ArticlePDF Available

Acute Changes in Autonomic Nerve Activity during Passive Static Stretching

Authors:
Article

Acute Changes in Autonomic Nerve Activity during Passive Static Stretching

Abstract and Figures

This study aimed to investigate the acute change of static stretching (SS) on autonomic nerve activity and to clarify the effect of SS on systemic circulation. Twenty healthy young, male volunteers performed a 1-min SS motion of the right triceps surae muscle, repeated five times. The autonomic nerve activity balance was obtained using second derivatives of the photoplethysmogram readings before (pre), during, and after (post) SS. Heart rate and blood pressure (BP) were also measured. The autonomic nerve activity significantly changed to parasympathetic dominance by SS as compared with pre. In addition, for SS, the autonomic nerve activity slowly changed to sympathetic dominance after completion of all sets of stretching, but these value did not return to pre during the 5 minutes after the completion of all sets of stretching, with parasympathetic dominance continuing by 4 minutes after SS. The BP and HR transiently increased during SS and decreased after SS. In addition, HR significantly decreased after completion of all sets of SS.The possibility that the response during SS may differ from the response during active static stretching is shown.
Content may be subject to copyright.
American Journal of Sports Science and Medicine, 2014, Vol. 2, No. 4, 166-170
Available online at http://pubs.sciepub.com/ajssm/2/4/9
© Science and Education Publishing
DOI:10.12691/ajssm-2-4-9
Acute Changes in Autonomic Nerve Activity during
Passive Static Stretching
Takayuki Inami1,*, Takuya Shimizu2, Reizo Baba3, Akemi Nakagaki4
1School of Exercise and Health Sciences, Edith Cowan University, Joondalup Drive, Joondalup, WA, Australia
2Graduate School of Health and Sports Sciences, Chukyo University, Tokodachi, Toyota, Aichi, Japan
3Department of Pediatric Cardiology, Aichi Children’s Health and Medical Center, Osakada, Obu, Aichi, Japan
4Reproductive Health Nursing/Midwifery, Graduate School of Nursing, Nagoya City University, Japan
*Corresponding author: inami0919@gmail.com
Received June 06, 2014; Revised July 12, 2014; Accepted July 16, 2014
Abstract This study aimed to investigate the acute change of static stretching (SS) on autonomic nerve activity
and to clarify the effect of SS on systemic circulation. Twenty healthy young, male volunteers performed a 1-min SS
motion of the right triceps surae muscle, repeated five times. The autonomic nerve activity balance was obtained
using second derivatives of the photoplethysmogram readings before (pre), during, and after (post) SS. Heart rate
and blood pressure (BP) were also measured. The autonomic nerve activity significantly changed to parasympathetic
dominance by SS as compared with pre. In addition, for SS, the autonomic nerve activity slowly changed to
sympathetic dominance after completion of all sets of stretching, but these value did not return to pre during the 5
minutes after the completion of all sets of stretching, with parasympathetic dominance continuing by 4 minutes after
SS. The BP and HR transiently increased during SS and decreased after SS. In addition, HR significantly decreased
after completion of all sets of SS.The possibility that the response during SS may differ from the response during
active static stretching is shown.
Keywords: sympathetic nerve activity, parasympathetic nerve activity, triceps surae muscle, static stretching,
blood pressure, heart rate
Cite This Article: Takayuki Inami, Takuya Shimizu, Reizo Baba, and Akemi Nakagaki, Acute Changes in
Autonomic Nerve Activity during Passive Static Stretching.” American Journal of Sports Science and Medicine,
vol. 2, no. 4 (2014): 166-170. doi: 10.12691/ajssm-2-4-9.
1. Introduction
Static stretching (SS) is a form of physical exercise in
which a specific skeletal muscle (or muscle group) is
deliberately stretched and reflects the mechanical
characteristics of skeletal muscle. It is widely used to
increase articular range of motion (ROM) by favorably
affecting the flexibility of muscles and tendons [1,2]. In
addition, it is reported that SS can provide “relaxation”
like the techniques employed in the field of psychology
[3,4].These reports have indicated that extension stimuli
on the muscles may induce advantageous changes in the
balance of autonomic nerve activity; however, only a
small number of studies focusing on SS and autonomic
nerve activity have been conducted.
We could find three studies in which SS was evaluated
by analyzing the changes in autonomic nerve activity
based on the changes in heart rate variability (HRV) in
human subjects. Saito, et al. [5] conducted SS (trunk
flexion) on healthy volunteers and showed that
parasympathetic nerve activity was significantly higher
after SS than it was before SS.Farinatti, et al. [6] applied
SS (trunk flexion) to subjects with a low level of
flexibility and showed that parasympathetic nerve activity
decreased remarkably during SS and was significantly
higher after SS than it was before SS. Mueck-Weymann,
et al. [7] conducted SS on the large muscles of body-
building athletes for 28 days and confirmed a significant
increase in parasympathetic nerve activity and a
significant decrease in sympathetic nerve activity after the
completion. Based on these findings, it can be understood
that the balance of autonomic nerve activity shifts to the
sympathetic nerve activity-dominant state during SS and
the parasympathetic nerve activity-dominant state after SS.
All of these reports involve the response to active SS;
however, there is no report on autonomic nerve activity
relating to passive SS. According to Mohr, et al. [8],SS
has to be conducted first in order to achieve the maximum
effect of SS, and Alter [2] stated that the tension caused by
muscle contraction must be suppressed to the minimum in
order to minimize active resistance. These precedent
studies have a problem in that there is an extremely high
possibility that the muscles other than the target muscle
are under tension, because the trunk flexion was
conducted actively. Actually, the influence of SS on the
nervous system is known to be transmitted to the sites to
which SS is not conducted [9,10]. It is thus assumed that
active SS and passive SS have different influences on the
autonomic nerve activity, although the term “SS” is used
collectively.
