Effect of yoga on short term heart rate variability measure as a stress index in subjunior cyclists: A pilot study

Abstract

Subjunior athletes experience mental stress due to pressure from the coach, teachers and parents for better performance. Stress, if remains for longer period and not managed appropriately can leads to negative physical, mental and cognitive impact on children. The present study was aimed to evaluate the effect of integrated yoga module on heart rate variability measure (HRV) measure as a stress index in subjunior cyclists. Fast furrier transform technique of frequency domain method was used for the analysis of HRV. We have found a significant increase in high frequency (HF) component by 14.64% (P<0.05) and decrease in the low frequency component (LF) of HRV spectrum by 5.52% (P<0.05) and a decrease in LF/HF ratio by 19.63% (P<0.01) in yoga group. In the control group, there was decrease in the HF component and, no significant difference in the LF component of HRV spectrum and LF/HF ratio. The results show that yoga practice decreases sympathetic activity and causes a shift in the autonomic balance towards parasympathetic dominance indicating a reduction in stress. In conclusion, yoga practice helps to reduce stress by optimizing the autonomic functions. So, it is suggested to incorporate yoga module as a regular feature to keep subjunior athletes both mentally and physically fit.

Full text

*Corresponding author : Dr. Satish G Patil, Department of Physiology, BLDE University’s Sri B.M.Patil Medical
College, Bijapur, Karnataka, India; Email: sathupatil@yahoo.co.in; Cell No.: 9986789583
EFFECT OF YOGA ON SHORT TERM HEART RATE VARIABILITY
MEASURE AS A STRESS INDEX IN SUBJUNIOR CYCLISTS :
A PILOT STUDY
SATISH G. PATIL*, LATA M. MULLUR, JYOTI P. KHODNAPUR,
GOPAL B. DHANAKSHIRUR AND MANJUNATHA R. AITHALA
Department of Physiology,
BLDE University’s Sri B. M. Patil Medical College,
Bijapur, Karnataka, India
( Received on September 3, 2012 )
Abstract : Subjunior athletes experience mental stress due to pressure
from the coach, teachers and parents for better performance. Stress, if
remains for longer period and not managed appropriately can leads to
negative physical, mental and cognitive impact on children. The present
study was aimed to evaluate the effect of integrated yoga module on heart
rate variability measure (HRV) measure as a stress index in subjunior
cyclists. Fast furrier transform technique of frequency domain method was
used for the analysis of HRV. We have found a significant increase in high
frequency (HF) component by 14.64% (P<0.05) and decrease in the low
frequency component (LF) of HRV spectrum by 5.52% (P<0.05) and a
decrease in LF/HF ratio by 19.63% (P<0.01) in yoga group. In the control
group, there was decrease in the HF component and, no significant
difference in the LF component of HRV spectrum and LF/HF ratio. The
results show that yoga practice decreases sympathetic activity and causes
a shift in the autonomic balance towards parasympathetic dominance
indicating a reduction in stress. In conclusion, yoga practice helps to reduce
stress by optimizing the autonomic functions. So, it is suggested to
incorporate yoga module as a regular feature to keep subjunior athletes
both mentally and physically fit.
Key words : yoga heart rate variability stress subjunior cyclists
INTRODUCTION
Sports uphold a well-balanced healthy
lifestyle. It imparts both positive and negative
influences on different developmental stages
of children. Children practicing sports
(subjunior athletes) experience dual pressure
from coach demanding good performance and
even from teachers and parents as well for
better academic performance. This makes the
children experience stress manifesting
detrimental effects on their health (1).
Indian J Physiol Pharmacol 2013; 57(2) : 81–86

