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Yoga Relaxation ( savasana ) decreases cardiac sympathovagal balance in hypertensive patients

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OBJECTIVE: Although relaxation is recommended as complementary therapy for hypertension, its post-intervention cardiovascular autonomic effects are unclear. The objective of this research was to investigate the effects of savasana relaxation on cardiovascular autonomic modulation in hypertensive patients. METHODS: This randomized controlled trial was performed at the Hemodynamic Laboratory of the Physical Education School of the University of São Paulo/Brazil. Sixteen hypertensive (6-women) and 14 normotensive patients (6-women) non-obese subjects participated in 2 random sessions: savasana relaxation and control. Patients remained supine for 55 min after interventions. Electrocardiogram, beat-to-beat blood pressure and respiration were acquired during and after interventions for posterior autoregressive spectral analysis of the R-R interval and blood pressure variability. RESULTS: Hypertensive and normotensive patients presented similar cardiac autonomic modulation responses during and after experimental sessions. During relaxation, low frequency and sympathovagal balance were significantly lower in the Relaxation sessions than during supine rest in the Control sessions. Fifteen minutes after interventions, low frequency and sympathovagal balance were still lower in Relaxation than in Control, and remained lower for 35 min; at 55 min, the variables were similar between sessions. Systolic blood pressure variability did not differ among sessions. CONCLUSIONS: Savasana Relaxation decreases cardiac sympathetic autonomic modulation after its performance in hypertensive patients; this reduction lasts at least 35 minutes and is not blunted in hypertensive patients when compared to normotensive controls. Thus, savasana relaxation has positive effects on cardiac autonomic modulation of hypertensive patients, and may be included as a strategy for the non-drug treatment of hypertension.
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ORIGINAL RESEARCH
Yoga Relaxation (savasana) decreases cardiac
sympathovagal balance in hypertensive patients
Danilo F Santaella,
I
Geraldo Lorenzi-Filho,
II
Marcos R Rodrigues,
I
Taı
´s Tinucci,
III
Ana Paula Malinauskas,
IV
De
´cio Mion-Ju
´nior,
V
Nicola Montano,
VI,VII
Cla
´udia LM Forjaz
III
I
Sports Center of the University of Sa
˜o Paulo – Brazil
II
Sleep Apnea Laboratory of the Pneumology Discipline of the Medical School of the University of
Sa
˜o Paulo – Brazil
III
Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sa
˜o Paulo, Brazil
IV
Department of Physical
Therapy, Federal University of Rio Grande do Norte – Brazil
V
Hypertension Unity, General Hospital, University of Sa
˜o Paulo – Brazil
VI
Department of
Biomedical Clinical Sciences, University of Milan, Division of Medicine and Pathophysiology, Sacco Hospital – Milano Italy
VII
ICRC-Department of
Cardiovascular Diseases, St. Anne’s University Hospital Brno Czech Republic
OBJECTIVE: Although relaxation is recommended as complementary therapy for hypertension, its post-
intervention cardiovascular autonomic effects are unclear. The objective of this research was to investigate the
effects of savasana relaxation on cardiovascular autonomic modulation in hypertensive patients.
METHODS: This randomized controlled trial was performed at the Hemodynamic Laboratory of the Physical
Education School of the University of Sa
˜o Paulo/Brazil. Sixteen hypertensive (6-women) and 14 normotensive
patients (6-women) non-obese subjects participated in 2 random sessions: savasana relaxation and control.
Patients remained supine for 55 min after interventions. Electrocardiogram, beat-to-beat blood pressure and
respiration were acquired during and after interventions for posterior autoregressive spectral analysis of the R-R
interval and blood pressure variability.
RESULTS: Hypertensive and normotensive patients presented similar cardiac autonomic modulation responses
during and after experimental sessions. During relaxation, low frequency and sympathovagal balance were
significantly lower in the Relaxation sessions than during supine rest in the Control sessions. Fifteen minutes after
interventions, low frequency and sympathovagal balance were still lower in Relaxation than in Control, and
remained lower for 35 min; at 55 min, the variables were similar between sessions. Systolic blood pressure
variability did not differ among sessions.
CONCLUSIONS: Savasana Relaxation decreases cardiac sympathetic autonomic modulation after its performance
in hypertensive patients; this reduction lasts at least 35 minutes and is not blunted in hypertensive patients when
compared to normotensive controls. Thus, savasana relaxation has positive effects on cardiac autonomic
modulation of hypertensive patients, and may be included as a strategy for the non-drug treatment of
hypertension.
KEYWORDS: Heart rate variability; Hatha Yoga; Hypertension.
Santaella DF, Lorenzi-Filho G, Rodrigues MR, Tinucci T, Malinauskas AP, Mion-Ju
´nior D, Montano N, Forjaz CLM. Yoga Relaxation (savasana)
decreases cardiac sympathovagal balance in hypertensive patients. MEDICALEXPRESS. 2014 Oct;1(5):233-238.
Received for publication on May 27 2014; First review completed on May 21 2014; Accepted for publication on July 3 2014
E-mail: danyoga@usp.br
BINTRODUCTION
Hypertension is a highly prevalent disease, afflicting 40%
of the American population.
1
It is directly related to acute
cardiovascular events, and closely related to end-organ
damage.
2
Furthermore, hypertension is related to an
autonomic dysfunction, with noted augmented sympathetic
and decreased vagal modulation to the heart.
1,3,4
When regularly performed, relaxation decreases blood
pressure
5,6,7,8
sympathetic autonomic modulation to the
heart
9
and sympathetic reactivity,
10
being therefore rec-
ommended as partof the non-drug treatment of hypertension
1
and for maintaining a good and healthy life style.
11
However,
the duration of this acute cardiac autonomic modulation
response to relaxation has not been investigated; neither has
the possibility that hypertensive patients may be less prone to a
decrease in sympathetic and to an increase in parasympathetic
heart modulation than normotensive people.
Spectral analysis of heart rate variabilityhas become a useful
non-invasive tool to investigate sympathovagal balance to the
heart in many circumstances.
12
Studies investigating heart rate
variability after relaxation showed a parasympathetic pre-
dominance in healthy adults
13
and in post cardiac arrest
patients.
14
Savasana is an important part of Hatha Yoga
relaxation practice. To our knowledge, there is no study
addressing the influences of savasana on sympathovagal
balance of hypertensive subjects. Thus, this aspect still needs
DOI: 10.5935/MedicalExpress.2014.05.04
Copyright q2014 MEDICALEXPRESS. This is an open access article distributed under the terms of the creative commons attribution
Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution,
and reproduction in any medium, provided the original work is properly cited.
233
further investigation, especially in populations which may
present cardiac sympathovagal dysfunction.
This paper addresses the following hypothesis: that
savasana relaxation may decrease cardiac sympathovagal
balance in the post-intervention period in hypertensive
patients; that this decrease has a measurable duration; and
that this decrease of the cardiac sympathetic modulation
may be impaired in hypertensive subjects.