American Journal of Sports Science and Medicine 167
We hypothesizes that the changes in autonomic nerve
activity upon passive SS are different from the response
following active SS. This study aims at investigating the
acute effect on autonomic nerve activity when SS is
conducted passively.
2. Materials and Methods
2.1. Participants
This study was approved by the local ethics committee
and conducted in accordance with the Declaration of
Helsinki. The purpose, procedures, and risks of the study
were informed, and a written informed consent was
obtained from each participant. Twenty non-smoking,
healthy male adults (aged 18 to 20 years, 19.3 years on
average) without cardiovascular, orthopedic, or
neurological diseases were recruited as study subjects. SS
was conducted for the right triceps surae muscle. They had
not been involved in any resistance training or stretching
program before the study. The sample size was calculated
on the basis of an α level of 0.05 and a power (1-β) of 0.8,
with an estimated 20% difference in ROM before and
after of SS using data from a previous study [11]. Their
height was 175.0±6.4cm(mean ± standard error: the same
below) and body weight was 68. 9±8.2kg.
2.2. Study Design
Figure 1. Protocol and measurement system
The study participants visited the laboratory on three
occasions at the same time of day, with at least 48 h
between visits; all experimental trials were completed
within 3weeks. A full familiarization with the SS protocol
and test procedures was provided during the first session,
whereas the subsequent two visits were used to complete
the following experimental protocol, in a randomized
order: 1) control session (no stretching); 2) five sets of 1-
min passive plantar flexor SS, as described previously
[11,12]. Data were collected during a period of 30-min
including these stretching sessions, a period of resting in
the sitting position (the knee fully extended) for 15-min
before stretching (referred to as “pre” below), and a 5-min
period after stretching (referred to as “post” below). The
temperature in the experimental room was set at 25°C.
The subjects were asked not to consume any alcohol on
the day before measurement and not eat breakfast on the
day of measurement. The experiment was conducted while
external environmental factors that could affect
measurement were minimized, and care was taken to
ensure subject silence and comfort. The protocol and
measurement system are shown in Figure 1.
2.3. Static Stretching Protocol
Two techniques, SS and a control with no stretching
were used, and SS was conducted passively to minimize
active resistance. In SS, the knee joint was in the extended
position and the ankle joint in the maximally dorsiflexed
position in a sitting position (the knee fully extended) [13].
For control the subjects rested in sitting position (the knee
fully extended). The load with which a subject himself felt
to have an “appropriate stretched feeling” or “slightly taut
feeling” [14] was measured in advance with a hand-held
dynamometer (Loadcell LU-100KSB34D of Kyowa
Electronic Instruments Co., Ltd.; Strain amplifier: F-420
of Uniplus Corporation), and the passive external force
during repeated stretching was controlled to impose the
same load in the respective sets of the respective
stretching. This position was then held at a constant angle
for 1 min, and this stretching procedure was repeated 5
times with a 1-min interval between sets (total 10-min). In
addition, the maximum ROM of the ankle joint was
measured with a goniometer of Tokyo University [13].
2.4. Measurement of Autonomic Nerve Activity,
Blood Pressure (BP) and Heart Rate (HR)
A large number of attempts of evaluating the balance of
autonomic nerve activity by analyzing the waveform of an
electrocardiogram and pulse wave have been reported as
evaluation of autonomic nerve activity. The method
involving frequency analysis of an electrocardiogram or
second derivative of photoplethysmogram (SDPTG)
quantifies sympathetic nerve activity and parasympathetic
nerve activity separately and is clinically applied. In
particular, SDPTG performs measurements using an
optical sensor noninvasively at the fingertips and reflects
changes in the absorbance of hemoglobin independently
from skin tension or properties of the subcutaneous fat,
and thus involves more noninvasive characteristics than
electrocardiography in which electrodes are attached. The
waveform of SDPTG is composed of five components, a
through e. It is reported that the a-a interval of SDPTG
and the R-R interval of electrocardiogram are highly
correlated with a correlation coefficient of 0.992 from
young to middle-aged to elderly individuals; this is
reportedly higher than the 0.977 correlation coefficient
between the R-R interval of electrocardiogram and finger
photoplethysmogram [15]. Further, it is shown in the
report that the spectrum power values obtained from the
SDPTG a-a interval correspond to the spectrum power
values obtained from electrocardiogram from the low-
frequency band to the high-frequency band [15].
Accordingly, analysis of autonomic nerve activity using
SDPTG has physiological significance equivalent to that
obtained using electrocardiogram.
A SDPTG (Artett C of U-Medica Inc., Osaka, Japan)
was used for the measurement of autonomic nerve activity.
The pulse waveforms (a to e waves: Figure 1) output on a
personal computer were used for frequency analysis for
168 American Journal of Sports Science and Medicine
the a-a interval using software for autonomic function
evaluation and analysis exclusively used for Artett. Based
on the results of the frequency analysis, the low-frequency
component (LF) was set at 0.04 to 0.15Hz and the high
frequency component (HF) at 0.15 to 0.4Hz [16]. The
power spectral densities at the respective frequency zones
were calculated, and the LF and HF (mainly
parasympathetic nerve activity) and their ratio LF/HF
(mainly sympathetic nerve activity), and HR were
obtained every 1-min. Since HF and LF/HF differ greatly
among individuals, normalization was performed so that
the means of HF and LF/HF were 0 and the standard
deviation was 1 during the continuous measurement
period for each subject, and the HF and LF/HF converted
into normal distribution are expressed as nHF and
n(LF/HF), respectively. Because the balance of the
autonomic nerve activity have a reciprocal relationship, in
the estimation of the balance of the autonomic nerve
activity, when
( )
nHF n LF/ HF 0−>
it was considered to be parasympathetic nerve activity-
dominant, and when
( )
nHF n LF/ HF 0
−<
it was considered to be sympathetic nerve activity-
dominant [17].