82 Patil et al Indian J Physiol Pharmacol 2013; 57(2)
Inappropriate management of stress for
longer period leads to negative physical,
mental and cognitive impact on children (1,
2). It also leads to anxiety, depression, poor
memory and lower academic achievement
(3). Studies show that chronic life stress and
diseases are very closely associated (4, 5).
Stress influences the hypothalamus via the
limbic system and causes changes in the
heart rate variability (HRV) through the
autonomic nervous system. Heart rate
variability (HRV) is a non-invasive measure
being used to evaluate the mental stress and
to determine the status of autonomic
nervous system (6).
Stress increases the sympathetic activity
and decreases the activity of parasympathetic
nervous system (7). In a short term HRV
analysis in sub junior cyclists, an increase
in sympathetic activity and decrease in
parasympathetic dominance was observed
indicating stress in these subjects (8). In
addition to the cycling practice, notable
increase in stress levels might be associated
with the busy academic schedule and extra
coaching classes. This might contribute to
eminent mental stress than a physical one
in an individual. These children necessitate
a proper relaxation technique to overcome
inordinate mental stress.
Yoga is an ancient system of life style
having a psycho-somatic-spiritual discipline
that helps to achieve a harmony between
our mind, body and soul. Yoga helps to
manage stress and to reduce anxiety leading
to negative affects and enhances the
positivity and mental Poise (9). Currently
no documented studies depicting role of yoga
on stress in sub junior athletes were
available and hence the present study was
conducted to evaluate the effect of integrated
yoga module on HRV measure as a stress
index in subjunior cyclists.
METHODS
The present study was conducted on 24
healthy subjunior cyclists of Government
school of sports, Bijapur District, Karnataka.
Both males (n=12) and females (n=12) were
recruited for the study. The age of subjects
ranged from 11-13 years. Subjects with LF/
HF ratio > 2; were included for the study.
Subjects on any medication or suffering from
any acute or chronic disease were excluded
from the study. Informed consent was
obtained for participation in the study. The
study was approved by the institutional
ethical committee.
Study design
The subjects were screened and those
with LF/HF ratio > 2; were selected for the
study after thorough examination. The
subjects were randomly divided into study
group (n=12) and control group (n=12) by
using random number table. The study group
was assigned to yoga training by a yoga
instructor for one hour daily in the evening
from 5.30 PM to 6.30PM for four weeks. The
yoga training includes asanas, pranayama
and meditation (10) (Table I). The control
group was assigned to routine practice
for the same duration, under the supervision
of their coach. Two subjects, one from the
yoga group and another from the control
group discontinued the study because they
got selected for the national level
competition. All the recordings were made
twice, before and after four weeks of
intervention.

Indian J Physiol Pharmacol 2013; 57(2) Effect of Yoga on HRV in Cyclists 83
Data acquisition
All the parameters were recorded after
supine rest for 10 minutes in the morning
between 8 am to 10 am at room temperature.
Blood pressure was measured by using the
sphygmomanometer. A 5 minute ECG was
recorded in the standard limb lead II
configuration using a four channel digital
polygraph (Medicaid systems Pvt Ltd,
Chandigarh, India). The recorded data were
visually inspected off-line and only noise free
data were included for analysis. No ectopic
beats were found on offline scrutiny. The
subjects were asked to breathe normally
during the ECG recording.
Data analysis
HRV assessment was done using the HRV
analysis software version 2.0, developed by
the Biomedical Signal Analysis group,
University of Kuopio, Finland (11).
Frequency domain method was used for
analysis of HRV. A non parametric Fast
Furrier Transform (FFT) technique was used
to obtain the Power spectral density of the
RR Series. Total power in the frequency
range (0-0.40Hz) was divided into very low
frequency (VLF: 0-0.04), low frequency
(LF: 0.04-0.15Hz) and high frequency (HF:
0.15-0.40Hz). LF measure reflects both
sympathetic and parasympathetic activity.
HF measure reflects parasympathetic
activity. The LF and HF components were
expressed in normalized units (n.u). LF/HF
ratio was calculated to assess overall
balance between the sympathetic and the
parasympathetic systems. HRV analysis was
done as per the guidelines of a Task force of
the European Society of Cardiology and the
North American Society of Pacing and
Electrophysiology (12). Heart rate (HR) was
calculated from the RR interval obtained
from the ECG recording.
Statistical analysis
The obtained data was expressed in
mean and standard deviation. A student’s
paired ‘t’ test was applied to determine
the statistical significance. Statistical
significance was established at P<0.05.
Data was analyzed using the SPSS
software.
RESULTS
The demographic characteristics of the
subjects in yoga and control group were
shown in Table II. There was no significant
difference between the study and control
group, indicates equal distribution.
Table I : Integrated Yoga module for stress.
Sl.No. Yoga practice Duration
(60 min)
A Starting prayer 1 min
B Breathing practices
1. Hands stretch breathing 02 min
2. Hands in and out breathing 02 min
3. Ankle stretch breathing 02 min
4. Tiger breathing 02 min
C Quick relaxation technique 03 min
D Asana
1. Ardhakati cakrasana
(both sides) 2 min
2. Garudasana 1 min
3. Bhujangasana 1 min
4. Sashankasana 1 min
E Deep relaxation technique 7 min
F Pranayama
1. Nadishudhi 5 min
2. Sitali 2 min
3. Bhramari 3 min
G Meditation
1. Nadanusandhana 15 min
2. Om Meditation 10 min
H Closing prayer 01 min

