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Stochastic resonance whole body vibration increases perceived muscle relaxation but not cardiovascular activation: A randomized controlled trial

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AIM To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV), including muscle relaxation and cardiovascular activation. METHODS Sixty-four healthy students participated. The participants were randomly assigned to sham SR-WBV training at a low intensity (1.5 Hz) or a verum SR-WBV training at a higher intensity (5 Hz). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and self-reported muscle relaxation were assessed before and immediately after SR-WBV. RESULTS Two factorial analyses of variance (ANOVA) showed a significant interaction between pre- vs post-SR-WBV measurements and SR-WBV conditions for muscle relaxation in the neck and back [F(1,55) = 3.35, P = 0.048, η² = 0.07]. Muscle relaxation in the neck and back increased in verum SR-WBV, but not in sham SR-WBV. No significant changes between pre- and post-training levels of SBD, DBD and HR were observed either in sham or verum SR-WBV conditions. With verum SR-WBV, improved muscle relaxation was the most significant in participants who reported the experience of back, neck or shoulder pain more than once a month (P < 0.05). CONCLUSION A single session of SR-WBV increased muscle relaxation in young healthy individuals, while cardiovascular load was low. An increase in musculoskeletal relaxation in the neck and back is a potential mediator of pain reduction in preventive worksite SR-WBV trials.
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Achim Elfering, Christian Burger, Volker Schade, Lorenz Radlinger
ORIGINAL ARTICLE
758 November 18, 2016
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Stochastic resonance whole body vibration increases
perceived muscle relaxation but not cardiovascular
activation: A randomized controlled trial
Achim Elfering, Christian Burger, Department of Work and
Organizational Psychology, University of Bern, 3000 Bern,
Switzerland
Volker Schade, Centre for Human Resource Management and
Organizational Engineering, 3013 Bern, Switzerland
Lorenz Radlinger, Bern University of Applied Sciences, Health,
3008 Bern, Switzerland
Author contributions: Burger C performed the majority of
experiment; Schade V and Radlinger L co-ordinated and provided
the collection of data and were also involved in editing the
manuscript; Elfering A designed the study, did the analyses and
wrote the manuscript.
Supported by the Swiss National Accident Insurance Fund (SUVA,
Project “Stochastisches Resonanztraining”) to Achim Elfering,
Volker Schade and Lorenz Radlinger.
Institutional review board statement: This study was reviewed
and approved by the ethical committee of the responsible University
faculty.
Clinical trial registration statement: This study includes no
patients and is not registered.
Informed consent statement: All study participants, or their
legal guardian, provided informed verbal consent prior to study
enrollment.
Conflict-of-interest statement: All author(s) state that for
the current paper there is no nancial or other relationship that
might lead to a conict of interest. There is no nancial or other
involvement of any stakeholders.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was
selected by an in-house editor and fully peer-reviewed by external
reviewers. It is distributed in accordance with the Creative
Commons Attribution Non Commercial (CC BY-NC 4.0) license,
which permits others to distribute, remix, adapt, build upon this
work non-commercially, and license their derivative works on
different terms, provided the original work is properly cited and
the use is non-commercial. See: http://creativecommons.org/
licenses/by-nc/4.0/
Manuscript source: Invited manuscript
Correspondence to: Achim Elfering, PhD, Department of Work
and Organizational Psychology, University of Bern, Fabrikstrasse 8,
3000 Bern, Switzerland. achim.elfering@psy.unibe.ch
Telephone: +41-31-6313639
Received: March 9, 2016
Peer-review started: March 15, 2016
First decision: April 20, 2016
Revised: August 18, 2016
Accepted: August 30, 2016
Article in press: August 31, 2016
Published online: November 18, 2016
Abstract
AIM
To investigate the acute effects of stochastic resonance
whole body vibration (SR-WBV), including muscle rela-
xation and cardiovascular activation.
METHODS
Sixty-four healthy students participated. The participants
were randomly assigned to sham SR-WBV training at a
low intensity (1.5 Hz) or a verum SR-WBV training at a
higher intensity (5 Hz). Systolic blood pressure (SBP),
diastolic blood pressure (DBP), heart rate (HR) and self-
reported muscle relaxation were assessed before and
immediately after SR-WBV.
RESULTS
Two factorial analyses of variance (ANOVA) showed a
significant interaction between pre-
vs
post-SR-WBV
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DOI: 10.5312/wjo.v7.i11.758
World J Orthop 2016 November 18; 7(11): 758-765
ISSN 2218-5836 (online)
© 2016 Baishideng Publishing Group Inc. All rights reserved.
Randomized Controlled Trial
759 November 18, 2016
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Elfering A
et al
. Stochastic resonance whole body vibration training
measurements and SR-WBV conditions for muscle
relaxation in the neck and back [F(1,55) = 3.35,
P
=
0.048, η2 = 0.07]. Muscle relaxation in the neck and back
increased in verum SR-WBV, but not in sham SR-WBV. No
signicant changes between pre- and post-training levels
of SBD, DBD and HR were observed either in sham or
verum SR-WBV conditions. With verum SR-WBV, improved
muscle relaxation was the most signicant in participants
who reported the experience of back, neck or shoulder
pain more than once a month (
P
< 0.05).
CONCLUSION
A single session of SR-WBV increased muscle relaxation
in young healthy individuals, while cardiovascular load
was low. An increase in musculoskeletal relaxation in the
neck and back is a potential mediator of pain reduction in
preventive worksite SR-WBV trials.