Our results show that after savasana relaxation, hyperten-
sive patients had a decrease of cardiac sympathovagal
balance similar to normotensive controls, and this decrease
was present until 35 minutes after intervention.
BMATERIALS AND METHODS
Subjects
Sixteen essential stage I hypertensive (HT- 6 women), and
14 normotensive control (NT- 6 women) non-obese patients
volunteered. All patients signed a written consent to
participate in the study, which was approved by the Ethics
Committee of the Heart Institute and by the Ethics
Committee of Hospital das Clı
´nicas, Faculty of Medicine,
University of Sa
˜o Paulo, Brazil.
Volunteers had their blood pressure measured during two
visits to the laboratory. Inclusion criteria were: normotension
(accepted if the averages of 3 consecutive measurements
were bellow 130 and 85 mmHg for systolic and diastolic
blood pressures, respectively) stage I hypertension (averages
of 3 consecutive measurements were equal to or higher than
140 and 90 mmHg and below 160 and 100mmHg), and body
mass index (BMI) lower than 30 kg/m.
2
Hypertensive
patients had their medication washed-out 30 days prior to
the experiment and replaced by placebo. None of the
volunteers were enrolled in any regular exercise program, or
were acquainted with the practice of savasana relaxation.
In order to establish group pairing related to physical
conditioning, peak oxygen uptake (VO
2
peak) was measured
directly by a metabolic cart (Medical Graphics Corporation
CAD/NET-2001) during maximal progressive exercise test
performed on a cycle ergometer (MIJNHARDT-Ken III)
using a protocol of 30 W-increments every 3 min till
exhaustion. Heart rate (HR) was continuously monitored
by electrocardiography (ECGTECNOLO
´GICA DO BRA-
SILSM300). Blood pressure was measured (auscultatory
method) at the end of each stage. Tests were interrupted due
to physical fatigue, systolic blood pressure exceeding
250 mmHg, diastolic blood pressure greater than
115 mmHg or abnormalities in the electrocardiogram.
15
Measurements during experimental sessions.
R-R Interval. Electrocardiographic signal was continuously
monitored by ECG (TECNOLO
´GICA ELETRO
ˆNICA DO
BRASIL-SM300).
Blood pressure. Blood pressure was measured by finger
photoplethismography on a beat-to-beat basis using a non-
invasive finger monitor (OHMEDA-FINAPRES) on the
middle finger of the non-dominant arm.
Respiration. Respiratory movements were monitored by a
respiratory belt (UFIPneumotrace II) positioned around the
subject’s thorax.
Autonomic modulation. Electrocardiographic, respiratory, and
blood pressure were acquired in a microcomputer through
the Windaq software - sampling rate of 500 Hz/channel.
Sympathetic and parasympathetic cardiac modulations were
obtained by spectral analysis of the R-R interval variability,
and sympathetic vasomotor modulation was investigated by
spectral analysis of systolic blood pressure variability
through autoregressive algorithms. On stationary segments
of time series, autoregressive parameters were estimated via
Levinson-Durbin recursion, and the order of the model
chosen according to Akaike’s criterion. This procedure
permitted us to automatically quantify the center frequency
power of each relevant component of the spectrum in
absolute as well as normalized units (nu). The normalization
procedure was performed by (i) dividing the power of the
low-frequency component (LF-0.04-0.15 Hz) or high-fre-
quency component (HF-0.15-0.5 Hz) by the total spectral
power; (ii) from this, the power of the very low frequency
(VLF –0.00-0.04 Hz) component was subtracted. The result
was multiplied by 100.
16
Intervention.
Relaxation. Relaxation sessions lasted 20 min, based on the
Yoga technique called savasana.
17
During this intervention,
volunteers remained supine and tried to develop a conscious
detachment from the external environment. To do so, they
listened to a recording with 10 min of conducted relaxation
followed by 10 min of silence.
Experimental Protocol.All patients were submitted to 2
experimental sessions in a random order, with a minimum
4-day interval. Immediately after arriving at the laboratory,
patients emptied their bladders and were prepared
for acquisitions. Afterwards, one of the following
interventions took place: savasana relaxation (R 20 min)
or control (C 20 min of supine rest). ECG and respiration
were recorded continuously for 10 min during R and C. After
interventions, patients rested supine during 55 min, which
was considered the post-intervention period (P). During this
period, ECG, blood pressure, and respiratory signals were
continuously recorded during the intervals 15– 25 min (P15),
35 –45 min (P35), and 50– 55 min (P55).
Statistical Analysis.Data were submitted to a two
(during interventions) or three-way (after interventions)
analysis of variance for repeated measures, establishing
groups (normotensive and hypertensive) as independent
factors, and experimental sessions (R and C) and stages
(post-intervention - P15, P35, P55) as dependent ones.
Newman-Keuls test was used for post-hoc comparisons and
a level of P ,0.05 was accepted as significant. Data are
presented as means ^SEM. Results were analyzed with
SPSS software v 18.0.
BRESULTS
Forty six patients volunteered: 24 hypertensive and 22
normotensive patients. Eight hypertensive patients were
excluded: six due to stage II hypertension and systolic and/
or diastolic values higher than 220/120 mmHg during rest
before the cardiopulmonary exercise test; two due to the use
of other medications or presence of atrial fibrillation. Eight
normotensive patients were excluded for presenting more
than 5 extra-systoles/min (n ¼3), or for failing to attend all
experimental sessions (n ¼5). Thus, 30 patients finished the
study, 16 hypertensive (6 women), and 14 normotensive
(5 women) ones, as shown in Figure 1.
Physical and cardiovascular characteristics of the patients
(normotensive vs. hypertensive patients) are shown in
Yoga relaxation in hypertensive patients
Santaella DF, et al.
MEDICALEXPRESS 2014 October;1(5):233-238
234
Table 1. Groups were statistically similar for age, body mass
index, heart rate, and VO
2
peak. Hypertensive patients had
significantly higher systolic and diastolic blood pressures.
Responses during savasana relaxation
Heart rate variability and respiration during savasana
relaxation and control sessions are shown in Table 2. During
savasana, respiratory frequency was significantly higher in
hypertensive vs. normotensive patients. However, in both
groups of patients, respiratory frequency during savasana
was similar to their respective basal levels. Autonomic
modulation was similar between normotensive and hyper-
tensive groups during interventions. During Relaxation,
total variance was not altered, but LF
nu
and LF/HF were
significantly lower (p ,0.05), while RR interval and HF
nu
were significantly higher than in Control (p ,0.05).
Responses after savasana relaxation
Mean data for the post-intervention period are summarized
in Table 3, and the most important variables are shown in
Figure 2. Respiratory frequency was significantly lower in the
normotensive than in the hypertensive group during all of the
post intervention period in all sessions (p ,0.05). Respiratory
frequencies after interventions were similar between exper-
imental sessions. Hypertensive and normotensive patients
presented similar autonomic responses after interventions.
