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Indian
J Physiol Pharmacol 2003; 47 (1): 27-33
Effect
of Pranayam Training on Cardiac Function in Normal
Young Volunteers
KAVIRAJA UDUPA, MADANMOHAN*, ANANDA
BALAYOGI BHAVANANI,
P. VIJYALAKSHMI AND N. KRISHNAMURTHY
VIJAYALAKSHMI AND N. KRISHNAMURTHY
Department of Physiology,
Jawaharlal Institute of Postgraduate
Medical
Education & Research (JIPMER), Pondicherry - 605 006
(Received on June
16, 2002)
Abstract: Systolic tire intervals (STI) are non-invasive
and sensitive tests for measuring the ventricular performance.
It has been reported that practice of pranayam modulates
cardiac autonomic status and improves cardio-respiratory functions.
Keeping this in view, the present study was designed to determine
whether pranayam training has any effect on ventricular
performance as measured by STI and cardiac autonomic function
tests (AFT). Twenty-four school children were randomly divided
into two groups of twelve each. Group I (pranayam group)
subjects were given training in nadishuddhi, mukh-bhastrika,
pranav and savitri pranayams and practised the
same for 20 minutes daily for a duration of 3 months. Group II
(control group) subjects were not given any pranayam training.
STI (QS2, LVET and PEP) and AFT (RRIV and QT/QS2)
were measured in both the groups at the beginning and again at
the end of three months study period. Pranayam training
produced an increase in RRIV and a decrease in QT/QS2
suggesting an enhanced parasympathetic and blunted sympathetic
activity respectively. QS2, PEP and PEP/LVET increased
significantly, whereas LVET was reduced significantly in pranayam
group. In contrast, the changes in STI and AFT were much less
marked in the control group. Our study shows that three months
of pranayam training modulates ventricular performance
by increasing parasympathetic activity and decreasing sympathetic
activity. Further studies on a larger sample size may illustrate
the underlying mechanism(s) involved in this alteration.
Keywords: pranayam, systolic, time intervals, RRIV, QT/QS2
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
INTRODUCTION
With increased awareness and interest in health and natural
remedies, yogic techniques including pranayams are gaining
importance and becoming increasingly acceptable to the scientific
community. There is evidence that pranayam training produces
deep psychosomatic relaxation (1, 2) and improvement of cardio-respiratory
efficiency (3). Chhina has reported that yogis are capable of
controlling their autonomic functions (4) and Raghuraj et al have
found that practice of nadishuddhi pranayam results
in alteration of autonomic balance (5). Telles et al have demonstrated
that pranayam breathing through right nostril results in
an increase in sympathetic activity whereas left nostril breathing
reduces it (6).
Systolic time intervals (STIs) are useful, reproducible and
non-invasive measures of left ventricular function (7, 8). It
is interesting to note that the term "noninvasive" was
first used in connection with the STIs which are the earliest
quantitative non-invasive tests used for the determination of
cardiac function (7). To the best of our knowledge there is no
scientific report on the effect of pranayams on STI. Hence,
the present study was designed to study the effect of pranayams
on cardiac performance as measured by STI. Since, pranayams
are known to influence the cardiac function by modulating
autonomic activity (4, 5, 6), we also included in the present
study, autonomic function tests (AFT) i.e. RR interval variation
(RRIV) and QT/QS2) which are the indicators of parasympathetic
and sympathetic activity respectively (9, 10). The objectives
of the present study were
(i)to
study the effect of pranayam training on ventricular function
as assessed by STI.
(ii)To
explain these effects, (if any) in terms of alteration of cardiac
autonomic status by studying the effects of pranayam on
RRIV and QT/QS2.
To study the effect of pranayam training on ventricular function
as assessed by STI.
To explain these effects, (if any) in terms of alteration of cardiac
autonomic status by studying the effects of pranayam
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METHODS
Twenty-four healthy boys were recruited for the present study.
Their age was 13-15 (14.5 ± 0.25, SEM) years, weight 36-43 (39.28
± 1.36, SEM) kg and height 154 – 161 (157 ± 0.2, SEM) cm. After
explaining the purpose and design of the study, informed consent
was obtained from them as well as their parents. None of the
subjects had been engaged in yoga practice in the past nor were
they doing any physical exercise prior to this study period.
The subjects were randomly assigned to two groups of twelve each.
Group I (pranayam group) subjects were taught nadishuddhi,
mukh-bhastrika, pranav and savitri pranayams by a qualified
yoga teacher and practised the same for twenty minutes daily,
five days a week for a total duration of three months under our
direct supervision. Descriptions of the techniques of these pranayams
are given elsewhere (11, 12). Group II (control group) subjects
were not taught pranayam and did not practice the same.