Key words: Musculoskeletal system; Prevention; Blood
pressure; Heart rate; Low back pain
© The Author(s) 2016. Published by Baishideng Publishing
Group Inc. All rights reserved.
Core tip: This randomized controlled trial shows musculo-
skeletal relaxation to increase after application of a single
training of stochastic resonance whole body vibration (SR-
WBV). SR-WBV increased muscle relaxation especially in
those who suffered from musculoskeletal pain in the last
year. Participants reported improved muscular relaxation
while the cardiovascular activation as indicated by blood
pressure and heart rate was very low. In addition to
ergonomic interventions SR-WBV contributes to prevent
muscle related pain at work.
Elfering A, Burger C, Schade V, Radlinger L. Stochastic resonance
whole body vibration increases perceived muscle relaxation but
not cardiovascular activation: A randomized controlled trial. World
J Orthop
2016; 7(11): 758-765 Available from: URL: http://www.
wjgnet.com/2218-5836/full/v7/i11/758.htm DOI: http://dx.doi.
org/10.5312/wjo.v7.i11.758
INTRODUCTION
Whilst evidence for long-lasting vibration exposure
at work, as a risk factor for musculoskeletal disease
(MSD), is substantial[1], recent research also showed the
benecial training effects of brief vibration experiences[2].
It is noteworthy that it is low frequency vibration
exposure (5-12 Hz) that is more promising and seems
safer than high frequency exposure at 20 to 60 Hz[3,4].
Stochastic resonance whole body vibration training (SR-
WBV) consists of low frequency exposure and has been
shown to reduce pain in those with chronic MSD[5].
The outcome of SR-WBV at the worksite is promising.
Four weeks of SR-WBV were reported to increase
musculoskeletal well-being in the workers of a steel
manufacturing company[6], but also in employees that
engage in sedentary work, especially those who suffered
from back pain prior to SR-WBV[7]. The latest randomised
controlled trial with eight weeks of SR-WBV also showed
the positive effects of SR-WBV in the employees of a
university hospital, especially in those with baseline
health restraints[8]. In the same population, SR-WBV
was also shown to increase posture control, which was
assessed by mediolateral sway on a force plate before
and after the eight-week trial[9]. The positive effects
of SR-WBV were also shown in the musculoskeletal
function of young healthy adults[10], and one more study
confirmed electromyographically that activation of the
descending trapezius muscle decreased after SR-WBV,
while blood ow and skin temperature also increased in
this area, and the energy cost of SR-WBV was low[11].
A change in back muscle activation from induced SR-
WBV training for the sensorimotor system, and not
primarily from an increase in fitness, seemed to be
involved in the overall positive effects of SR-WBV on
musculoskeletal well-being and function[7]. Therefore,
it is a plus of SR-WBV that the self-reported physical
demands seemed to be small for most participants, and
no sweating was reported. Even so, not only the muscle
relaxation that followed the activation of the descending
trapezius muscle, but also the change in blood pressure
and heart rate from SR-WBV, should be evaluated to
estimate the overall demands of SR-WBV training. The
current randomized controlled trial tests the hypothesis
that 5Hz-SR-WBV improves muscle relaxation (H1),
and that 5Hz-SR-WBV triggers cardiovascular activation
(H2), whereas 1.5 Hz-SR-WBV (sham condition) has no
effect on muscle relaxation or cardiovascular activation.
Therefore, 5 Hz-SR-WBV should have the greatest effect
on muscle relaxation in those who reported back, neck or
shoulder pain in last 12 mo (H3). The test of the second
hypothesis is essential. Minimal cardiovascular activation
would allow individuals at modest cardiovascular risk to
perform SR-WBV.
How SR-WBV works
SR-WBV benefits from the effects of stochastic res-
onance by applying vibrations of low frequency with
a maximal degree of complexity and unpredictability.
Ward and colleagues defined stochastic resonance as
“a nonlinear cooperative effect wherein the addition
of a random process, or ‘noise to a weak signal, or
stimulus results in improved detectability or enhanced
information content in some response”[12]. SR-WBV
differs completely from simple frequency fast sinusoidal
vibrations, like the ones applied by the most common
and conventional sinusoidal vibration training devices.
During SR-WBV, the human body cannot anticipate the
upcoming vibration movements, and therefore, the body
is constantly challenged to adapt its neural and muscular
reactions and shows no muscular fatigue during the
application[13-16]. SR-WBV seems to provoke an interaction
of different types of neurophysiologic sensors and the
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adjustment of afferent and efferent signals, which
probably acts as exercise for the sensorimotor system[13].
The observed increase in strength is mainly attributed
to neural adaptation, which leads to improved inter-
and intramuscular coordination, which, in turn, allows
the increased activation of prime movers in specific
movements, and better coordination in the activation
of all relevant muscles[17] or a higher muscular activity
in insufficient muscles, when compared to sinusoidal
vibration[18]. A low risk of injury and only the rare
manifestation of side-effects make SR-WBV an attractive
preventive intervention[5,19].
MATERIALS AND METHODS
Ethics
The study was performed in consensus with all re-
quirement defined by the Swiss Society of Psychology.
The study was conducted with the understanding and the
consent of the human subject. The Ethical Committee
of the responsible University faculty has approved the
study.