An average blood pressure (BP) also measured over a
1-min period, and included measuring the systolic (SBP)
and diastolic blood pressures (DBP) with an automatic
digital BP meter (HEM-7020, OMRON, Tokyo, Japan).
The subjects were requested to perform respiration at a
rate of 10 times (exhalation for 3 seconds and inhalation
for 3 seconds) per minute in rhythm with an electronic
metronome (Digital metronome: DM-70, Seiko Watch
Corporation, Tokyo, Japan)during the measurement so
that the value evaluated as HF from the relationship
between the frequency and respiration rate did not overlap
LF [18]. Respiration training was conducted for 10
minutes under monitoring before each measurement and
respiration was confirmed visually also during
measurement, since the measurement was conducted
under regulated respiration.
2.5. Statistical Analysis
The values for each parameter before SS (pre) were
averaged over the 5-min period immediately before SS.
One-way analysis of variance (ANOVA) using repeated
measurements and two-way ANOVA were conducted for
each numerical data set; Bonferroni’s tests were used for
post hoc analyses. SPSS, version 12.0 for Windows (SPSS,
Chicago, IL, USA) was used for statistical analyses, and
the statistically significant level was set at less than 5%.
Figure 2. Changes in each parameter
It is shown that changes in a) ROM, b) autonomic nerve activity, c) SBP, d) DBP, and e) HR. The yellow makers indicate the SS phase.
*: p< 0.05; **: p < 0.01, significantly different from baseline.
American Journal of Sports Science and Medicine 169
3. Results
The changes in each parameter are shown in Figure 2-a
to e. The ROM increased significantly until 5-min post SS
(Figure 2-a). The autonomic nerve activity significantly
changed to parasympathetic dominance by SS as
compared with pre. In addition, for SS, the autonomic
nerve activity slowly changed to sympathetic dominance
after completion of all sets of stretching, but these value
did not return to pre during the 5-min after the completion
of all sets of stretching, with parasympathetic dominance
continuing by 4-min after SS(Figure 2-b). The values
obtained for control showed no large change during
measurement(Figure 2-b). No extrasystole was observed
in any subjects by diagnosis with the analysis software for
exclusive use. The changes in SBP, DBP and HR are
shown in Figure 2-c, d and e. These parameters transiently
increased during SS and decreased after SS. In addition,
HR significantly decreased after completion of all sets of
SS (3-min).
4. Discussion
The major results of this study are as follows: 1) The
balance of autonomic nerve activity shifts to a
parasympathetic nerve-dominant state during passive SS;
and2) the parasympathetic nerve-dominant state continues
even after the completion of SS (for at least 5 minutes
after completion). The study on the autonomic nerve
activity upon passive SS in humans is valuable and the
results of this study can be said to be a new fact which can
be added to the findings concerning SS and relaxation.
Considering the precedent studies all together [5,6,7],
when SS is conducted actively, the autonomic nerve
activity shifts to a sympathetic nerve-dominant state
during SS and a parasympathetic nerve-dominant state
after the completion of SS. Also in this study, the balance
of autonomic nerve activity shifts to a parasympathetic
nerve-dominant state after SS, which supports the results
of the precedent studies. However, unlike active SS, the
response during SS shifted to a parasympathetic nerve-
dominant state. This result indicates the possibility that the
process differs between active SS and passive SS,
although the response after the completion of SS is similar
for both. Murata et al. [19] investigated autonomic nerve
activity following passive SS in decerebrate cats as a
precedent study of an animal experiment level. According
to Murata et al. [19], cardiac sympathetic nerve activity
increased only at the time of start of SS (where analysis
was carried out in the condition in which parts of the
cardiac vagal nerve and the stellate ganglion were cut),
and this response has been confirmed muscle sympathetic
nerve activity in human [20]. Since analysis was
conducted for one minute in this study, not only cardiac
sympathetic nerve activity that increases only at the start
of SS, but also stimulation of the suppression system that
subsequently occurs might be analyzed, and as a result,
the balance of autonomic nerve activity is considered to
shift to a parasympathetic nerve-dominant state. In
addition,transient increases in SBP,DBP and HR have
been reported in response to local SS of the triceps surae
muscle [20,21,22], and our results support these
previously described findings. Although the SS method
was different in the previous studies, the transient changes
in hemodynamic properties can be associated with
mechanical stress and modulations of the baroreflex
sensitivity and vagal tone during SS [20,21,22]. It is
difficult to identify the mechanism from the results of this
study; however, it is considered that the reduction in HR
due to SS is mainly due to suppression of sympathetic
nerve activity [2], and the reduction in HR plays a role in
continuation of a parasympathetic nerve-dominant state by
SS.
Limb position is considered to be one of the causes for
the difference in autonomic nerve activity between active
SS and passive SS. There are a large number of muscle
spindles and proprioceptors in the diaphragm and the
intercostals, which involve in up-and-down movements of
the ribs [23]. In the trunk flexion which was conducted in
the precedent studies, SS was conducted with the hip joint
bent maximally so that a large pressure was applied to the
thoracoabdominal part and muscle extension stimuli
would occur at the muscles other than the hamstring
muscle (for example, external oblique muscle and internal
oblique muscle). As mentioned above, the influence of SS
on the nervous system is known to be transmitted to the
sites to which SS is not conducted [9,10]. Further, it is
assumed that respiratory load (load compensation reflex)
due to the position at which the trunk was anteverted
might prevent respiration by an ordinary respiration
method (with relaxation) to affect the balance of
autonomic nerve activity.