Thus, independent of group, mean RR interval was signifi-
cantly lower after savasana versus control at all of the post-
intervention periods (p ,0.05), while total variance did not
change between experimental sessions and measurement
points. At P15, LF
nu
and LF/HF were significantly lower and
HF
nu
was significantly higher after savasana vs. control
(p ,0.05). At P35, LF
nu
(p ,0.05) and LF/HF (p ,0.05)
were significantly lower and HF
nu
was significantly higher
during savasana vs. control (p ,0.05). At minute P55 after the
interventions, there was no statistical difference in any
autonomic variable between experimental sessions.
As expected, systolic blood pressure was significantly higher
in hypertensive than in normotensive patients (p ,0.05).
Independent of the post-intervention moment, systolic blood
pressure was similar between sessions for savasana and control
(p .0.05) in both groups. Total variance and LF component of
the systolic blood pressure variability were similar among the
sessions at all the post-intervention moments.
BDISCUSSION
The main findings of the present paper are: 1) savasana
relaxation caused a reduction of cardiac sympathovagal
balance; 2) this shift of the sympathovagal balance toward a
higher parasympathetic modulation was similar between
hypertensive and normotensive patients; 3) the autonomic
cardiac modulation influence of savasana relaxation lasted for
at least 35 minutes after it was performed; 4) sympathetic
vasomotor tone was not influenced by savasana relaxation.
These results confirm the study hypothesis, since savasana
relaxation decreased cardiac sympathovagal balance by
increasing parasympathetic cardiac modulation and
decreasing cardiac sympathetic modulation similarly in
hypertensive and normotensive patients. This effect is not
impaired in hypertensive patients. Furthermore, the dur-
ation of this decrease in sympathetic cardiac modulation
Table 1 - Physical and cardiovascular characteristics of
normotensive individuals (NT) vs. patients (HT).
NT HT
Age, years 39 ^243^1
BMI, kg/m
2
25.3 ^0.4 26.7 ^0.6
Heart rate, bpm 74 ^377^2
Systolic Blood Pressure, mmHg 120 ^1
a
144 ^2
Dyastolic Blood Pressure, mmHg 74 ^1
a
96 ^1
VO
2
peak, ml.kg
21
.min
21
33.7 ^1.6 30.5 ^1.7
Values are means ^SE. BMI Body mass index. a HT (p ,0.05).
Figure 1 - Subjects distribution. Forty six subjects volunteered: 24 hypertensive, and 22 normotensive subjects. Eight subjects of each
group were excluded since they did not meet inclusion criteria; thus, 16 hypertensive, and 14 normotensive subjects were included in this
research.
Table 2 - Autonomic data evaluated during savasana
relaxation (R), and control (C) sessions in the
normotensive controls (NT) and hypertensive patients (HT).
CR
NT HT NT HT
RF 0.26 ^0.03
b
0.34 ^0.07 0.27 ^0.04
b
0.32 ^0.06
RR 922 ^74 919 ^34 952 ^38
a
913 ^25
a
TV
RR
2716 ^715 1910 ^406 2698 ^1175 1589 ^234
LF
RR
,nu 59^567^351^5
a
50 ^3
a
HF
RR
,nu 38^529^343^5
a
45 ^4
a
LF/HF
RR
2.7 ^0.7 2.7 ^0.4 1.2 ^0.3
a
1.3 ^0.2
a
Values are means ^SE. RF – Respiratory Frequency; RR – R-R interval; TV –
Total variance; LF – Low frequency; HF – High frequency; LF/HF
Sympathovagal balance. a C(p,0.05); b HT (p ,0.05).
MEDICALEXPRESS 2014 October;1(5):233-238 Yoga relaxation in hypertensive patients
Santaella DF, et al.
235
could be measured. It lasted at least 35 minutes. Thus, it is
possible to state that savasana relaxation may have clinical
importance for the non-drug treatment of hypertension.
In accordance with the literature,
5,6
relaxation led to a
decrease in LF
nu
and to an increase in HF
nu
during its
execution, indicating a shift of the sympathovagal balance
towards the parasympathetic branch of cardiac autonomic
modulation. Furthermore, savasana relaxation also led to a
decrease in sympathetic and to an increase in parasympa-
thetic cardiac modulation after its execution, because 35 min
after relaxation, HF
nu
was higher and LF
nu
and LF/HF were
lower than in C. Because there was no difference for
autonomic modulation between groups either during, or
after intervention, the hypothesis that hypertensive patients
might have impaired autonomic response to relaxation is
refuted. During relaxation, LF/HF was already below C and
remained low until 35 min of the post-intervention period.
However, this status progressively changed throughout this
period, since sympathovagal balance returned to control
levels at 55 min of post-intervention. Thus, it is possible to
state that the duration of the effect is at least 35 minutes.
The mechanisms by which savasana relaxation may have
decreased sympathovagal balance after its execution is out of
the scope of this study. However, some speculation may be
Table 3 - Autonomic data evaluated from 15 to 25 min (P15), from 35 to 45min (P35), and 50 to 55 min (P55) after the
intervention in control (C) and relaxation (R), in the normotensive controls (panel A) and hypertensive (panel B) groups.
A – NT Control Savasana Relaxation
P15 P35 P55 P15 P35 P55
RF, Hz 0.27 ^0.01
b
0.28 ^0.01
b
0.29 ^0.01
b
0.27 ^0.01
b
0.28 ^0.01
b
0.29 ^0.01
b
RR, ms 1038 ^36 1018 ^38 1008 ^38 964 ^40
a
950 ^40
a
945 ^36
a
TV
RR
,ms
2
4009 ^948 3160 ^712 3929 ^773 3876 ^1839 3814 ^1219 2955 ^1024
LF
RR
,nu 61^466^357^650^6
ad
52 ^5
a
55 ^6
HF
RR
,nu 31^431^438^541^5
ad
41 ^6
a
40 ^6
LF/HF
RR
3.0 ^0.8 2.8 ^0.6 2.4 ^0.5 2.2 ^0.6
ad
2.3 ^0.7
a
2.2 ^0.5
SBP, mmHg 111 ^5
b
117 ^5
b
116 ^5
b
109 ^3
b
111 ^4
b
116 ^4
b
TV
SBP
, mmHg
2
31 ^624^325^430^442^10 35 ^8
LF
SBP
, mmHg
2
19 ^713^318^512^317^10 26 ^8
B – HT Control Savasana Relaxat ion
P15 P35 P55 P15 P35 P55
RF, Hz 0.35 ^0.01 0.33 ^0.01 0.33 ^0.01 0.32 ^0.01 0.32 ^0.02 0.32 ^0.01
RR, ms 948 ^29 944 ^32 968 ^32 937 ^28
a
934 ^26
a
926 ^24
a
TV
RR
,ms
2
2793 ^519 3026 ^618 2746 ^611 2960 ^937 2719 ^607 2110 ^543
LF
RR
,nu 68^368^258^446^4
a
48 ^3
a
54 ^5
HF
RR
,nu 27^327^235^446^4
a
45 ^3
a
40 ^5
LF/HF
RR
3.3 ^0.5 2.8 ^0.3 2.4 ^0.5 1.2 ^0.2
a
1.3 ^0.2
a
2.3 ^0.5
SBP, mmHg 130 ^4 132 ^4 138 ^4 134 ^4130^4 138 ^5
TV
SBP
, mmHg
2
35 ^542^124^744^835^628^5
LF
SBP
, mmHg
2
19 ^410^211^324^715^612^4
Values are means ^SE. RF respiratory frequency (Hz); RR R-R interval (msec); TV total variance (msec
2
); LF – low frequency component; HF high
frequency component; LF/HF sympathovagal balance; SBP systolic blood pressure (mmHg). a C(p,0.05); b HT (p ,0.05).