Participants
Expecting a moderate effect size for the repeated me-
asures, within-between interaction and a requirement
of a 90% power to detect an existing difference, the
required sample size was 64 participants. Sixty-four
undergraduate and graduate students were asked for
participation and all agreed to participate (34 female
and 30 male psychology majors, mean age = 27.6
years, SD = 5.0 years). The inclusion criterion was acute
health status. The exclusion criteria for participation
were recorded anamnestically, and comprised acute,
past or chronic arthropathologies, troubles in the
cardiovascular system, psychopathology, spondylolysis,
spondylolisthesis, tumors, disc prolapse with neurological
failure, rheumatism, articular gout, osteoporosis, acti-
vated arthritis with inammatory signs, stage 4 arthritis,
fever, cold, etc. No participant had to be excluded from
the study. All participants nished the study protocol.
Procedure
The study was conducted at a University facility. The
participants completed a single SR-WBV training session.
A special device was applied for SR-WBV (©Zeptor med
plus Noise, FreiSwiss AG, Zurich, Switzerland). Its key
features were two independently and one-dimensional
(up/down) stochastically oscillating floorboards, with
two passive degrees of freedom (forward/backward and
right/left). Each SR-WBV session was supervised, and
the participants were instructed to stand in an upright
position on the footboards with their arms hanging loose
to the side and with slightly bent knees and hips (Figure
1). Both legs should have contact to the plates. It was
permitted to change the knee angle but participants
were instructed not to stand up straight because in that
position vibration is conducted to the head. Figure 1
was shown to demonstrate the posture to participants.
The participants were randomly allocated to SR-WBV
groups (5 Hz verum condition or 1.5 Hz sham condition).
The randomisation was based on the use of a list of
random numbers[20]. The session consisted of three
series of SR-WBV, which lasted one minute each, with
a one-minute break between them. The 5 Hz verum
condition was used as the minimum effective SR-WBV
stimulation loading parameter, while the 1.5 Hz sham
condition can be expected to have no training effect[10,21].
Participants were blind with respect to their training
frequency condition. The investigator did the setting of
the frequency before the training session started. The
setting-screen was additionally covered by a piece of
paper so that the participants never knew the exact
vibration frequency.
Blood pressure and heart rate
The blood pressure cuff was put into place at the
beginning of the session before the participants filled
out the questionnaire. Participants wore the ambulatory
blood pressure device (blood pressure monitor Spacelabs
© model 90207; readings taken by the Korotkoff
method) throughout the experimental session. Blood
pressure was recorded one minute before and after
the SR-WBV session. In an ambulatory blood pressure
assessment, the Spacelabs 90207 often is denoted as
the “gold standard”[22]. To ensure the comparability of
blood pressure levels measured during the presentations,
all analyses are based on data recorded in a sitting
position.
Muscular pain and relaxation assessment
Musculoskeletal pain was assessed with a question that
addressed musculoskeletal pain in the back or neck/
shoulders in the last 12 mo (never, less than monthly,
less than weekly, less than daily, daily). It is part of a
scale that measures psychosomatic complaints that
was developed by Mohr et al[23] based on the previous
work of Fahrenberg et al[24]. Muscular relaxation was
assessed by a short version of the self-administered
questionnaire of Burger et al[6] that was completed
Figure 1 Starting position on stochastic resonance whole body vibration
device.
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before and after SR-WBV. The participants were asked
to rate muscle relaxation on a 10-point Likert scale. The
question was introduced, “At the moment, how do you
rate your personal sensation in your muscles and joints
(back, shoulder and neck, leg muscles, etc.)?”, which
was followed by “Relaxation in the muscles and joints”,
and the corresponding 10-point rating scale from “no
relaxation” to “strongest imaginable relaxation”.
Statistical analysis
Self-reported muscle relaxation, systolic blood pressure
(SBP), diastolic blood pressure (DBP) and heart rate
(HR) were analysed in a two-factorial ANOVA, including
the repeated measurement (pre- vs post-session mea-
surement) of SBP, DBP, HR and self-reported muscle
relaxation as a within-subjects factor, and the SR-WBV
training group condition (verum: 5 Hz, sham: 1.5 Hz) as
a between factor.
We tested hypothesis 3 - expected gain in muscle
relaxation to be the largest in verum SR-WBV and among
those with musculoskeletal pain, compared with verum
SR-WBV with no pain, and sham SR-WBV with and
without pain - by planned contrasts as recommended
by Strube et al[25]. The change in muscle relaxation
(post-SR-WBV minus pre-SR-WBV) was the dependent
variable. P-values were two-tailed with α set to 5%.
RESULTS
Participant characteristics
Before the training study started, the participants reported
the frequency of musculoskeletal pain episodes in the
back, neck or shoulders in the last 12 mo. Thirteen
participants (20.3%) reported that they had never
experienced pain during this period of time. Fifteen
participants (23.4%) reported pain episodes less than
monthly, and 21 participants (32.8%) reported pain
episodes less than weekly. Ten participants (15.6%)
reported pain episodes that occurred every week, but
less than daily. Five participants (7.8%) experienced pain
every day in the last 12 mo. Sixty-four healthy students
participated in this study. Table 1 depicts the descriptive
study results. The 64 participants were randomly assigned
to SR-WBV conditions, and no significant differences
in musculoskeletal pain episodes in the back, neck or
shoulders in the last 12 mo were observed between the
groups of verum SR-WBV and sham SR-WBV (Table
1). Thirty-four participants were assigned to verum SR-
WBV, and 30 participants were assigned to sham-SR-
WBV. The verum and sham SR-WBV groups did not
differ significantly in any demographic characteristics or
in baseline muscle relaxation or DBD and HR. However,
the baseline and follow-up SBP was significantly higher
in verum SR-WBV than in sham SR-WBV (Table 1). Table
2 shows the correlations between study variables. Pain
episodes in the back, neck or shoulders in the last 12 mo
were negatively related to sex, showing higher pain in
women than in men. Fitness was negatively related to
pain episodes in the back, neck or shoulders.