There are two main limitations associated with the
present study. The first limitaionsis that HRV analysis
using SDPTG conducted. We used SDPTG to minimize
invasion that included attachment of electrodes as much as
possible. The usability of investigation of autonomic
nerve activity using SDPTG has already been evidenced
by Yamaguchi, et al.; however, influence of changes in
body motion during SS, that is, due to dorsiflexion of the
ankle joint, on measurements is unclear. This point should
be sufficiently considered in further studies.The second
limitation is that all the parameters were calculated as an
average over 1-min intervals. According to Cui et al. [20],
the HR increased between one and three beats during SS.
This suggests that a hyper-acute effect of SS may occur,
and future studies should employ a better temporal
analysis, with times up to 1 min. However, because Cui et
al. [20] employed a different SS paradigm (5-s × 25 sets),
there is also a possibility that the SS performance time had
an effect. The precise effect of SS time should be
investigated in future studies.
In summary, autonomic nerve activity shifts to a
parasympathetic nerve-dominant state by passive static
stretching, and the effect continues for at least five
minutes after the completion. The possibility that the
response during SS may differ from the response during
active static stretching is shown.
References
[1] American College of Sports Medicine Position Stand., “The
recommended quantity and quality of exercise for developing and
maintaining cardiorespiratory and muscular fitness, and flexibility
in healthy adults,” Med Sci Sports Exerc, 30. 975-991. 1998.
170 American Journal of Sports Science and Medicine
[2] Alter, M.J., “Science of flexibility,” 3rd edition, Human Kinetics
Pub, Champaign, Illinois, 2004.
[3] Khattab, K., Khattab, A.A., Ortak, J., Richardt, G., Bonnemeier,
H., Iyengar yoga increases cardiac parasympathetic nervous
modulation among healty yoga practitioners,” Evid Based
Complement Alternat Med, 4. 511-517. 2007.
[4] Lu, W.A., Kuo, C.D., “The effect of Tai Chi Chuan on the
autonomic nervous modulation in older persons,” Med Sci Sport
Exerc, 35. 1972-1976. 2003.
[5] Saito, T., Hono, T., Miyachi, M., Effects of stretching on
cerebrocortical and autonomic nervous system activities and
systemic circulation,” J Phys Med, 12. 2-9. 2001.
[6] Farinatti, P.T., Brandao, C., Soares, P.P., Duarte, A.F., “Acute
effects of stretching exercise on the heart rate variability in
subjects with low flexibility levels,” J Strength Cond Res, 25.
1579-1585. 2011.
[7] Mueck-Weymann, M., Janshoff, G., Mueck, H., Stretching
increases heart rate variability in healthy athletes complaining
about limited muscular flexibility,” ClinAuton Res, 14. 15-18.
2004.
[8] Mohr, K.J., Pink, M.M., Elsner, C., Kvitne, R.S.,
Electromyographic investigation of stretching: The effect of
warm-up,” Clin J Sport Med, 8. 215-220. 1998.
[9] Avela. J., Kyrolainen, H., Komi, P.V.,“Altered reflex sensitivity
after repeated and prolonged passive muscle stretching,”J
ApplPhysiol, 86. 1283-1291. 1999.
[10] Cramer, J.T., Housh, T.J., Weir, J.P., Johnson, G.O., Coburn, J.W.,
Beck, T.W., “The acute effects of static stretching on peak torque,
mean power output, electromyography, and mechanomyography,”
Eur J ApplPhysiol, 93. 530-539. 2005.
[11] Mizuno, T., Matsumoto, M., Umemura, Y., “Viscoelasticity of the
muscle-tendon unit is returned more rapidly than range of motion
after stretching,” Scnad J Med Sci Sports, 23. 23-30. 2013.
[12] Morse, C.I., Degans, H., Seynnes, O.R., Maganaris, C.N., Jones,
D.A., “The acute effect of stretching on the passive stiffness of the
human gastrocnemius muscle tendon unit,” J Phyiol, 586. 97-106.
2008.
[13] Inami, T., Shimizu, T., Miyagawa, H., Inoue, M., Nakagawa, T.,
Takayanagi, F. Niwa, S.,“Effect of two passive stretching methods
for triceps surae on dorsiflexion of ankle joint,” J Phys Fitness
Sports Med, 59. 549-554. 2010.
[14] Kawakami, Y., Oda, T., Kurihara, T., Chino, K., Nagayoshi, T.,
Kanehara, H., Fukunaga, T., Kuno, S., “Musculoskeletal factors
influencing ankle joint range of motion in the middle-aged and
elderly individuals,” Jpn J Phys Fitness Sports Med, 52. 149-156.
2003.
[15] Yamaguchi, K., Sasabe, T., Tajima, S., Watanebe, Y., “The
evaluation of fatigue by acceleration plethysmogram,” J ClinExp
Med, 22. 646-653. 1009.
[16] 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. 93. 1043-1065. 1996.
[17] Yoshida, Y., Yokoyama, K., Takada, H., Iwase, S.,“Heart rate
variability before fainting under the graded local of artificial
gravity,” AutonNervSyst,43. 453-459. 2006.
[18] Matsumoto, T., Matsunaga, A., Hara, M., Saito, M., Yonezawa, R.,
Ishii, A., Kutsuna, T., Yamamoto, K., Masuda, T., “Effect of the
breathing mode characterized by prolonged expiration on
respiratory and cardiovascular responses and autonomic nervous
activity during the exercise,” Jpn J Phys Fit Sport Med, 57. 315-
326. 2008.
[19] Murata, J., Matsukawa, K., Cardiac vagal and sympathetic
efferent discharge are differentially modified by stretch of skeletal
muscle,” Am J Phyiol Heart Circ, 280. H237-H245. 2001.
[20] Cui, J., Blaha, C., Moradkhan, R., Gray, K.S., Sinoway, L. I.,
Muscle sympathetic nerve activity responses to dynamic passive
muscle stretch in humans,” J Physiol, 576. 625-634. 2006.