84 Patil et al Indian J Physiol Pharmacol 2013; 57(2)
There was a significant decrease in the
LF component and an increase in the HF
component of HRV spectrum following a four
weeks of yoga practice. The LF/HF ratio was
also significantly decreased in this group
(Table III).
In the control group, a significant
decrease in the HF component was found,
suggesting a decrease in the parasympathetic
activity. Though not significant, but an
increase in the mean LF and LF/HF ratio
was found in this group (Table IV).
DISCUSSION
HRV is a known prime non-invasive
measure for cardiovascular autonomic
regulation. HRV also provides an opportunity
to study and assess the association between
TABLE II : Demographic Characteristics of subjects
in Yoga and control group (n=22).
Variable Yoga group Control group P-
(n=11) (n=11) value
Sex (Male/Female) 6/5 5/6 —
Age (Years) 11.63±0.67 11.52±0.62 0.29
BMI (kg/m2) 17.37±3.2 18.56±2.6 0.37
Heart Rate (bpm) 81.78±8.43 85.74±9.9 0.111
Systolic BP 107.12±4.83 104.9±4.95 0.331
(mmHg)
Diastolic BP 70.96±4.84 70.15±3.38 0.281
(mmHg)
Pulse Pressure 39.84±2.79 39±1.08 0.29
(mmHg)
MAP (mmHg) 80.71±4.92 81.9± 3.9 0.582
LF/HF ratio 2.7±0.5 2.62±0.49 0.591
Values are expressed in Mean±SD. *P<0.05,
**P<0.01, ***P<0.001.
BMI – Body mass index; MAP – Mean arterial
pressure; LF – Low frequency component
of HRV; HF – High frequency component of
HRV.
TABLE III : Heart rate variability before and after yoga intervention (n=11).
Before After 95% confidence interval t P
Variables yoga yoga value value
Mean±SD Mean±SD Lower Upper
LF (n.u) 72.7±3.47 68.69±4.51 0.417 7.619 2.486 0.032*
HF (n.u) 27.29±3.47 31.3±4.52 –7.619 –0.417 –2.486 0.032*
LF/HF ratio 2.7±0.5 2.17±0.45 0.207 0.846 3.677 0.004**
Values are expressed in Mean±SD. *P<0.05, **P<0.01, ***P<0.001. LF – Low frequency component of
HRV; HF – High frequency component of HRV.
TABLE IV : Heart rate variability at baseline and after four weeks in control group (n=11).
Baseline After 95% confidence interval t P
Variables yoga 4 weeks value value
Mean±SD Mean±SD Lower Upper
LF (n.u) 71.8±3.64 73.78±3.03 –4.987 1.096 –1.425 0.185
HF (n.u) 28.21±3.67 25.24±2.74 0.083 5.861 2.293 0.045*
LF/HF ratio 2.62±0.49 2.94±0.38 –0.733 0.087 –1.751 0.111
Values are expressed in Mean±SD. *P<0.05, **P<0.01, ***P<0.001.
LF – Low frequency component of HRV; HF- High frequency component of HRV.

Indian J Physiol Pharmacol 2013; 57(2) Effect of Yoga on HRV in Cyclists 85
psychological processes and physiological
reactions. It expresses the balance
between the regulation of sympathetic and
parasympathetic nervous system (13). Stress
decreases the HF component of HRV
spectrum and increases the LF component
and LF/HF ratio indicating an increase in
the activity of sympathetic nervous system
(7). This increase in sympathetic activity
is the key factor for development of
cardiovascular disease (14).
In the present study, we have found a
significant increase in HF component by
14.64% (P<0.05), decrease in the LF
component of HRV spectrum by 5.52%
(P<0.05) and decrease in LF/HF ratio by
19.63% (P<0.01) in Yoga group. These
changes suggest a decrease in sympathetic
activity and increase in parasympathetic
dominance. This shift in the autonomic
balance towards the parasympathetic
dominance indicates a reduction in stress.
It has been reported in various studies that
yoga practice will help to bring about a
balance and optimization of autonomic
functions (15-16). In the control group, a
significant decrease in HF component
(P<0.05) and, an increase in mean LF
component of HRV spectrum and LF/HF
ratio was observed suggesting an increase
in sympathetic activity. We have also
observed a significant reduction in HR by
18.13% (P<0.01) in yoga group where as no
significant change was observed in the
control group. A shift in an autonomic
balance towards the parasympathetic
dominance may explain the reduction in HR
in the subjects of yoga group.
The hypothalamic controlled two
important pathways of the stress response
system are: the hypothalamic-pituitary-
adrenocortical axis (HPA) and the
sympathetic-adrenal-medullary (SAM)
system. Cortisol is released in response to
the HPA activation where as SAM system
activation releases catecholamines. These
two hormones help to cope with any form of
stress. But continuous or prolonged stress
interferes in the regulation of physiological
systems by the HPA and SAM systems
resulting in an increased risk for physical
and mental disorders (5). Kamie T et al.,
found a significant decrease in the serum
cortisol level during yoga practice in yoga
instructors (17). Schimdt et al., found a
decrease in urinary excretion of adrenaline,
nor adrenaline, dopamine and aldosterone
during a comprehensive residential three
months of yoga training (18). By this one
can conclude that yoga practice helps in
optimization of autonomic functions and
stress response system thereby enhancing
the coping mechanism for stress.
It may be concluded from the finding
of the study that the yoga intervention
reduces the stress by optimizing the
autonomic functions. So, it is suggested to
incorporate this yoga module as a regular
feature for subjunior athletes to keep them
both mentally and physically fit.
ACKNOWLEDGMENTS
We are thankful to BLDE University,
Karnataka, India for the financial support
to the study. We express sincere thanks to
the coach and head of the Government sports
school, Bijapur, Karnataka, India. We also
thank to all the cyclists who volunteered to
be subjects in this study.