SR-WBV and improved muscle relaxation (H1)
The ANOVA results for the test of the rst hypothesis are
shown in Table 3. A signicant interaction term indicated
that verum SR-WBV improved muscle relaxation, while
Table 1 Mean values of study variables in verum stochastic resonance whole body vibration and sham stochastic resonance whole
body vibration groups
Variable Verum-SR-WBV (5 Hz SR-WBV) (
n
= 34) Sham SR-WBV (1.5 Hz SR-WBV) (
n
= 30)
t P
Mean SD Mean SD
Systolic blood pressure
Pre-training 129.67 12.78 120.9 9.68 3.05 0.003
Post-training 126.97 11.54 120.57 10.43 2.32 0.024
Diastolic blood pressure
Pre-training 78.61 11.00 75.27 7.64 1.39 0.171
Post-training 79.00 8.92 75.13 8.37 1.78 0.080
Heart rate
Pre-training 71.09 12.03 69.1 15.67 0.57 0.572
Post-training 69.94 11.51 68.4 13.25 0.50 0.620
Muscle relaxation
Pre-training 6.47 2.06 6.87 2.47 0.70 0.488
Post-training 7.00 2.10 6.7 2.59 0.51 0.611
Age (yr) 27.76 3.70 27.4 6.15 0.28 0.7791
Sex 18 f, 16 m 16 f, 14 m
χ
2 = 0.001 0.975
BMI 22.58 2.59 21.68 2.80 1.34 0.187
Fitness 3.65 0.65 3.66 0.72 -0.05 0.963
Smoker (10 cigarettes or more) 12 (6) 7 (3)
χ
2 = 1.09 0.296
Smoking (cigarettes) 3.53 6.33 2.30 6.98 0.74 0.463
Cups of coffee before training 1.50 1.11 1.67 1.47 -0.52 0.608
Back, neck or shoulder 2.71 1.00 2.63 1.40 0.24 0.8151
pain in last 12 mo
1Corrected for unequal variances. BMI: Body mass index; SR-WBV: Stochastic resonance whole body vibration; f: Female; m: Male.
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no change appeared in sham SR-WBV [F(1,62) = 3.86,
P = 0.031, η2 = 0.069]. Figure 2 shows the change in
muscle relaxation in both study groups.
SR-WBV and increase in cardiovascular activation (H2)
In verum and sham SR-WBV, the mean levels in SBP,
DBP and HR were almost the same before and after SR-
WBV (Table 1). The ANOVAs of SBP, DBP and HR did
not show signicant interaction effects [SBP: F(1,61) =
1.92, P = 0.171, η2 = 0.030; DBP: F(1,61) = 0.07, P =
0.792, η2 = 0.001; HR: F(1,61) = 0.010, P = 0.919, η2
= 0].
SR-WBV and back, neck or shoulder pain in last 12 mo
(H3)
Verum SR-WBV was expected to have the greatest
effects on muscle relaxation in those who reported back,
neck or shoulder pain in last 12 mo. These individuals
should benefit more from 5Hz SR-WBV than those
without pain and those with and without pain in the
sham SR-WBV condition. Figure 3 shows the change
in the musculoskeletal relaxation for SR-WBV groups
separately, for those with and without back, neck or
shoulder pain in last 12 mo. As expected, the increase in
muscle relaxation was the greatest in those with pain in
the verum SR-WBV group, and was signicantly greater
than in all other groups, as shown in the planned contrast
analysis [F(1,60) = 5.30, P = 0.025, η2 = 0.081].