[21] Drew, R.C., Bell, M.P.D., White, M.J., “Modulation of
spontaneous baroreflex control of heart rate and indexes of vagal
tone by passive calf muscle stretch during graded metaboreflex
activation in humans,” J ApplPhysiol, 104. 716-723. 2008.
[22] Fisher, J.P., Bell, M.P.D., White, M.J., “Cardiovascular responses
to human calf muscle stretch during varying levels of muscle
metaboreflex activation,” ExpPhysiol, 90. 773-781. 2005.
[23] Euler, C.V.,On the role of proprioceptors in perception and
execution of motor acts with special reference to breathing,” In:
PengellyLD, Rebuch AS, Campbell EJM eds, Loaded breathing,
Longman Canada, 139-154. 1973.
... In addition, it has also been reported that static stretching can support muscle relaxation (Khattab et al., 2007). These reports indicate those stretch stimuli in the muscles can support positive changes in the autonomic nervous system (ANS) (Inami et al., 2014). ...
... Consequently, any strategy that favors reducing SV-b and increasing HRV can be considered beneficial for the CVS. However, many studies are reporting that the balance of the ANS is dominated by sympathetic nerve activity during SS and parasympathetic nerve activity becomes dominant after SS (Farinatti et al., 2011;Inami et al., 2014). ...
Article
Full-text available
This study aimed to examine the acute effect of different durations of static stretching on heart rate variability (HRV) and, the anaerobic capacity of moderately physically active men during the Wingate anaerobic test (WAnT) at two different pre-exercise periods. Sixty-five healthy young male volunteers performed 10 s static stretching (STS) and 30 s static stretching (LTS) consisting of five static stretching exercises before WAnT on two non-consecutive days. HRV was measured pre (60 s), during (30 s) and post (60 s) WAnT after two different periods of static stretching. Anaerobic capacity variables were also measured during WAnT. STS and LTS had similar effects on other HRV parameters except for Mean-RR during the WAnT. There was no significant difference between the protocols applied in any of the anaerobic capacity test values. But there was a negatively significant relationship between the average power output of 30 s static stretching and pNN50. This result has shown that STS and LTS exercises have a similar effect during maximal exercise, so if the practitioners carry out static stretching exercises before maximal or high-intensity exercise, it is recommended to perform the STS exercise in terms of the economy of the exercise.
... In contrast, passive stretching in rodent studies included: static mechanical forces employed either without the use of anesthetics (e.g., via an implanted stretching apparatus) or stretching while animals were anesthetized employing dynamic mechanical forces, for example during stretch-shortening contractions/cycles (i.e., SSC protocols including both concentric and eccentric stretching muscle contractions) [25,40,41] Stretching terminology used in human studies is primarily derived from the field of sports medicine and differs in meaningful ways [58]. For example, using sports medicine terminology, yogic stretching includes passive or static-passive stretching where the posture is held-for elongation-with support from some other part of the body or with the assistance of a partner or some other apparatus (i.e., props) between 10 seconds and less than one minute [59]. However, this passive stretching differs from rodent studies because humans purposely cooperate and are receptive (i.e., they try to relax the targeted area). ...
Article
Full-text available
Objective To conduct a systematic review evaluating the impact of stretching on inflammation and its resolution using in vivo rodent models. Findings are evaluated for their potential to inform the design of clinical yoga studies to assess the impact of yogic stretching on inflammation and health. Methods Studies were identified using four databases. Eligible publications included English original peer-reviewed articles between 1900–May 2020. Studies included those investigating the effect of different stretching techniques administered to a whole rodent model and evaluating at least one inflammatory outcome. Studies stretching the musculoskeletal and integumentary systems were considered. Two reviewers removed duplicates, screened abstracts, conducted full-text reviews, and assessed methodological quality. Results Of 766 studies identified, 25 were included for synthesis. Seven (28%) studies had a high risk of bias in 3 out of 10 criteria. Experimental stretching protocols resulted in a continuum of inflammatory responses with therapeutic and injurious effects, which varied with a combination of three stretching parameters––duration, frequency, and intensity. Relative to injurious stretching, therapeutic stretching featured longer-term stretching protocols. Evidence of pro- and mixed-inflammatory effects of stretching was found in 16 muscle studies. Evidence of pro-, anti-, and mixed-inflammatory effects was found in nine longer-term stretching studies of the integumentary system. Conclusion Despite the overall high quality of these summarized studies, evaluation of stretching protocols paralleling yogic stretching is limited. Both injurious and therapeutic stretching induce aspects of inflammatory responses that varied among the different stretching protocols. Inflammatory markers, such as cytokines, are potential outcomes to consider in clinical yoga studies. Future translational research evaluating therapeutic benefits should consider in vitro studies, active vs. passive stretching, shorter-term vs. longer-term interventions, systemic vs. local effects of stretching, animal models resembling human anatomy, control and estimation of non-specific stresses, development of in vivo self-stretching paradigms targeting myofascial tissues, and in vivo models accounting for gross musculoskeletal posture.
... And how does stretching intensity affect the outcomes? Performing unilateral PS induces improvements in passive ROM in non-local and non-stretched joints (Behm et al., 2021a), and consecutive sets of SS provoke increases of parasympathetic activity that remain for 5 min post-SS (Farinatti et al., 2011;Inami et al., 2014). Further research is warranted. ...
... Acute changes in the tension-length relationship in muscle tissue lead to greater flexibility, affected by the individual stretch tolerance [41][42][43][44][45] and possibly changes in the muscle's viscoelasticity [46]. Acute increases in HRV have also been seen with stretching exercises [47][48][49][50][51]. ...
