no technique could be seen to produce a reduction in pressure greater than that observed in the baseline sessions. Blood pressures of patients reporting for the one-year follow-up were not different from pre-treatment baseline levels.
In a study conducted by Pollack et al (1977) twenty hypertensive patients, nine of whom were on stable dosages of hypotensive medication, were taught TM. Blood pressure reductions were 10 mmHg systolic/2 mmHg diastolic after three months and 6 mmHg systolic/2 mmHg diastolic after six months. The only statistically significant reduction in blood pressure occurred after three months. Meditation plus biofeedback produced decreases in diastolic blood pressure earlier in the training program than meditation alone.,
Blackwell et al (1976) conduct a study in which seven selected hypertensive patients were stabilized on drugs at a research clinic. Subjects learned transcendental meditation (T.M.), were seen weekly, and took their own blood pressure several times daily. After 12 weeks of T.M. six subjects showed psychological changes and reduced anxiety scores. Six subjects also showed significant reductions in home and four in clinic blood-pressures. Six months later four subjects continued to derive psychological benefit and two showed significant blood-pressure reductions attributable to T.M. at home and clinic.
Patel (1975) selected thirty-two subjectstwenty-one females and eleven malesbetween the ages of thirty-four and seventy-five years with essential hypertension of known duration from six months to thirteen years, were randomly divided into a treatment group and a control group. Fourteen subjects in the treatment group and fifteen in the control group were receiving antihypertensive drugs. Baseline blood pressure was first obtained after a twenty-minute rest in the supine position. The patients were given two stress tests: an exercise test (climbing a nine-inch step twenty-five times) and a cold press or test (immersing the left hand in cold water after alerting the patient sixty seconds in advance) at the beginning and again after six weeks.
Blood pressure was taken during the alert, at the end of each test, and every five minutes until it returned to the original value or up to a maximum of forty minutes. In the six weeks between test periods, all subjects attended a twice-weekly training sessions. The treatment group was given training in relaxation and meditation based on yogic principles, which was reinforced with biofeedback instruments, and group members were asked to practice relaxation and meditation at home twice daily for twenty minutes. In the treatment group there was a significant reduction in the pressure rises as well as in recovery time. Mere repetition of the tests did not influence these indications of stress. When the differences between the groups were compared, all measurements except the systolic pressure rise after exercise showed significant improvement in the treated group.
Udupa et al (1975) have reported a decrease in pulse rate but no change in blood pressure after short duration pranayama training.
Patel et al (1975) conduct a scientific study on 34 hypertensive patients for six weeks of yoga methods with biofeedback or to general relaxation and showed a reduction in blood-pressure although the decrease was significantly greater for the yoga group. The control group was then trained in yoga relaxation and their blood-pressure fell to that of the other group.
Benson et al (1974) found that twenty-two borderline hypertensive not using drugs when taught TM, their mean blood pressure decreased from 146.5/94.6 mmHg during the premeditation control period, lasting 5-7 weeks, to 139.6/90.8 mmHg during the post-meditation experimental period, lasting an average of twenty-five weeks. They were tested throughout the premeditation and post meditation periods.
Benson et al (1974) have stated that fourteen hypertension subjects, on drugs were taught the relaxation response. During a control period of 5.6 weeks, blood pressure did not change significantly from day to day, and averaged 145.6/91.9 mmHg. During an experimental period of twenty weeks, blood pressure decreased to 135.0/87.0 mmHg.
Patel (1973) has stated that when twenty hypertension patients using hypotensive drugs were taught yoga, breath meditation, muscle relaxation, and meditation concentration, their average blood pressure was reduced from 159.1/100.1 ramHg to 138.7/85.9 mmHg. The average blood pressure of twenty control subjects, who rested on a couch for the same number of sessions and who were given no relaxation training, was reduced from 163.1/99.1 mmHg to 162.6/97.0 mmHg.
Benson and Wallace (1972) have said that twenty-two hypertensive with no meditation experience were given the standard TM training. Their mean blood pressure before meditation was 150/94 mmHg. After four to sixty-three weeks of meditation practice their mean blood pressure was reduced to 141/87 mmHg.
Datey et al (1969) has concluded that 47 subjects practicing Shavasana, for approximately thirty weeks, of these forty-seven subjects, ten who did not use antihypertensive drugs had an average systolic blood pressure reduction from 134 to 107 mmHg. A second group of twenty-two subjects, with blood pressure well controlled by antihypertensive drugs, had an average systolic blood pressure reduction from 102 to 100 mmHg. A third group of fifteen subjects, with inadequately controlled blood pressure using antihypertensive drugs, had an average systolic blood pressure reduction from 120 to 110 mmHg. The subjects' average drug requirement was reduced to 32% of the original dosages for the second group. In group three, six patients reduced their drug requirement to 29% of the original, seven patients' dosages were unchanged, and two patients required an increased dosage