DISCUSSION
The current findings showed self-reported musculo-
skeletal relaxation increased significantly after verum
SR-WBV, but not after sham SR-WBV, while SBP, DBP
and HR did not change in either verum SR-WBV or sham
SR-WBV. The current results confirm a recent more
explorative investigation on acute effects of SR-WBV
that showed increased muscle relaxation measured by
electromyography and low cardiac activation measured
by heart rate variability[11]. Conrmation was important
Table 2 Correlations between study variables
Variables SR-WBV
condition
SBP
pre
SBP
post
DBP
pre
DBP
post
HR
pre
HR
post
Relax pre Relax
post
Age Sex BMI Fitness Smoking Coffee
SR-WBV Condition
SBP pre -0.36c
SBP post -0.28a 0.83e
DBP pre -0.18 0.63e 0.57e
DBP post -0.22 0.59e 0.71e 0.68c
HR pre -0.07 0.02 0.01 0.22 0.22
HR post -0.06 0.03 0.07 0.21 0.24 0.76e
Relaxation pre 0.09 0.02 0.22 -0.04 0.01 0.04 -0.01
Relaxation post -0.07 0.09 0.24 0.03 0.03 0.01 -0.04 0.84e
Age -0.04 0.36c 0.40c 0.24 0.23 -0.03 -0.11 0.26a 0.26a
Sex -0.01 0.26a 0.36c-0.07 0.05 -0.16 -0.1 0.28a 0.15 0.29a
BMI -0.17 0.08 0.14 -0.14 0 -0.32c-0.19 -0.01 0.02 0.15 0.45e
Fitness 0.01 0.15 0.19 -0.13 -0.2 -0.19 -0.16 0.41c 0.38c 0.30a 0.34c0.24
Smoking (number
of cigarettes)
-0.09 0.10 0.07 -0.12 0.06 0.25a 0.37c-0.01 -0.07 0.07 0.36c0.28a-0.02
Cups of coffee
before training
0.07 0.09 0.01 -0.01 0.01 0.07 0.16 -0.28a-0.28a 0.20 0.16 0.16 -0.18 0.33c
Back, neck or
shoulder pain in
last 12 mo
-0.03 -0.18 -0.30a -0.04 -0.14 -0.08 0.03 -0.55e-0.59e-0.09 -0.27a0.02 -0.26a-0.03 0.24
aP < 0.05, cP < 0.01, eP < 0.001: Correlations coefcients that signicantly differ from zero. SR-WBV: Stochastic resonance whole body vibration; SBP: Systolic
blood pressure; DBP: Diastolic blood pressure; HR: Heart rate.
Table 3 Results of two-factorial ANOVA
Sum of squares
df
Mean square
F P
Partial eta-square
Inner-subject effects
Pre- vs post-training (n = 64) 1.05 1 1.05 1.32 0.255 0.021
Training group (5 Hz vs 1.5 Hz) 3.86 1 3.86 4.85 0.031 0.073
Within subjects error 49.32 62 0.80
Between subjects effects
Constant 8.91 1 8.91 1.18 0.282 0.021
Training group (5 Hz vs 1.5 Hz) 0.74 1 0.74 0.01 0.931 0.000
Between subjects error 608.92 62 9.82
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because the previous investigation was based on a
comparably small sample (one third of the sample
size of the current study) and was based solely on a
repeated measurements design[11]. Hence, the current
randomized controlled trial increased the evidence that
one trial of SR-WBV has beneficial musculoskeletal
effects while cardiovascular load is moderate. Muscle
relaxation after SR-WBV prevents musculoskeletal
pain that may arise from consistently high muscle
tension[1]. Repeated SR-WBV may decrease muscle
tension and musculoskeletal pain. The present ndings
showed that participants who reported back, neck and
shoulder pain episodes in the last 12 mo were the main
beneficiaries of the overall positive effects of SR-WBV
on muscle relaxation. Using repeated SR-WBV Elfering
and colleagues found in a four-week worksite study
that SR-WBV was more clearly linked to reduced pain
in those who suffered from musculoskeletal pain prior
to training, while those who were pain-free benefited
less[15]. Thus, SR-WBV seems to have specic positive
effects on the neuro-muscular system, while the
absence of cardiovascular activation indicates that the
positive effects are unlikely to be mediated by changes
in overall tness.
Four and eight-week worksite training studies sho-
wed SR-WBV can easily be done before, during or after
work without having to change clothes or take a shower
afterwards[6-9]. Further, the low cardiovascular demands
of SR-WBV make SR-WBV a safe worksite prevention
tool.
Even so, the beneficial effects of SR-WBV seem to
contradict evidence of the harmful effects of vibration
exposure at work[1]. However, a distinction should
be made between SR-WBV and harmful vibration at
work[26]. The damaging effects of vibration at work are
caused by chronic exposure - with long exposure and
short rest cycles - to a rather regular vibration that is
often oscillating at a large amplitude or at frequencies of
mechanical resonance[27]. In contrast, SR-WBV training
efficiency and its therapeutic effects were summarised
recently[5,27]. SR-WBV may have risks and benets, and
both should be studied. A review of 112 studies on whole
body vibration reported very few side effects (0.00120%
in 104 studies that used sinus whole body vibration,
and 0.00069% in eight studies that used SR-WBV)[19].
More serious side effects have been exclusively found in
studies that used sinusoidal whole body vibration, but not
in studies that used SR-WBV[19]. SR-WBV seems to be a
safe training intervention with usually harmless adverse
effects when a careful evaluation of the medical history is
performed before SR-WBV to evaluate contraindications
or the potential risk factors of the subjects. In addition,
one should avoid unnecessarily intense exposure to keep
the risk of side-effects as low as possible. Therefore, we
did 60-s trainings, which is the shortest period known
to have a training effect. The next step in the evaluation
should test worksite SR-WBV to reduce MSD, but it
should also include an economic evaluation[28].
This study had an experimental design, and many
potential confounders were controlled by randomisation.
However, unexpectedly, baseline differences in SBP were
observed between the SR-WBV groups, with higher
SBP levels in verum SR-WBV. Thus, a regression to
mean levels cannot be excluded in SBP measurement
after SR-WBV. This is noteworthy; because of frequent
measurement artefacts, SBP and DBP could only be
measured after SR-WBV and not during SR-WBV. The
participants were blind with respect to their verum vs
sham SR-WBV condition. However, a blinding of the
primary investigator was not feasible.