Figure 2 - RR interval, sympathovagal balance of RR interval variability (LF/HF
RR
), systolic blood pressure (SBP) and low frequency
component of systolic blood pressure (LF
SBP
) measured at 15 (P15), 35 (P35), and 55 (P55) minutes of post-intervention period on the two
experimental sessions: relaxation (R) and control (C). Data from both groups (normotensive and hypertensive patients) were combined.
Yoga relaxation in hypertensive patients
Santaella DF, et al.
MEDICALEXPRESS 2014 October;1(5):233-238
236
pertinent. One could state that the decrease in sympathova-
gal modulation during relaxation and after intervention
might be related to changes in respiratory frequency, which
markedly influences cardiac autonomic modulation.
18
However, as respiratory frequency was not altered by
relaxation, and was similar after intervention, this possibility
is refuted. The effect of relaxation, thus, could be related to
its effects on the central regulator of sympathetic and
parasympathetic nucleus.
19
Nevertheless, further studies are
necessary to investigate this issue.
Another possible mechanism for cardiovascular changes
after intervention might have been altered vasomotortone, as is
observed after physical exercise.
10,20
In fact, relaxation led to
hypotension, as systolic blood pressure was lower after
Relaxation than after Control. Previous studies,
21,22
employing
microneurography suggested that the post-exercise blood
pressure decrease is due to a decrease in peripheral
sympathetic activity when recovery is conducted in a supine
position. However, in the present study, total variance and LF
component of systolic blood pressure variability, which may
represent sympathetic vasomotor activity,
12
were not
decreased after relaxation. These different results may be
related to methodological aspects:1) the kind of measurement,
i.e. microneurography measures sympathetic traffic to a
specific nerve, while blood pressure variability evaluates
vasomotor response to sympathetic activity in the whole body,
and 2) the timing, i.e. previous studies measured sympathetic
activity 60 min after exercise, while in the present study
measurements were taken earlier, and did not address exercise
conditions. Thus, it seems pertinent to state that mechanisms
responsible forcardiovascular autonomic modulation effects of
savasana relaxation are different from those of physical exercise.
Since autonomic dysfunction is associated with a worse
cardiovascular prognosis, and hypertensive patients may
have increased cardiac sympathovagal balance,
3,4
the results
of this study may have clinical importance for hypertensive
patients. The investigated intervention (savasana relaxation)
decreased sympathovagal balance after its execution, and
this reduction was not impaired by hypertension. Thus,
these findings strengthen the recommendation of relaxation
as part of the non-pharmacological treatment of hyperten-
sion, performed alone or in association.
BCONCLUSION
In conclusion, savasana relaxation decreases cardiac sym-
pathovagal balance after its execution in hypertensive patients.
This reduction lasts at least 35 minutes, and is not impaired in
hypertensive when compared to normotensives patients. Thus,
savasana relaxation has positive effects on cardiac autonomic
modulation of hypertensive patients, and may be included as a
strategy for the non-drug treatment of hypertension.
Limitations
Both men and women were studied and, thus, differences
between genders were not addressed. Results are limited to
stage I hypertensive and healthy normotensive patients.
Variables were not measured before interventions, which
would have allowed a specific description of what happened
from pre to post-intervention periods. However, as sessions
were randomly ordered, it is reasonable to expect that pre-
intervention values were similar and thus comparisons
between sessions at the post-intervention period reflect
differences in behaviors between pre and post periods.
Spectral analysis of cardiovascular variability must always
be faced as a tool to access cardiovascular autonomic
modulation and not total autonomic activity.
The different groups were expected to present different
cardiac autonomic modulations at rest, with a greater
sympathetic modulation in hypertensive patients,
3,4
but this
was not corroborated by our results. One possible reason for
this is the hypertension stage of the sample: because patients
had to be washed out of medication 1 month prior to the
protocol, only stage I hypertensive patients without
complications entered the study. Most of the literature
addresses stage II hypertensive patients.
BSUMMARY
Briefly, savasana relaxation decreases cardiac sympathovagal
balance(LF/HF ratio),increasingparasympathetic modulation
to the heart in hypertensive patients, without disadvantages
when compared to normotensives. This effect lasts at least
35 minutes. Its mechanisms require further investigation.
BACKNOWLEDGEMENTS
We would like to thank Alberto Porta, Ph.D. for providing the software (LA,
version 8.3 – Brazil) for spectral analysis, developed in the University of
Milan, Italy. We gratefully acknowledge the volunteers of this study. Financial
support: Fundaca
˜o de Amparo a
`Pesquisa do Estado de Sa
˜o Paulo - FAPESP
[99/12278-4]; and Conselho Nacional de Desenvolvimento Cientı
´fico e
Tecnolo
´gico - CNPq [46133900-5].
BAUTHOR DISCLOSURE STATEMENT
No competing financial interests exist.
BRESUMO
OBJETIVO: Embora o relaxamento seja recomendado como terapia
complementar no tratamento da hipertensa
˜o, seus efeitos na modulaca
˜o
autono
ˆmica cardiovascular ainda na
˜o esta
˜o claros. O objetivo desse trabalho
foi investigar os efeitos do relaxamento na modulaca
˜o autono
ˆmica cardı
´aca de
indivı
´duos hipertensos.
ME
´TODOS: Este estudo aleatorizado e controlado foi realizado no
Laborato
´rio de Hemodina
ˆmica da Escola de Educaca
˜oFı
´sica e Esporte da
Universidade de Sa
˜o Paulo/Brasil. Dezesseis hipertensos (6-mulheres) e 14
normotensos controle (6-mulheres) na
˜o-obesos participaram de 2 sesso
˜es
aleato
´rias: relaxamento (R) e controle (C). Os participantes permaneceram
supinos por 55 minutos apo
´s as intervenco
˜es. Eletrocardiograma, pressa
˜o
arterial batimento a batimento, e respiraca
˜o foram adquiridos durante e apo
´s
as intervenco
˜es para a posterior ana
´lise espectral autorregressiva das
variabilidades do intervalo R-R e da pressa
˜o arterial.