Article
Full-text available
Background Persistent or recurrent neck pain is, together with other chronic conditions, suggested to be associated with disturbances of the Autonomic Nervous System. Acute effects on the Autonomic Nervous System, commonly measured using Heart Rate Variability, have been observed with manual therapy. This study aimed to investigate the effect on Heart Rate Variability in (1) a combination of home stretching exercises and spinal manipulative therapy versus (2) home stretching exercises alone over 2 weeks in participants with persistent or recurrent neck pain. Methods A randomized controlled clinical trial was carried out in five multidisciplinary primary care clinics in Stockholm from January 2019 to April 2020. The study sample consisted of 131 participants with a history of persistent or recurrent neck. All participants performed home stretching exercises daily for 2 weeks and were scheduled for four treatments during this period, with the intervention group receiving spinal manipulative therapy in addition to the home exercises. Heart Rate Variability at rest was measured at baseline, after 1 week, and after 2 weeks, with RMSSD (Root mean square of successive RR interval differences) as the primary outcome. Both groups were blinded to the other group intervention. Thus, they were aware of the purpose of the trial but not the details of the “other” intervention. The researchers collecting data were blinded to treatment allocation, as was the statistician performing data analyses. The clinicians provided treatment for participants in both groups and could not be blinded. A linear mixed-effects model with continuous variables and person-specific random intercept was used to investigate the group-time interaction using an intention to treat analysis. Results Sixty-six participants were randomized to the intervention group and sixty-five to the control group. For RMSSD, a B coefficient of 0.4 ( p value: 0.9) was found, indicating a non-significant difference in the regression slope for each time point with the control group as reference. No statistically significant differences were found between groups for any of the Heart Rate Variability indices. Conclusion Adding four treatments of spinal manipulation therapy to a 2-week program of daily stretching exercises gave no significant change in Heart Rate Variability. Trial Registration : The trial was registered 03/07/2018 at ClinicalTrials.gov, registration number: NCT03576846. ( https://pubmed.ncbi.nlm.nih.gov/31606042/ )
... Additionally, substantial static stretch-related cardiovascular and stress-related health benefits have been reported (18), with moderate magnitude improvements in cardiovascular parameters such as reduced arterial stiffness (19,20) and endothelium-dependent vasodilation and angiogenesis (21) after both acute and chronic stretching. The consistent application of SS can induce greater parasympathetic influence (22) and reduce chronic stress, stress perception, and cortisol release (23). Thus, the health benefits associated with stretching training, in addition to increases in ROM and decreased resistance, are both strong and convincing. ...
Article
Evidence for the effectiveness of acute and chronic stretching for improving range of motion is extensive. Improved flexibility can positively impact performances in activities of daily living and both physical and mental health. However, less is known about the effects of stretching on other aspects of health such as injury incidence and balance. The objective of this review is to examine the existing literature in these areas. The review highlights that both pre-exercise and chronic stretching can reduce musculotendinous injury incidence, particularly in running-based sports, which may be related to the increased force available at longer muscle lengths (altered force-length relationship) or reduced active musculotendinous stiffness, among other factors. Evidence regarding the acute effects of stretching on balance is equivocal. Longer-term stretch training can improve balance, which may contribute to a decreased incidence of falls and associated injuries and may thus be recommended as an important exercise modality in those with balance deficits. Hence, both acute and chronic stretching seem to have positive effects on injury incidence and balance, but optimum training plans are yet to be defined.
... And how does stretching intensity affect the outcomes? Performing unilateral PS induces improvements in passive ROM in non-local and non-stretched joints (Behm et al., 2021a), and consecutive sets of SS provoke increases of parasympathetic activity that remain for 5 min post-SS (Farinatti et al., 2011;Inami et al., 2014). Further research is warranted. ...
Article
Full-text available
Flexibility is the ability to move through full joint range of motion (ROM), while stretching is an intervention to improve flexibility and achieve other goals (e.g., post-exercise relaxation) (ACSM, 2021). Stretching has been promoted as mandatory in exercise programs (Behm, 2019; American Heart Association, 2020; ACSM, 2021), although this is changing toward an optional feature (Bull et al., 2020). There are different types of stretching, including active static stretching (SS—active lengthening of a muscle until the feeling of stretch or to the point of discomfort), passive static stretching (PS—where an external force is applied, e.g., by a coach or a colleague), dynamic stretching (DS –controlled movements through the joint ROM) and proprioceptive neuromuscular facilitation (PNF—combining PS with isometric contractions) (Behm, 2019). We will focus on SS and PS, since these methods are at the heart of most debates, with the pendulum swinging across the years (Behm et al., 2021b). The answer to “Can I perform a given exercise intervention?” is straightforward: when the benefits of an intervention outweigh its adverse effects or contra-indications, the answer is “yes.” Let us take the example of a study with 15 University students (Bengtsson et al., 2018), to illustrate the difference between the two questions: the negative acute effects of SS during a warm-up were restored if followed by isokinetic contractions, suggesting that SS can be included in a comprehensive warm-up protocol. University students are not representative of athletes, and a small sample does not warrant generalizations, but our point is that answering the first question (“Can I?”) does not answer the second question (“Do I have to?”). Focusing the research question and applicability on “Can I?” may be short-sighted. To date, we feel that research has focused more strongly on answering what stretching can do, while more information is required as to how stretching compares to alternative interventions. We will explore the differences between “Can I?” and “Do I have to?” stretch and their implications to warm-up, cool-down, ROM, and injury risk.
... And how does stretching intensity affect the outcomes? Performing unilateral PS induces improvements in passive ROM in non-local and non-stretched joints (Behm et al., 2021a), and consecutive sets of SS provoke increases of parasympathetic activity that remain for 5 min post-SS (Farinatti et al., 2011;Inami et al., 2014). Further research is warranted. ...