The participants benefited from low frequency 5
Hz SR-WBV after three one-minute trials within one
10-min training session. The participants with a frequent
experience of back, neck and shoulder in last 12 mo had
improved muscular relaxation after SR-WBV, whilst blood
pressure levels and heart rate were nearly unchanged by
SR-WBV. In addition to ergonomic intervention, training
and participatory work redesign SR-WBV may help to
8
7
6
5
Muscle relaxation [0-10]
Pretraining Posttraining
EG [5 Hz]
CG [1.5 Hz]
Figure 2 Self-reported muscle relaxation before and after stochastic
resonance whole body vibration.
No pain episodes
(< 1/mo)
Pain episode
( 1/mo)
Back, neck or shoulder pain in last 12 mo
5 Hz verum SR-WBV
1.5 Hz verum SR-WBV
Change in self-reported muscle relaxation
[points post - pre SR-WBV]
1
0
-1
Figure 3 Change in self-reported muscle relaxation by stochastic
resonance whole body vibration and back, neck or shoulder pain in last
12 mo before stochastic resonance whole body vibration.
Elfering A
et al
. Stochastic resonance whole body vibration training
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prevent and reduce MSD at work.
COMMENTS
Background
Musculoskeletal pain is common and so far no experiment tested the acute
effects of a single stochastic resonance whole-body vibration training (SR-WBV)
on muscle relaxation and blood pressure.
Research frontiers
There is need for research on short, economic, and effective training
intervention. In this experiment, author(s) showed a single short SR-WBV
training to increase musculoskeletal relaxation.
Innovations and breakthroughs
The experiment showed benefits were higher in those with experience of
musculoskeletal pain while cardiovascular activation was low.
Applications
In previous works including 4 or even 8 wk of SR-WBV was found to improve
musculoskeletal pain and body balance, measured as self-report and as
recorded body sway on a balance platform. Improved body balance is
connected to a lower risk of slips and falls. Short trials of SR-WBV that amount
to less than 10 min can be done at a worksite without a change of clothes or
shoes. Cardiovascular demand with 5 Hz SR-WBV is low and permits SR-WBV
in the untrained or elderly workforce.
Terminology
SR-WBV constantly challenges the neuromusculoskeletal coordination to adapt
to unforeseeable change.
Peer-review
This is an interesting investigation and the authors are experts in stochastic
resonance whole body vibration.
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Elfering A
et al
. Stochastic resonance whole body vibration training
... Most patients with LBP have paravertebral muscle spasms [14,25]; vibration has been reported to relax muscles and relieve musculoskeletal pain caused by high muscle tone [26]. Studies on vibration exercise in LBP patients reported significant improvements in proprioception, following the stimulation of a proprioceptor such as the golgi tendon organ (GTO) [27]. ...
... Intervention was applied by modifying the exercise method used in the previous study [26]. The subjects, who were part of the Vibration (TT2590X7, TurboSonic Co., Seoul, Korea) group, performed six exercises (squat, bridge, single bridge, bridge and knee flex, side bridge, and plank) for 15 min on a Whole-body vibration machine (TT2590X7, TurboSonic Co., Seoul, Korea). ...
... First, vibration may have decreased pain by suppressing small fibers (A-δ or C fibers) from the pain signal transmitted to the central nervous system and activating large fibers (A-β fibers), closing the pain gate control [27,34,35]. Second, vibration may have improved pain resulting from muscle tension by relaxing the muscles [26]. Elfering et al. performed WBV training in healthy adults at high intensity (6 Hz) and low intensity (2 Hz) and reported that the activity of trapezius muscle was significantly increased at high intensity (high 5.71 ± 1.14% maximum voluntary contraction, MVC vs low 2.24 ± 0.48% MVC). ...
Article
Full-text available
There are many adolescent patients complaining of low back pain, but research on it is lacking. The purpose of this study was to investigate the effects of trunk stabilization exercise combined with vibration on the pain, proprioception, and kinematics of the lumbar spine (LS) during sit to stand (STS) in adolescent patients with nonspecific low back pain (LBP). Fifty LBP patients were recruited and were randomly divided into two groups: Vibration group (n = 25) and placebo group (n = 25). All participants underwent 36-sessions of training consisting of six exercises. The Vibration group provided vibration stimulation during exercise, but the placebo group did not. The Numeric Pain Rating Scale (NPRS) and digital dual inclinometer were used to measure pain intensity and proprioception. The kinematics of the lumbar spine during STS were measured by motion capture system. After training, the pain and proprioception in the vibration group improved significantly greater than the placebo group (p < 0.05). The mobility of LS (maximum range of motion, angular velocity, lumbar to hip movement ratios) and lumbar-hip coordination during STS in the vibration group were significantly improved compared to the placebo group (p < 0.05). Thus, trunk stabilization exercise combined with vibration may be used to improve the pain, proprioception, and kinematic of the lumbar spine during sit to stand in adolescent patients with LBP.
... As for back pain, an improvement was noticed in about 50% of women and, in the case of shoulder and hand pain, in about 31% of women experiencing such symptoms. Elfering et al. [25,26] also investigated the effect of SR-WBV on muscle pain. Participants of the study reported slight improvements immediately after the first stochastic resonance training session, which gradually progressed with further trainings. ...