RESULTADOS: Hipertensos e normotensos apresentaram respostas semel-
hantes de modulaca
˜o autono
ˆmica cardı
´aca durante e apo
´s as sesso
˜es
experimentais. Durante o relaxamento, a baixa freque
ˆncia e o equilı
´brio
simpatovagal da variabilidade da freque
ˆncia cardı
´acaestavam significantemente
mais baixas no R do que no repouso supino em C. Quinze minutos apo
´sa
intervenca
˜o a baixa freque
ˆncia e o equilı
´brio simpatovagal ainda estavam
inferioresem R do que em C, o que ocorreu tambe
´m nos 35 minutos,mas na
˜oaos
55 minutos. A variabilidade da pressa
˜o arterial foi semelhante entre as sesso
˜es.
CONCLUSA
˜O: O relaxamento savasana reduz a modulaca
˜oautono
ˆmica
simpa
´tica cardı
´aca de hipertensos; essa reduca
˜o perdura por pelo menos 35
minutos apo
´sote
´rmino do relaxamento e na
˜oe
´prejudicada nos hipertensos
quando comparados com normotensos. Dessa forma, o relaxamento savasana
tem efeitos positivos na modulaca
˜oautono
ˆmica cardı
´aca de hipertensos e pode
ser incluı
´do como estrate
´gia para o tratamento na
˜o-medicamentoso da
hipertensa
˜oarterial.
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Yoga relaxation in hypertensive patients
Santaella DF, et al.
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238
... The intervention group was subjected to 4 weeks' Yoga training by a certified Yoga teacher as per Table 1. Following four Pranayams, Suryanamaskar [5] (SN) and Shavasan [6] were included in the training: ...
... The observed cardiovascular changes may also be due to the Shavasan which is reported to reduce cardiac sympathetic modulation. [6] Yoga practices, including relaxation (such as Shavasan), improves autonomic modulation and enhances vagal dominance. [19] Hence, Shavasan may be included in the non-pharmacological management of hypertension. ...
... However, the period of this acute cardiac autonomic modulation reaction to rest has now no longer been investigated; neither has the opportunity that hypertensive sufferers can be much less susceptible to a lower in sympathetic and to an increase in parasympathetic coronary heart modulation than normotensive humans. [20] The significance of stress in the development of hypertension is debatable. [11,12] However, there is evidence that controlling some types of stress can be extremely beneficial in the treatment and prevention of essential hypertension. ...
Article
Full-text available
Objective: Hypertension is more common in cities than it is in rural regions. Indo-Asian people are among the populations with the highest risk of cardiovascular disease in the world. Stress has become a part of our life due to hectic lifestyle that we have and so is the lifestyle disorders like hypertension. The aim of this study is to find the correlation between blood pressure and perceived stress and how they are related. Method: In this correlation study 30 individuals were selected. Basic demographic data was collected and were asked to fill up the Perceived stress scale. Blood pressure was measured at the brachial artery three times and average of the three was taken. To study the relation between stress score and BP, correlation was done. As data were not normally distributed, Spearman correlation test was done (P < 0.001). Results: According to the analysis done, PSS shows moderate correlation with SBP while DBP shows weak correlation with r values 0.47 and 0.202 respectively and p values 0.806 and 0.283 respectively. Conclusion: Stress is significantly related to hypertension and is an independent risk factor for hypertension.
... J. Sport Tourism 2020, 27(4), [29][30][31][32][33][34][35] may stem from a longer resting phase as well as using yoga nidra relaxation instead of supine resting. Santaella et al. [47] compared the 20-minute yoga relaxation (savasana) with resting supine position both in hypertensive patients and normotensive individuals, and reported yoga relaxation to be more effective for enhanced HRV parameters (RR intervals, LFnu, HFnu, and LF/HF). Similar changes in LFnu, HFnu and LF/HF parameters were observed even after 10-minute yoga-based relaxation when compared with supine rest [48]. ...
Article
Full-text available
Introduction. This study purposed to examine energy expenditure (EE) of one-hour hatha yoga (HY) practice and to compare changes in heart rate variability (HRV) during and right after HY practice. Material and methods . A total of ten experienced female HY practitioners participated in the study voluntarily. Daily EE on a weekday and during a one-hour HY session was measured using a metabolic holter. The ECG holter was applied to record HRV variables 5 minutes before, during, 5 minutes after and 10 minutes after the one-hour HY session. The HY session included HY asanas for the first 55 minutes and meditation during the last 5 minutes. Results. Participants showed 2201.40 kcal of total EE, and 421.70 kcal of active EE during the weekday. Active EE was 109.70 kcal (26% of daily active EE) during the one-hour HY session, and the mean MET was recorded as 2.57. HRV measurements showed crucial changes. Increased sympathetic activity observed in SDNN, RMSSD, NN50, pNN50, LF/HF, and HF did not reach the initial level after 15 minutes of total recovery time. Conclusions. One hour of HY practice provided moderate EE. Moreover, 10 minutes of supine rest in addition to 5 minutes of the meditation phase of HY practice is not seen as completely effective in improving parasympathetic activity and returning the practitioners to their initial level. Extending the meditation phase at the end of the HY session by more than 10 minutes and measuring the recovery process of HRV could add more detailed results to the literature.
... [26] Another study of 60 healthy individuals showed that a 12-week alternate nostril breathing exercise program showed a significant decrease in the mean SBP of the participants. [27] The results of this study showed that the patients who participated in the silent sitting session showed a decrease of approximately 3 and 5 mmHg in the SBP and DBP, respectively, whereas the patients who performed the alternate nostril breathing exercise showed a decrease of about 4 mmHg in both SBP and DBP measured at the end of the second week ( Table 3). Results of intergroup evaluation of the decrease in BP showed a significant decrease in the SBP of patients who performed the breathing exercises, which is consistent with the findings reported previous (p<0.05) ...
... Compared to resting baseline, a pattern of parasympathetic reactivation (as indicated by slight increase in HF [ms2] as well as HF [nu]), along with significant cardio deaccelaration was observed during shavasana. Santaella et al. [32] and Vempati and Tellis [33] in their study where they have seen the shavasana and yoga-based guided relaxation on autonomic modulation also observed similar results. A similar pattern was also observed during the recovery phase of exercise by Perini et al. [34] The initial cardio deaccelaration can be contributed to fast phase of parasympathetic reactivation due to abrupt removal of central command (Pecanha et al.), [35] together with abolished feedback from muscle mechanoreceptors, and delayed withdrawal of sympathetic system (Pichon et al.), [36] the increment in LF (ms2) may be indicative of resetting of baroreflex function in the supine posture. ...