86 Patil et al Indian J Physiol Pharmacol 2013; 57(2)
REFERENCES
1. Romer Gail H. Assessing stress in children: A
literature review.
The Mid-South Educational
Researcher
. 1993; 21: 1–17.
2. Mizoguchi K, Yuzurihara M, Ishige A, Sasnki H,
Chvi DH, Tabira T. Chronic stress induces
impairement of spatial working memory because
of prefrontal Dopaminergic dysfunction.
J
Neurosci
2000; 20: 1568–1574.
3. Farah M, Nobel K, Hurt H. The developing
adolescent brain in socioeconomic context. In D.
Romer Ed.
Adolescent psychology and the
developing brain: Integrating brain and
prevention science.
New York, NY: Oxford
University Press. 2007: 373–387.
4. Joel E D. Psychological stress and cardiovascular
disease.
J Am Coll Cardiol
2008; 51: 1237–
1246.
5. Sheldon Cohen, Denise Janicki-Diverts, Gregory
E Miller. Psychological stress and disease.
JAMA
2007; 298: 1685–1687.
6. Appelhans BM, Lesecken LJ. Heart rate
variability as an index of regulated emotional
responding.
Review of General psychology
2006;
10: 229–2240.
7. Delaney JPA, Brodie DA. Effects of short term
psychological stress on the time and frequency
domains of heart-rate variability.
Percept Mot
Skills
2000; 91: 515–524.
8. Satish G Patil, Lata MM, Khodnapur J, Gopal
BD, Manjunatha Aithala. Short-term heart rate
variability measure in subjunior athletes and
non-athletes. International
Journal of Basic
Medical Sciences
2012; 3: 166–169.
9. Kosuri. M, Sridhar GR. Yoga practice in diabetes
improves physical and psychological outcomes.
Metab Syndr Relat Disord
2009;
7
: 515–517.
10. R Nagarathna, HR Nagendra. Integrated
approach of yoga therapy for positive health. 1
st
edition. Swami Vivekananda yoga prakashana,
Bangalore, India. 2010; 76–168.
11. Niskanen JP, Tarvainen MP, Ranta-aho PO,
Karjalainen PA. Software for advanced HRV
analysis.
Computer Methods and Programs in
Biomedicine
2004; 76:73-81.
12. Task force of the European Society of Cardiology
and the North American Society of Pacing and
Electrophysiology. Heart rate variability:
Standards of measurement, Physiological
interpretation and Clinical use.
Circulation
1996;
93: 1043–1065.
13. Berntson G, Bigger JT Jr, Eckberg DL, et al.
Heart rate variability: Origins, methods and
interpretive caveats.
Psychophysiology
1997; 34:
623–648.
14. Simon C Malpas. Sympathetic nervous system
overactivity and its role in the development of
cardiovascular disease.
Physiol Rev
2010; 90:
513–557.
15. Vempati RP, Telles S. Yoga based guided
relaxation reduces sympathetic activity judged
from baseline levels.
Psychol Rep
2002; 90: 487–
494.
16. Telles S, Nagarathna R, Nagendra HR, Desiraju
T. Physiological changes in sports teachers
following 3 months of training in Yoga.
Indian
J Med Sci
1993; 47: 235–238.
17. Kamei T, Toriumi Y, Kimura H, Ohno, Kumano
H, Kimura K. Decrease in serum cortisol during
yoga exercise is correlated with alpha wave
activation.
Percept Mot Skills
2000; 90: 1027–
1032.
18. Schimdt T, Wijga A, Von Zur Muhlen A, Brabant
G, Wagner TO. Changes in cardiovascular risk
factors and hormones during a comprehensive
residential three month kriya yoga training and
vegetarian nutrition.
Acta Physiol Scand Suppl
1997; 640: 158–162.