Preprint
The effects and usefulness of active and passive static stretching have raised heated debates. Over the years, the pendulum has swung from a glorified vision to their vilification. As most of the times, the truth often lies somewhere in-between. But even if there was no controversy surrounding the effects of static and passive stretching (which there is), and even if their effects were homogeneously positive (which they are not), that would not be sufficient to make stretching mandatory for practicing physical exercise, for most populations. Amidst the many discussions, an important issue has remained underexplored: the prerequisites to answer the question “Can I?” are not sufficient to answer the question “Do I have to?”, especially when alternative interventions are available. In this current opinion paper, we address four potential applications of stretching: (i) warm-up; (ii) cool-down; (iii) range of motion; and (iv) injury risk. We argue that while stretching can be used in the warm-up and cool-down phases of the training, its inclusion is not mandatory, and its effectiveness is still questionable. Stretching can be used to improve range of motion, but alternative and effective interventions are available. The role of stretching in injury risk is also controversial, and the literature often misinterprets association with causation and assumes that stretching is the only intervention to improve flexibility and range of motion. Overall, the answer to the question “Can I stretch?” is “yes”. But the answer to the question “Do I have to?” is “no, not really”.
Article
While muscle stretching has been commonly used to alleviate pain, reports of its effectiveness are conflicting. The objective of this review is to investigate the acute and chronic effects of stretching on pain, including delayed onset muscle soreness. The few studies implementing acute stretching protocols have reported small to large magnitude decreases in quadriceps and anterior knee pain as well as reductions in headache pain. Chronic stretching programs have demonstrated more consistent reductions in pain from a wide variety of joints and muscles, which has been ascribed to an increased sensory (pain) tolerance. Other mechanisms underlying acute and chronic pain reduction have been proposed to be related to gate control theory, diffuse noxious inhibitory control, myofascial meridians, and reflex-induced increases in parasympathetic nervous activity. By contrast, the acute effects of stretching on delayed onset muscle soreness are conflicting. Reports of stretch-induced reductions in delayed onset muscle soreness may be attributed to increased pain tolerance or alterations in the muscle's parallel elastic component or extracellular matrix properties providing protection against tissue damage. Further research evaluating the effect of various stretching protocols on different pain modalities is needed to clarify conflicts within the literature.
Article
Full-text available
ACSM Position Stand on The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Adults. Med. Sci. Sports Exerc., Vol. 30, No. 6, pp. 975-991, 1998. The combination of frequency, intensity, and duration of chronic exercise has been found to be effective for producing a training effect. The interaction of these factors provide the overload stimulus. In general, the lower the stimulus the lower the training effect, and the greater the stimulus the greater the effect. As a result of specificity of training and the need for maintaining muscular strength and endurance, and flexibility of the major muscle groups, a well-rounded training program including aerobic and resistance training, and flexibility exercises is recommended. Although age in itself is not a limiting factor to exercise training, a more gradual approach in applying the prescription at older ages seems prudent. It has also been shown that aerobic endurance training of fewer than 2 d·wk-1, at less than 40-50% of V˙O2R, and for less than 10 min-1 is generally not a sufficient stimulus for developing and maintaining fitness in healthy adults. Even so, many health benefits from physical activity can be achieved at lower intensities of exercise if frequency and duration of training are increased appropriately. In this regard, physical activity can be accumulated through the day in shorter bouts of 10-min durations. In the interpretation of this position stand, it must be recognized that the recommendations should be used in the context of participant's needs, goals, and initial abilities. In this regard, a sliding scale as to the amount of time allotted and intensity of effort should be carefully gauged for the cardiorespiratory, muscular strength and endurance, and flexibility components of the program. An appropriate warm-up and cool-down period, which would include flexibility exercises, is also recommended. The important factor is to design a program for the individual to provide the proper amount of physical activity to attain maximal benefit at the lowest risk. Emphasis should be placed on factors that result in permanent lifestyle change and encourage a lifetime of physical activity.
Article
The factors influencing ankle range of motion were investigated for 185 middle-aged and elderly subjects (116 women and 69 men, aged 48-86 years) . Each subject was seated with the right knee extended, and the ankle joint was passively dorsiflexed by a dynamometer with torque just tolerable for each subject, to measure the maximal dorsiflexion angle. During passive loading, elongation of muscle fibers in the gastrocnemius and Achilles tendon was determined in vivo by ultrasonography. There was a difference between women and men for the passive dorsiflexion angle (men smaller than women), which negatively correlated with muscle thickness of the posterior portion of the leg determined by ultrasonography. Both in women and men, the passive dorsiflexion angle negatively correlated with age, even after normalizing for maximal voluntary plantar flexion torque. Both elongation of muscle fibers and tendon was related to the passive dorsiflexion angle, and the ratio of tendon elongation to muscle fiber elongation positively correlated with the passive dorsiflexion angle. The active dorsiflexion angle, measured separately with the subject maximally dorsiflexing the ankle with no load, correlated with the passive dorsiflexion angle but not with age, and there was no gender difference. From the results it was suggested 1) that the mobility of the ankle joint is affected by elongation of both muscle fibers and tendon, but with the effect of the tendon being greater than that of muscle fibers, and 2) that muscle mass negatively affects passively-induced joint range of motion. Actively performed joint range of motion would be affected by elongation of the muscle-tendon corn plex and force-generating capability of the ankle. Gender difference in joint range of motion and the aging effect are related to these factors.
Article
Stretching for the triceps surae muscle in the knee flexed position (medical stretching: MS) and knee extended position (static stretching: SS) were performed and the effect on the dorsiflexion angle of the ankle joint was examined. Five elderly females were selected as subjects. We measured the maximal dorsiflexion angle of the ankle joint in the following leg positions: (1) the maximal dorsiflexion angle in the extended knee position (EDF angle) and (2) the maximal dorsiflexion angle in the 90° flexed-knee position (FDF angle). There was a significant increase in the maximal dorsiflexion angle after MS and SS were carried out (p<0.01), but there was no significant difference between MS and SS. It was concluded that MS for triceps surae is equally effective as SS in increasing the maximal dorsiflexion angle of the ankle joint.