Article
Full-text available
Objectives Health benefits of aerobic exercises and Yogaasana (Yoga Postures) in lifestyle diseases are well known. There are pointers that these health benefits may be mediated through cardiac autonomic modulation. “Acute State effects” of autonomic modulation during aerobic exercise is fairly established; however there is relative dearth of information about it during Yogasana (Yoga Postures). The purpose of present study is to explore “Acute State Effect” of cardiac autonomic modulations during Yogasana (postures) and mild aerobic exercise (cycling) using heart rate variability (HRV) a cardiac autonomic marker in Yoga naïve volunteers. Materials and Methods Thirty consenting volunteers between eighteen to twenty five years, of both genders performed test protocol comprised of four blocks of modified yoga postures, one block of cycling each of five minute duration and a block of supine rest that served as baseline. High sampled ECG (1 KHz) was recorded during protocol for HRV analysis. Friedman test for multiple blocks comparison and Wilcoxon signed rank test for pair wise comparison was employed. P < 0.05 considered as significant. Results Multiple block comparison of HRV indices ( P < 0.0001) and for breathing rate ( P < 0.0004) were highly significant. Compared to resting baseline a pattern of vagal withdrawal (decrease in HF nu) with increment in average heart rate was observed during modified yogasanas and cycling. Shavasana showed pattern of parasympathetic reactivation with decrement in average heart rate. Conclusion The pattern of autonomic modulation in Yoga naïve performing modified yogasanas was similar to mild intensity cycling. Shavasana showed pattern of post exercise recovery.
... These results are in line with prior researches. Santaella et al., in their study [32], showed that savasana-(relaxation) could be used as a strategy to treat hypertension, because it has positive effects on cardiac autonomic modulation of patients suffering from hypertension. Thomas also showed that a combination of soft music and relaxation techniques reduced anxiety and stress [29]. ...
Article
Full-text available
Abstract In this paper we present an empirical application of our tri-transactional theory of stress [1]. According to this mathematical numerical model, the perceived stress intensity generated after encountering a stimulus (positive or negative) depends not only on this latter’s objective perceived intensity (ST), but also on the perceived previous state of stress (PSS) that a person possessed before facing the stimulus. Its resulting value is the combination of PSS and ST, which is described in the model by the formula (S = PSS + ST) [1]. The main objective of the present study is to empirically demonstrate that PSS is obligatory to take into account in the assessment of an individual state of stress. For this, we examined the combination by testing 5 different hypotheses that: 1) the value of S would simultaneously be different than PSS and STA, where STA (ST of an activity) is the objective perceived stress intensity of an activity (set of stimuli), 2) a negative activity would have a negative effect on PSS, 3) a positive activity would have a positive effect on PSS, 4) S would be associated with PSS, 5) the value of S would depend on PSS and STA. Two different activities, relaxation (savasana accompanied with music) and mental arithmetic (serial subtractions test), were used in the experiment that generated positive and negative stimuli respectively. The secondary objectives were to examine the effect of the 2 activities on gender and age and to check out if there were mutual effects between partial stresses that make up the values of PSS, STA and S. From a voluntary non-probability sample of 131 participants we collected 131 measures. Each measure included the values of PSS, STA and S, each one is composed of 3 different partial stresses (emotional, mental and physical). For statistical analyses, we used Wilcoxon signed rank test to compare between S and PSS and between S and STA, Rho Spearman to check the relationships between partial stresses (emotional, mental, and physical), total stresses (TS, TPSS and TSTA) and their positive and negative components (PS, NS). Mann-Whitney and Kruskal-Wallis tests were used to check if the results depended on gender and age respectively. Multiple linear regression was conducted to check the relationship between the dependent variable S and the independent variables PSS and STA. The results have effectively shown that the 5 hypotheses were confirmed in terms of total, positive and negative stresses. The 2 activities, relaxation and mental arithmetic, have positive and negative effects on PSS and its components (partial stresses) respectively. The intensity S is highly significantly different than PSS (p<0,001) and STA (p<0,001) and depended on them. S is also found to be positively associated with PSS (p<0,001) and STA (p<0,001) in terms of total, positive and negative stresses. In addition, we found that PSS and STA have an interaction on each other. We conclude that the dimension PSS, introduced in our tri-transactional theory of stress, has to be taken into account in the assessment of the stress intensity generated by a stimulus or an activity (set of stimuli). The previous stress formula (S =PSS + ST) proposed in our previous study was revised according to new present study outcomes for the two activities. The corresponding model was found highly significant (p<0.001) and explained 83,8 % (mental arithmetic) and 73,10 % (relaxation) of the variance of the stress value S if the predicted variables are total stresses TPSS and TSTA (P<0.001) (TS= Constant + α TPSS + β TSTA). The negative stress (NS) for mental arithmetic (76,9 %) and the positive stress (PS) for relaxation (72,00 %) were well predicted by the independent variables TPSS and TSTA (NS = constant + αTPSS + βTSTA; PS = constant + αTPSS + βTSTA). The observed and predicted values using these equations were found to be strongly correlated with a Spearman coefficient (Rho) that ranges from 0.847 to 0.905 (p<0,001). As for the secondary objectives, the objective perceived stress (STA) values of activities were observed not to depend on age (p>0.05) and gender for the 2 activities, except for gender concerning the mental arithmetic (p<0.05). The variation of stress (TS – TPSS) depended on age (p<0.05) and gender for the 2 activities, except for gender concerning the relaxation activity (P>0.05). Emotional stress seemed to be significantly influenced by other partial stresses for relaxation activity. These empirical results prove the validity of our new model of stress applied to positive and negative activities. Keywords Mental arithmetic, Savasana-relaxation, Previous state of stress, Emotional stress, Mental stress, Physical stress, Stress formula * Corresponding author: f_ktiri@yahoo.com (Ktiri Fouad) Received: July 25, 2020; Accepted: August 28, 2020; Published: September 15, 2020 Published online at http://journal.sapub.org/ijap
... Yoga group was enrolled to a 4 weeks' yoga training program administered by a certified yoga instructor. Anulom Vilom Pranayam (alternate nostril breathing), [10] Bhramari Pranayam, [11] Shitali Pranayam, [12] Shitkari Pranayam, [12] Suryanamaskar, [13] and Shavasan [14] were included in the training in graded fashion [ Table 1]. ...