On the day of the test, subjects reported at our laboratory two
hours after a light breakfast. Recordings were taken at laboratory
temperature of 27 ± l ºC. After ten minutes of supine rest, heart
rate (HR), systolic pressure (SP), diastolic pressure (DP), STI
and AFT were performed as described below.
Heart rate & blood pressure: To avoid observer bias in the measurements,
HR and blood pressure were recorded using automatic non-invasive
blood pressure apparatus (Press-Mate BP 8800, Colin Corporation,
Japan). Rate-pressure-product (RPP), which is an index of
myocardial oxygen consumption (13) was calculated as a product
of HR and SP divided by 100 (RPP = HR x SP x 10-2).
Systolic time intervals: STIs were calculated by simultaneous recording of electrocardiogram
(ECG), phonocardiogram (PCG) and carotid arterial pulse. Lead
II ECG was recorded with conventional electrodes. PCG was recorded
with PCG transducer (TA-701T, Nihon Kohden Corporation, Japan) placed over 2nd intercostal space at right
end of the sternum. Carotid arterial pulse was recorded with
a transducer (TK701 T, Nihon Kohden Corporation, Japan) positioned
over a point of maximal pulsation of right carotid artery between
the sternoclavicular joint and angle of jaw with the subjects
face turned slightly towards the left shoulder (14). The signals
were fed into 8-channel polygraph (RM 6000, Nihon Kohden Corporation,
Japan) and converted into digital format
using analog-digital converter (Mi2,USA). Ten seconds of recording strip having clear wave fronts were stored
and analyzed later on with the help of data processing software
(Biowindows, Modular Instruments Inc. USA). With this software STIs can be calculated
with an accuracy of 1ms. Electromechanical systole (QS2
) was calculated from the beginning of the Q wave of ECG to the
first high frequency component of second heart sound (Fig. 1).
Left ventricular ejection time (LVET) was expressed as the interval
between the upstroke of the carotid pulse and the dicrotic notch.
Pre-ejection period (PEP) was calculated from the difference between
QS2 and LVET. These three STIs and PEP/LVET ratio
were computed for each cardiac cycle and average of ten continuous
cardiac cycles was taken for statistical analysis (7). Since
STIs are known to vary with HR, their index values need to be
calculated for proper interpretation of the results. Index values
for QS2, LVET and PEP were calculated by applying
Weissler's regression equation (15) as follows :
QS2I = 2.1 (HR) + QS2;
LVETI = 1.7 (HR) + LVET;
PEPI = 0.4 (HR) + PEP
click for full view |
Fig. 1: Upper tracing: lead II Electrocardiogram, middle
tracing: phonocardiogram and lower tracing: carotid arterial
pulse. QS2 : electromechanical systole, LVET,
left ventricular ejection time.
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Autonomic function tests: For calculating RRIV, 150 successive R-R intervals were
recorded under resting conditions and their mean and standard
deviation (SD) were calculated. The coefficient of variation
of RR interval sequence was calculated by the formula: SD/mean
x 100 (9). For calculating QT/QS2 ratio, QT interval
was calculated from the onset of Q wave to the termination of
the T wave. When end of the T wave was not very discrete, T wave
termination was found by drawing a tangential line to the steepest
descent of the T wave. The point at which this tangent intersects
the isoelectric baseline was considered as the termination of
the T wave (10). QT and QS2 were calculated for ten
consecutive cardiac cycles and average QT/QS2 ratio
was determined.
The
data was subjected to statistical analysis using Student's paired
"t" test. A p value of less than 0.05 was accepted
as indicating significant difference between the compared values.
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RESULTS
The results are given in Table I. In group I, pranayam
training produced a significant decrease in basal HR, the difference
being statistically significant (P<0.01). On the other hand
there was no significant change in the basal HR in group II.
SP and DP did not change much in either group. RPP showed significant
decrease in pranayam group (P<0.01) whereas in the control
group the decrease in RPP was not statistically significant.