Article
PURPOSE : The purpose of this study was to clarify the effects of prolonged expiration (PE) on respiratory and cardiovascular responses and autonomic nervous activity during the exercise. METHODS : Twenty-five healthy men (22 ± 1 years) were classified according to the breathing mode during the exercise : 2-second inspiration and 4-second expiration in 1 : 2 group, 3-second inspiration and 3-second expiration in 1 : 1 group and normal breathing in control group. The 6-minute exercise was performed at anaerobic threshold (AT) and 60%AT using a cycle ergometer as an exercise protocol. Respiratory rate (RR) and tidal volume (TV) were measured by the expired gas analysis. The power of low- (LF) and high-frequency components (HF) was analyzed from a Holter electrocardiogram to assess the heart rate variability. RESULTS : RR and LF/HF were significantly lower, TV and HF were significantly higher during the exercise of 60%AT and AT in the 1 : 1 and 1 : 2 groups than in the control group (P<0.05 or P<0.01). The increase of HR was significantly lower and that of HF was significantly higher during the exercise at 60%AT in the 1 : 2 group than in the 1 : 1 group (P<0.05). CONCLUSION : PE activated the parasympathetic nervous activity and consequently restrained an excessive increase of HR during the exercise at 60%AT.
Article
The purpose of this study was to clarify the time course of the viscoelasticity of gastrocnemius medialis muscle and tendon after stretching. In 11 male participants, displacement of the myotendinous junction on the gastrocnemius medialis muscle was measured ultrasonographically during the passive dorsiflexion test, in which the ankle was passively dorsiflexed at a speed of 1°/s to the end of the range of motion (ROM). Passive torque, representing resistance to stretch, was also measured using an isokinetic dynamometer. On five different days, passive dorsiflexion tests were performed before and 0, 15, 30, 60 or 90 min after stretching, which consisted of dorsiflexion to end ROM and holding that position for 1 min, five times. As a result, end ROM was significantly increased at 0, 15 and 30 min (P<0.05 each) after stretching as compared with each previous value. Passive torque at end ROM was also significantly increased after stretching. Although the stiffness of the muscle-tendon unit was significantly decreased immediately after stretching (P<0.05), this shift recovered within 15 min. These results showed that the retention time of the effect of stretching on viscoelasticity of the muscle-tendon unit was shorter than the retention time of the effect of stretching on end ROM.
Article
The study investigated the heart rate (HR) and heart rate variability (HRV) before, during, and after stretching exercises performed by subjects with low flexibility levels. Ten men (age: 23 ± 2 years; weight: 82 ± 13 kg; height: 177 ± 5 cm; sit-and-reach: 23 ± 4 cm) had the HR and HRV assessed during 30 minutes at rest, during 3 stretching exercises for the trunk and hamstrings (3 sets of 30 seconds at maximum range of motion), and after 30 minutes postexercise. The HRV was analyzed in the time ('SD of normal NN intervals' [SDNN], 'root mean of the squared sum of successive differences' [RMSSD], 'number of pairs of adjacent RR intervals differing by >50 milliseconds divided by the total of all RR intervals' [PNN50]) and frequency domains ('low-frequency component' [LF], 'high-frequency component' [HF], LF/HF ratio). The HR and SDNN increased during exercise (p < 0.03) and decreased in the postexercise period (p = 0.02). The RMSSD decreased during stretching (p = 0.03) and increased along recovery (p = 0.03). At the end of recovery, HR was lower (p = 0.01), SDNN was higher (p = 0.02), and PNN50 was similar (p = 0.42) to pre-exercise values. The LF increased (p = 0.02) and HF decreased (p = 0.01) while stretching, but after recovery, their values were similar to pre-exercise (p = 0.09 and p = 0.3, respectively). The LF/HF ratio increased during exercise (p = 0.02) and declined during recovery (p = 0.02), albeit remaining higher than at rest (p = 0.03). In conclusion, the parasympathetic activity rapidly increased after stretching, whereas the sympathetic activity increased during exercise and had a slower postexercise reduction. Stretching sessions including multiple exercises and sets acutely changed the sympathovagal balance in subjects with low flexibility, especially enhancing the postexercise vagal modulation.
Article
To compare the fine wire electromyographic (EMG) firing patterns during static stretches in the biceps femoris, soleus, and gastrocnemius before and after warm-up as well as over time. Experimental single group pretest-posttest design. Biomechanics research laboratory. Sixteen healthy volunteers 23 to 36 years of age with no history of lower extremity injury. Subjects performed one hamstring stretch and four calf stretches for 90 seconds, bicycled for 30 minutes as a warm-up, and stretched again. EMG was recorded at time 0, 30, 60, and 90 seconds during the stretches before and after warm-up. Recorded values were normalized to EMG during maximum manual muscle testing (MMT). A two-way analysis of variance with repeated measures (p < 0.05) was done to compare EMG activity during stretching before and after warm-up as well as over time. Low EMG activity was seen for all muscles (< 20% MMT). It was constant over the time of the stretch for all muscles, but it increased in the soleus during the bent knee stretch position. There was a statistically significant decrease in the EMG activity after the warm-up for the gastrocnemius using the traditional and heel off stretching positions and for the soleus using the heel off stretching position (p < 0.05). The biceps femoris EMG activity showed no significant differences before and after warm-up. EMG activity during static stretching was low. Overall, the EMG activity remained constant with time for a given stretch position. EMG of the soleus and gastrocnemius was significantly less after warm-up for some stretches, whereas the EMG activity of biceps femoris showed no differences before and after warm-up.