Article
Full-text available
Background: Yoga is reported to improve psychophysiological well-being through a careful combination of asanas (body posture exercises), pranayamas (voluntary breathing exercises), and dhyana (meditations). Aims and Objectives: The main objective of this study was to investigate the effects of yoga on respiratory efficiency parameters of young adults. Materials and Methods: Using simple random sampling, a total of 300 volunteers were divided into two groups: Yoga group (female = 72 and male = 78) and control group (female = 64 and male = 86). Yoga group was subjected to yoga training for 4 weeks. Forced expiratory volume in 1st s (FEV1), forced vital capacity (FVC), FEV1/FVC (%), peak expiratory flow rate, forced expiratory flow during middle 50% (FEF25–75%), FEF during 200–1200 ml of expiration (FEF200–1200 ml), and maximum voluntary ventilation were measured in both the groups using computerized spirometer, both before and after intervention. Results: All parameters were found to be increased following yoga. No significant change in these parameters was noted in the control group. Conclusion: Yoga improves respiratory efficiency in healthy individuals and can be included as an essential part of healthy lifestyle. It can be advocated as an adjunctive or alternative to conventional therapy for respiratory diseases. KEY WORDS: Yoga; Respiratory Function Tests; Vital Capacity; Peak Expiratory Flow Rate; Young Adult
... 8 The literature indicates that yoga-based lifestyle intervention favorably modifies various cardiovascular and metabolic parameters. [9][10][11] Various limbs of yoga, including asana, pranayama, and meditation, improve the sympathovagal response, which is evident from the increase in HRV and restoration of baroreflex sensitivity. 6,12 Accumulating evidence suggests that yoga might have a favorable effect on cardiac autonomic function. ...
Article
Full-text available
Autonomic dysfunction is an independent predictor of cardiovascular and all-cause mortality after myocardial infarction (MI). We tested the effects of a 12-week yoga-based cardiac rehabilitation program on heart rate variability (HRV) in 80 patients post-MI. This randomized controlled trial with two parallel groups was carried out in a tertiary care institution in India. The yoga group received 13 hospital-based structured yoga sessions as an adjunct to standard care. Control group participants received enhanced standard care involving three brief educational sessions with a leaflet on the importance of diet and physical activity. HRV was measured in all participants with lead II electrocardiogram (ECG) signals. One yoga group patient's data were excluded due to ECG abnormalities. Baseline measurement was done 3 weeks post-MI, and postintervention assessment took place at the 13th week. HRV frequency and time domain indices were analyzed. There were no significant between-group differences in the HRV time domain indices. Frequency domain indices showed significant between-group differences in HF power (absolute) (yoga vs. control: 114.42 [-794.80-7,993.78] vs. -38.14 [-4,843.50-1,617.87], p = 0.005) and total power (nu) (yoga vs. control: 44.96 [21.94] vs. -19.55 [15.42], p = 0.01) with higher HF power and total power (nu) in the yoga group. It should be noted that these results cannot be generalized to high risk patients. Respiratory frequency control to check for influence of respiratory rate on RR interval was not evaluated. This short-term yoga-based cardiac rehabilitation program had additive effects in shifting sympathovagal balance toward parasympathetic predominance while increasing overall HRV in optimally medicated post-MI patients.
... We have also previously reported that regular yoga practitioners display heightened metabolic flexibility (Tyagi et al. 2014) and there is evidence that regular yoga practitioners may experience a deeper resting state with higher RSA (Muralikrishnan et al. 2012) and lower metabolic rate (Chaya et al. 2006) at rest. Yoga has also been shown to enhance parasympathetic dominance (Bowman et al. 1997;Khattab et al. 2007) as well as enhance parasympathetic activity in normotensive and hypertensive patients (Santaella et al. 2014). The practice of yoga, has been likened to the 'flow state', which is described as a form of 'eustress' or desirable state of positive arousal caused by the perception of subjective control with maximum physiological efficiency and the down-regulation of functions irrelevant for task fulfilment (Csikszentmihalyi 2008;Peifer 2012;Selye 1983). ...
Article
Full-text available
Heart Rate Variability (HRV) and respiratory sinus arrhythmia are directly associated with autonomic flexibility, self-regulation and well-being, and inversely associated with physiological stress, psychological stress and pathology. Yoga enhances autonomic activity, mitigates stress and benefits stress-related clinical conditions, yet the relationship between autonomic activity and psychophysiological responses during yoga practices and stressful stimuli has not been widely explored. This experimental study explored the relationship between HRV, mood states and flow experiences in regular yoga practitioners (YP), non-yoga practitioners (NY) and people with metabolic syndrome (MetS), during Mental Arithmetic Stress Test (MAST) and various yoga practices. The study found that the MAST placed a cardio-autonomic burden in all participants with the YP group showing the greatest reactivity and the most rapid recovery, while the MetS group had significantly blunted recovery. The YP group also reported a heightened experience of flow and positive mood states compared to NY and MetS groups as well as having a higher vagal tone during all resting conditions. These results suggest yoga practitioners have a greater homeostatic capacity and autonomic, metabolic and physiological resilience. Further studies are now needed to determine if regular yoga practice may improve autonomic flexibility in non-yoga practitioners and metabolic syndrome patients. Clinical Trial No ‘ACTRN 2614001075673’
Chapter
The experience of stroke can significantly impact the physical health, psychosocial wellbeing of an individual. These consequences make the patients vulnerable to develop mental illnesses, ranging from dysthymia to as serious as severe depression with suicidal tendencies. There is a need for holistic therapies such as yoga-based lifestyle, which aim at improving quality of life on both physical and psychosocial domains. There is growing evidence indicating the potential use of yoga in improving an individual’s functional status post-stroke. This chapter aimed at reviewing the evidence for the effects of yoga in the prevention of stroke and its post-stroke rehabilitative potential. The literature suggests the need for integration of yoga therapy with the conventional treatment to curb the morbidity and mortality associated with stroke and its co-morbidities.
Article
Full-text available
Hypertension is a ubiquitous and serious disease. Regular exercise has been recommended as a strategy for the prevention and treatment of hypertension because of its effects in reducing clinical blood pressure; however, ambulatory blood pressure is a better predictor of target-organ damage than clinical blood pressure, and therefore studying the effects of exercise on ambulatory blood pressure is important as well. Moreover, different kinds of exercise might produce distinct effects that might differ between normotensive and hypertensive subjects. The aim of this study was to review the current literature on the acute and chronic effects of aerobic and resistance exercise on ambulatory blood pressure in normotensive and hypertensive subjects. It has been conclusively shown that a single episode of aerobic exercise reduces ambulatory blood pressure in hypertensive patients. Similarly, regular aerobic training also decreases ambulatory blood pressure in hypertensive individuals. In contrast, data on the effects of resistance exercise is both scarce and controversial. Nevertheless, studies suggest that resistance exercise might acutely decrease ambulatory blood pressure after exercise, and that this effect seems to be greater after low-intensity exercise and in patients receiving anti-hypertensive drugs. On the other hand, only two studies investigating resistance training in hypertensive patients have been conducted, and neither has demonstrated any hypotensive effect. Thus, based on current knowledge, aerobic training should be recommended to decrease ambulatory blood pressure in hypertensive individuals, while resistance exercise could be prescribed as a complementary strategy.