Article
Full-text available
Background: During menopause, a woman’s health often deteriorates, and various methods are sought to prevent this decline. The aim of this study was to determine the influence of SR-WBV training on the health and wellbeing of women over 50 years of age. Methods: SR-WBV training was performed twice a week for six weeks using the SRT Zeptor® Medical-plus noise device. Forty-two women were trained on the D program (7–9 series, lasting 45–60 s each), and 23 women on the O program (9–11 series, lasting 50–60 s each). The frequency ranged from 2 to 8 Hz. Due to health problems, 12% of the women did not complete the study protocols. Results: The remaining women declared an improvement in mental state (51%), physical activity (68%), and general well-being (72%), as well as a reduction in lower limb pain (21%), back pain (14%), and urinary incontinence symptoms (17%). Conclusion: The benefits of SR-WBV training include improvement in general well-being and physical fitness, reduction of lower limb and back pain, and reduction of urinary incontinence symptoms. SR-WBV training can provoke or aggravate back pain and lower limb pain and cause other side effects, so the optimization of training parameters for SR-WBV is required.
... Prevented a shift in myofiber type during extended bed rest 86 Humans Increased isometric muscle strength, explosive muscle strength, and muscle mass in men older than 60 y of age 87 Human Caused muscle relaxation in the neck and back 88 Other effects ...
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Full-text available
Sound pressure waves surround individuals in everyday life and are perceived by animals and humans primarily through sound or vibration. When sound pressure waves traverse through a solid medium, vibration will result. Vibration has long been considered an unwanted variable in animal research and may confound scientific endeavors using animals. Understanding the characteristics of vibration is required to determine whether effects in animals are likely to be therapeutic or result in adverse biological effects. The eighth edition of the “Guide for the Care and Use of Laboratory Animals” highlights the importance of considering vibration and its effects on animals in the research setting, but knowledge of the level of vibration for eliciting these effects was unknown. The literature provides information regarding therapeutic use of vibration in humans, but the range of conditions to be of therapeutic benefit is varied and without clarity. Understanding the characteristics of vibration (eg, frequency and magnitude) necessary to cause various effects will ultimately assist in the evaluation of this environmental factor and its role on a number of potential therapeutic regimens for use in humans. This paper will review the principles of vibration, sources within a research setting, comparative physiological effects in various species, and the relative potential use of vibration in the mouse as a translational research model.
... Personen mit vergleichsweise geringem Entscheidungs-und Handlungsspielraum profitierten besonders (Elfering et al. 2014b). Das stochastische Resonanztraining erwies sich in mehreren Interventionsstudien als ein am Arbeitsplatz ökono-misch und einfach durchführbares Verfahren (Burger et al. 2012;Elfering et al. 2011Elfering et al. , 2013aElfering et al. , 2014cElfering et al. , 2016. ...
Chapter
Hohe Anforderungen, Hindernisse bei der Zielerreichung sowie mangelnde Gestaltungsmöglichkeiten sind heute kennzeichnend für den Arbeitsalltag vieler Erwerbstätiger. Dieses Kapitel gibt hierzu einen Überblick und zeigt den Zusammenhang solcher Arbeitsbedingungen mit wichtigen Gesundheitsindikatoren und daraus resultierenden Produktivitätsverlusten auf. Den Kosten des Stresses wird eine Nutzenkalkulation von stressreduzierenden Interventionen gegenübergestellt. Das Kapitel gibt einen Einblick in erfolgreiche Interventionsmöglichkeiten und schließt mit einem Ausblick auf stressrelevante Herausforderungen einer sich schnell wandelnden Arbeitswelt.
Article
[Purpose] The purpose of this study was to histopathologically determine whether treatment of the knee joint with vibrational stimulation during the cast fixation period could prevent changes in the infrapatellar fat pad. [Participants and Methods] Fourteen, 9-week-old, male Wistar rats were divided into 3 groups based on treatment strategies: Group C, control rats reared normally (n=5); Group I, rats that were immobilized (n=5); and Group V, rats treated with vibrational stimulation during immobilization (n=4). The right hindlimb was immobilized by cast fixation. In group V, vibration stimulation was applied for 15 minutes every day for 2 weeks. [Results] Adipose cells of different sizes and fibrosis were observed in groups I and V. The cross-sectional areas of fat cells were significantly different among the groups. [Conclusion] Vibrational stimulation may have a preventive effect on changes in fat cells associated with joint immobility.
Chapter
Hohe Anforderungen, Hindernisse bei der Zielerreichung sowie mangelnde Gestaltungsmöglichkeiten sind heute kennzeichnend für den Arbeitsalltag vieler Erwerbstätiger. Dieses Kapitel gibt hierzu einen Überblick und zeigt den Zusammenhang solcher Arbeitsbedingungen mit wichtigen Gesundheitsindikatoren und daraus resultierenden Produktivitätsverlusten auf. Den Kosten des Stresses wird eine Nutzenkalkulation von stressreduzierenden Interventionen gegenübergestellt. Das Kapitel gibt einen Einblick in erfolgreiche Interventionsmöglichkeiten und schließt mit einem Ausblick auf stressrelevante Herausforderungen einer sich schnell wandelnden Arbeitswelt.
Article
Full-text available
The objective of this article was to systematically review the effects of whole body vibration (WBV) loading parameters on the elderly, postmenopausal women and neurological patients. Ten databases were searched for clinical trials using WBV training in special populations. To assess the methodological quality, the PEDro score was used. To compare effects, effects were converted into percentage changes and effect sizes. Four clinical and 10 randomized clinical trial papers were included. The average PEDro score was 4.93 (±1.59). With 60-second intervention and 60-second rest periods, the most frequent vibratory stimulation loading parameters used were 3–6Hz and 3mm amplitude for multiple sclerosis and Parkinson’s disease patients, and 30Hz and 3–5mm amplitude for all other conditions. Balance, stability and functional performance significantly improved ( p <0.05) in all special population WBV intervention groups as compared with the control groups. Bone mass density and isometric leg strength improvements were also reported. WBV provides alternative and/or additional therapeutic interventions to improve physical and functional performance. The specific loading parameters and the value of WBV as compared with conventional interventions need to be the source of future research.