Pranayam training produced significant increase in QS2
and QS2I (P<0.05) and significant decrease in LVET
and LVET1 (P<0.05). On the other hand there was no significant
change in these parameters in the control group. PEP, PEPI and
PEP/LVET ratio increased significantly in the pranayam
group (P<0.001). In the control group there was a less significant
increase in these values (P<0.05). In group I RRIV increased
by 19% following pranayam training whereas in group II
it increased only by 2%, Pranayam training produced a significant
decrease in QT/QS2 ratio (P<0.001) in group I subjects
whereas in the control group it did not change after three months
of the study period.
click for full view |
Table I: Cardiovascular function in the two groups before
and after three months study period
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DISCUSSION
It has been reported that pranayam improves cardiorespiratory
functions (1, 2, 3) and alters autonomic status (4, 5, 6). Since
there is no report on the effect of pranayam on STIs, we
planned to study the effect of pranayam training on ventricular
performance as measured by STIs. In our group I subjects, pranayam
training of three months duration resulted in a significant reduction
in basal HR. In contrast, there was no change in basal HR of
control subjects (Table 1). pranayam training did not
produce any change in basal SP and DP. Our findings are consistent
with those of' Udupa et al (16) who have reported a decrease in
pulse rate but no change in blood pressure after pranayam
training. RPP is a known indicator of myocardial oxygen consumption
and load on the heart (13). A significant decrease in RPP following
pranayam training in group I subjects indicates a reduction
in work done by the heart. In an earlier study, we have demonstrated
that pranayam produces a significant decrease in oxygen
consumption (1, 2). Raju et al have also reported that pranayam
training results in decrease in oxygen consumption (17). These
studies show that pranayam training produces an overall
reduction in oxygen consumption, metabolic rate and load on the
heart.
Pranayam breathing has been shown to alter the autonomic activity. Telles et al
have demonstrated that pranayam breathing through right
nostril results in an increase in sympathetic activity whereas
left nostril breathing reduces it (6). Raghuraj et al have reported
that slow pranayam (nadishuddhi) increases parasympathetic
activity whereas fast pranayam (kapalabhati) increases
the sympathetic activity (5). Since Udupa et al (16) have reported
that fast and slow pranayams have synergistic effects,
we clubbed fast and slow pranayam in the present study.
Pranayam training in our subjects produced a significant
decrease in QT/QS2 and this indicates a decrease in
cardiac sympathetic activity (10). RRIV showed statistically
insignificantly but appreciable (19%) increase following pranayam
training and this suggests an increase in cardiac parasympathetic
activity (9). On the other hand, there were no significant changes
in these indicators of autonomic status in the control group (Table
I). Hence, our study shows that pranayam training of three
months duration produces a decrease in basal sympathetic tone
and increase in basal parasympathetic activity.
A decrease in sympathetic activity in our pranayam group
is also confirmed by a significant increase in QS2
and QS2I and a significant decrease in LVET and LVETI.
In this connection it is interesting to note that Lewis et al
have found a strong correlation between urinary catecholamine
excretion and QS2I as a dose-dependent shortening of
QS2I in response to intravenously administered positive
ionotropic agents (18). The significant prolongation of PEP and
PEPI in our pranayam group can be attributed to a diminished
rate of left ventricular pressure rise (7). McConahay et al (19)
have reported increase in LVET and a decrease in PEP following
physical exercise and attributed this to increase in sympathetic
activity. Since our finding in group I subjects following pranayam
training are in the opposite direction of those of McConahay et
al (19), we postulate that pranayam training produces decrease
in sympathetic activity. PEP/LVET ratio, which is the single
most useful STI measure of left ventricular performance (7) increased
in both the groups but the increase was more significant in pranayam
group (Table 1). It might be argued that this increase in PEP/LVET
ratio indicates a compromise in myocardial function (8, 20). However,
the, initial value, of PEP/LVET ratio was low in our subjects
and it increased towards the normal range during the three months
of study period. Spitaels et al (21) have reported that the normal
values of PEP/LVET ratio in children is 0.313 ± 0.05 which is
very similar to the value of our group I subjects following pranayam
training. The increase in PEP, PEPI and PEP/LVET ratio in both
the groups (Table 1) can be explained by the fact that PEP increases
as the age advances from infancy to puberty (7, 21). However,
as the increase in these values was more pronounced in the pranayam
group, we suggest that pranayam training promotes normalisation
of' STI values.
In conclusion, the present study shows that three months of
pranayam training, produces a significant decrease in RPP
indicating a decrease in the load on the myocardium This finding
coupled with an overall reduction in oxygen consumption and metabolic
rate as found in earlier studies (1, 2, 17) indicates the potential
benefits pranayam in health and disease. This study also
shows that pranayam training modulates ventricular performance
by altering the cardiac autonomic tone. The changes in ventricular
performance are brought about by increased parasympathetic and
decreased sympathetic activity. Further studies involving larger
sample size and other indicators of cardiac performance may unravel
the underlying mechanism(s) involved in this alteration.
ACKNOWLEDGEMENTS
We gratefully acknowledge the financial support from the Central
Council for Research in Yoga and Naturopathy
(CCRYN), New Delhi.
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