Article
Purpose: Assessment of short-term practice of relaxation therapy on autonomic and cardiovascular functions in first-year medical students. Design: Case-control, interventional study. Setting: Medical college laboratory. Subjects: Sixty-seven medical students, divided into two groups: study group (n = 35) and control group (n = 32). Intervention: Study group subjects practiced relaxation therapy (shavasana with a soothing background music) daily 1 hour for 6 weeks. Control group did not practice relaxation techniques. Measures: Cardiovascular parameters and spectral indices of heart rate variability (HRV) were recorded before and after the 6-week practice of relaxation therapy. Analysis: The data between the groups and the data before and after practice of relaxation techniques were analyzed by one-way analysis of variance and Student t-test. In the study group, prediction of low-frequency to high-frequency ratio (LF-HF) of HRV, the marker of sympathovagal balance, to blood pressure (BP) status was assessed by logistic regression. Results: In the study group, there was significant reduction in heart rate (p = .0001), systolic (p = .0010) and diastolic (p = .0021) pressure, and rate pressure product (p < .0001), and improvement in HRV indices, following 6 weeks of relaxation therapy. As determined by regression model, prediction of LF-HF to BP status was more significant (odds ratio, 2.7; p = .009) after practice of relaxation therapy. There was no significant alteration in these parameters in control subjects. Conclusion: Short-term practice of relaxation therapy can improve autonomic balance and promote cardiovascular health of medical students. Sympathovagal balance is directly linked to BP status in these individuals.
Article
Objective: High-normal blood pressure (BP) increases the risk of cardiovascular (CV) disease. The mechanisms underlying this increased risk are not clear. Sympathetic activation appears to be a potential mechanism linking high-normal BP to CV disease. This study examined whether high-normal BP compared with optimal BP is linked to sympathoexcitation at rest and/or during laboratory stressors. Methods: Heart rate (HR), BP and muscle sympathetic nerve activity (MSNA) were obtained at rest and during stress tests (sustained handgrip and mental stress) in 18 subjects (15 males and three females) with high-normal BP (systolic BP of 130-139 mmHg, diastolic BP of 85-89 mmHg, or both) and in 12 subjects (10 males and two females) with optimal BP (< 120/80 mmHg) matched for age (34 ± 3 years in both groups) and body mass index (25 ± 2 kg/m(2) in both groups). Results: Despite the higher resting BP levels, MSNA was higher in subjects with high-normal BP than in the optimal BP group (26 ± 3 vs 18 ± 2 bursts/min, p< 0.05). During sustained handgrip, MSNA increased by 37 ± 14% in high-normal BP group compared with an increase of 49 ± 15% in optimal BP group (p = 0.55). Changes during mental stress were 50 ± 28% and 37 ± 12%, respectively (p = 0.73). There were no significant differences in SBP responses to handgrip and mental stress between the high-normal and optimal BP groups. Baseline HR and chronotropic responses to stress tests were comparable between the two groups. Conclusion: In comparison with optimal BP, high-normal BP is associated with increased resting MSNA, but normal neural and circulatory responses to stress tests. These findings suggest that tonic activation of the sympathetic nervous system may precede overt arterial hypertension and contribute to an excess risk of CV disease in subjects with high-normal BP.
Article
Objective: The measurement of heart rate variability (HRV) is often applied as an index of autonomic nervous system (ANS) balance and, therefore, myocardial stability. Previous studies have suggested that relaxation or mind-body exercise can influence ANS balance positively as measured by HRV but may act via different mechanisms. No studies, to the authors' knowledge, have examined the acute response in HRV to interventions combining relaxation and mind-body exercise. The objective of this study was to compare the acute HRV responses to Yoga Nidra relaxation alone versus Yoga Nidra relaxation preceded by Hatha yoga. Design: This was a randomized counter-balanced trial. Setting: The trial was conducted in a university exercise physiology laboratory. Subjects: Subjects included 20 women and men (29.15±6.98 years of age, with a range of 18-47 years). Interventions: Participants completed a yoga plus relaxation (YR) session and a relaxation only (R) session. Results: The YR condition produced significant changes from baseline in heart rate (HR; beats per minute [bpm], p<0.001) and indices of HRV: R-R (ms, p<0.001), pNN50 (%, p=0.009), low frequency (LF; %, p=0.008) and high frequency (HF; %, p=0.035). The R condition produced significant changes from baseline in heart rate (bpm, p<0.001) as well as indices of HRV: R-R (ms, p<0.001), HF (ms(2), p=0.004), LF (%, p=0.005), HF (%, p=0.008) and LF:HF ratio (%, p=0.008). There were no significant differences between conditions at baseline nor for the changes from baseline for any of the variables. Conclusions: These changes demonstrate a favorable shift in autonomic balance to the parasympathetic branch of the ANS for both conditions, and that Yoga Nidra relaxation produces favorable changes in measures of HRV whether alone or preceded by a bout of Hatha yoga.
Article
A consistent link appears to exist between predominance of vagal or sympathetic activity and predominance of HF or LF oscillations, respectively: RR variability contains both of these rhythms, and their relative powers appear to subserve a reciprocal relation like that commonly found in sympathovagal balance. In this respect, it is our opinion that rhythms and neural components always interact, just like flexor and extensor tones or excitatory and inhibitory cardiovascular reflexes, and that it is misleading to separately consider vagal and sympathetic modulations of heart rate. In humans and experimental animals, functional states likely to be accompanied by an increased sympathetic activity are characterized by a shift of the LF-HF balance in favor of the LF component; the opposite occurs during presumed increases in vagal activity. In addition, LF oscillation evaluated from SAP variability appears to be a convenient marker of the sympathetic modulation of vasomotor activity. Although based on indirect markers, the exploration in the frequency domain of cardiovascular neural regulation might disclose a unitary vision hard to reach through the assemblage of more specific but fragmented pieces of information.
Article
In young men (mean age 25 years) with borderline hypertension the authors have documented a reduction in systolic blood pressure and muscle sympathetic nerve activity 60 mins after 45 mins of submaximal treadmill exercise. The aim of this study was to determine if post exercise hypotension occurs in normotensive young men, and if so, if it is accompanied by a decrease in sympathetic nerve activity. Replicating a previous protocol, the authors recorded blood pressure, heart rate, plasma noradrenaline and muscle sympathetic nerve activity (microneurography; peroneal nerve) before and 60 mins after submaximal treadmill exercise. Ten healthy male volunteers (mean age 28 +/- 5 years). Forty-five minutes of treadmill exercise at 70% of resting heart rate reserve. In contrast to borderline hypertensive subjects, prior exercise had no effect on either systolic or diastolic blood pressure or muscle sympathetic nerve activity in healthy volunteers. Plasma noradrenaline concentrations were similar before and after exercise. Resting heart rate (56 +/- 3 versus 70 +/- 3 beats/min; P less than 0.002), and sympathetic burst frequency (10 +/- 4 versus 20 +/- 2 bursts/min; P = 0.026) were lower in normal than in borderline hypertensive men. At rest, discharge to muscle sympathetic nerves is increased in young borderline hypertensive men; and blood pressure and sympathetic nerve activity are decreased after exercise in borderline hypertensive but not normotensive men. These observations suggest that the depressor response to prolonged rhythmic exercise in young men with borderline hypertension may be due in part to transient suppression of augmented central sympathetic outflow.