Article
Full-text available
To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV) training to identify possible explanations for preventive effects against musculoskeletal disorders. Twenty-three healthy, female students participated in this quasi-experimental pilot study. Acute physiological and psychological effects of SR-WBV training were examined using electromyography of descending trapezius (TD) muscle, heart rate variability (HRV), different skin parameters (temperature, redness and blood flow) and self-report questionnaires. All subjects conducted a sham SR-WBV training at a low intensity (2 Hz with noise level 0) and a verum SR-WBV training at a higher intensity (6 Hz with noise level 4). They were tested before, during and after the training. Conclusions were drawn on the basis of analysis of variance. Twenty-three healthy, female students participated in this study (age = 22.4 ± 2.1 years; body mass index = 21.6 ± 2.2 kg/m(2)). Muscular activity of the TD and energy expenditure rose during verum SR-WBV compared to baseline and sham SR-WBV (all P < 0.05). Muscular relaxation after verum SR-WBV was higher than at baseline and after sham SR-WBV (all P < 0.05). During verum SR-WBV the levels of HRV were similar to those observed during sham SR-WBV. The same applies for most of the skin characteristics, while microcirculation of the skin of the middle back was higher during verum compared to sham SR-WBV (P < 0.001). Skin redness showed significant changes over the three measurement points only in the middle back area (P = 0.022). There was a significant rise from baseline to verum SR-WBV (0.86 ± 0.25 perfusion units; P = 0.008). The self-reported chronic pain grade indicators of pain, stiffness, well-being, and muscle relaxation showed a mixed pattern across conditions. Muscle and joint stiffness (P = 0.018) and muscular relaxation did significantly change from baseline to different conditions of SR-WBV (P < 0.001). Moreover, muscle relaxation after verum SR-WBV was higher than after sham SR-WBV (P < 0.05). Verum SR-WBV stimulated musculoskeletal activity in young healthy individuals while cardiovascular activation was low. Training of musculoskeletal capacity and immediate increase in musculoskeletal relaxation are potential mediators of pain reduction in preventive trials.
Chapter
Epidemiology is research on the frequency and causes of diseases or syndromes in different populations. The baseline idea of epidemiology is that disease and causal factors are not distributed at random in human populations. Individuals who develop a disease are expected to be exposed to antecedent risk factors to a greater degree or for a longer time than are individuals who stay healthy. It is important to bear in mind that epidemiology estimates the association between risk factors and diseases in statistical terms.
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This paper shows an overview of biomechanical and physiological effects of mechanical oscillations in humans. The biological function of mechanical oscillations is a complex phenomenon that is analysed in various scientific fields. The basis of complexity is a large number of possible system states and solutions respectively which becomes obvious when one looks at the wide variety of scientific results. Regarding the effects of vibrations on coordination some analyses show that direct vibration transfer to muscles or tendons can lead to kinaesthetic illusions. Other studies found that low frequent whole-body-vibration can reduce coordinative deficits in Parkinson's disease patients. The diversity of scientific data also becomes obvious in the field of power and strength training. Results vary from slightly negative to highly positive effects of vibrations stimuli. The physiological background of the wide variety of results is based on one hand on multiple physiological levels that can be affected by mechanical oscillations and on the other hand on a non-linear structure of interaction between vibration stimuli and biological reaction.
Article
Background: When an organization performs an integrated analysis of risks through its Occupational Health and Safety Management System, several steps are suggested to address the implications of the identified risks. Namely, the organization should make a detailed analysis of the monetary impact for the organization of each of the preventive measures considered. However, it is also important to perform an analysis of the impact of each measure on society (externalities). Objective: The aim of this paper is to present a case study related to the application of the proposed economic evaluation methodology in a Hospital is presented. Methods: An analysis of the work accidents has been made. Three of the major types of accidents have been selected: needle stings, falls and excessive strain. Following the risk assessment, some preventive measures have been designed. Subsequently, the Benefit/Cost ratio (B/C) of these measures has been calculated, both in financial terms (from the organization's perspective) and in economic terms (including the benefits for the worker and for the Society). Results: While the financial ratio is only advantageous in some cases, when the externalities are taken into account, the B/C ratio increases significantly.CONCLUSIONS: It is important to consider external benefits to make decisions concerning the implementation of preventive measures in Occupational Health and Safety projects.
Article
Slip, trip, and fall injuries are frequent among health care workers. Stochastic resonance whole-body vibration training was tested to improve postural control. Participants included 124 employees of a Swiss university hospital. The randomized controlled trial included an experimental group given 8 weeks of training and a control group with no intervention. In both groups, postural control was assessed as mediolateral sway on a force plate before and after the 8-week trial. Mediolateral sway was significantly decreased by stochastic resonance whole-body vibration training in the experimental group but not in the control group that received no training (p < .05). Stochastic resonance whole-body vibration training is an option in the primary prevention of balance-related injury at work. [Workplace Health Saf 2014;62(5):187-196.].