Access to this full-text is provided by Wiley.
Content available from BioMed Research International
This content is subject to copyright. Terms and conditions apply.
Clinical Study
Comparison of Whole-Body Electromyostimulation versus
Recognized Back-Strengthening Exercise Training on Chronic
Nonspecific Low Back Pain: A Randomized Controlled Study
Anja Weissenfels ,
1
Nicolas Wirtz,
2
Ulrike D¨
ormann,
2
Heinz Klein¨
oder,
2
Lars Donath,
2
Matthias Kohl ,
3
Michael Fr¨
ohlich,
4
Simon von Stengel,
1
and Wolfgang Kemmler
1
1
Institute of Medical Physics, Friedrich-Alexander University of Erlangen-N¨urnberg, 91052 Erlangen, Germany
2
Institute of Training Science and Sport Informatics, German Sport University Cologne, 50933 K¨
oln, Germany
3
Department of Medical and Life Sciences, University of Furtwangen, 78054 Villingen-Schwenningen, Germany
4
Department of Sports Science, University of Kaiserslautern, 67663 Kaiserslautern, Germany
Correspondence should be addressed to Anja Weissenfels; anja.weissenfels@imp.uni-erlangen.de
Received 11 June 2019; Revised 16 August 2019; Accepted 10 September 2019; Published 29 September 2019
Academic Editor: Ayhan C¨omert
Copyright ©2019 Anja Weissenfels et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
Background. Low back pain (LBP) affects almost everyone at least once in their lifetime. Various meta-analyses show promising
effects on pain reduction for conventional exercise. However, the lack of time and, especially for pain patients, a fear of movement
(“kinesiophobia”) as well as functional limitations often oppose participation in such activities. In contrast, the advantage of novel
training technologies like whole-body electromyostimulation (WB-EMS) lies particularly in a joint-friendly, time-effective, and
highly customized training protocol and might be an alternative option for LBP patients. A meta-analysis of individual patient
data and a comparison of WB-EMS against a passive control group confirmed the proof principle. us, the aim of this
randomized controlled trial is to compare WB-EMS with a recognized back-strengthening exercise protocol to determine the
corresponding effects on chronic, nonspecific LBP in people suffering from this. Methods and Findings. is randomized,
controlled multicenter study is focused on novel and time-effective training technologies and LBP. In this contribution, the focus
is primarily on the comparison of WB-EMS against a comparable conventional exercise training (CT). One hundred ten
nonspecific chronic LBP patients, 40–70 years old, were randomly allocated to the intervention arms (WB-EMS: 55 vs. CT: 55).
Both groups completed a 12-week program (WB-EMS: 1 ×20 min/week vs. CT: 1 ×45 min/week) specifically dedicated to LBP.
e selection of the content of the active control group was based on the principles of WB-EMS training, which uses electrical
stimulation to train mainly strength and stabilization in a very short time. Exercises were similar in all groups, with the focus on
strengthening and stabilizing the trunk. Outcome measures were assessed by a four-week pain diary (before and during the last
four weeks of intervention) as well as an isometric maximum strength measurement of the trunk muscles at baseline and after 12
weeks of intervention. Primary study endpoint was average pain intensity at the lumbar spine. Secondary study endpoints were
maximum isometric strength of the back and the abdominals. e mean pain intensity of LBP decreased significantly in both
groups (WB-EMS: −22.3 ±20.9% vs. CT: −30.2 ±43.9%; p<0.001), however, without significant intergroup difference
(p�0.160). A similar result was observed for “maximum isometric strength of trunk muscles.” e increase in back strength
(WB-EMS: 15.6 ±24.9% vs. CT: 23.0 ±30.9%) was highly significant in both groups (p�0.001), and similar changes were
observed for the trunk flexors (WB-EMS: 17.6 ±24.8% vs. CT: 18.1 ±24.8%). Also, at the secondary endpoint, no significant
difference in pairwise comparison was observed in both cases (extension: p�0.297; flexion: p�0.707). Conclusion. In summary,
both, WB-EMS and conventional back-strengthening protocol are comparably effective in reducing nonspecific chronic LBP in
this dedicated cohort. e result is particularly positive in terms of time effectiveness and offers an adequate alternative for people
with limited time resources or other barriers to conventional training methods.
Hindawi
BioMed Research International
Volume 2019, Article ID 5745409, 9 pages
https://doi.org/10.1155/2019/5745409
1. Introduction
Due to changing living and working conditions [1, 2], the
incidence of nonspecific low back pain (LBP) is increasing
continuously worldwide [3]. e actual point prevalence
(32–40%) and lifetime prevalence (74–85%) of LBP are very
high [4]. However, LBP is not only a major individual health
problem but also has an economic impact due to temporary
or permanent inability to work and production losses [5].
us, more effort should be devoted to finding effective
therapies that best meet current individual needs. Indeed,
although present conservative therapies (e.g., resistance
training, stabilization exercises, flexibility training, and
aerobic exercises) demonstrate positive effects on LBP [6–8],
some important limitations might prevent or at least ag-
gravate the overall application in people with LBP. One
aspect is the lack of time, which limits participation in time-
consuming conventional exercise concepts [9]. In addition,
many patients with LBP develop “kinesiophobia,” i.e., a fear
of movement due to the inherent pain and are not willing to
start a traditional dynamic exercise program [10]. Lastly, the
observation in western societies that the majority of people
are unable or unwilling to exercise frequently [11] requires
the examination of optional training methods and tech-
nologies in the context of chronic unspecific LBP.
Due to their time-effectiveness, joint-friendly, and low
(voluntary) loading characteristics, novel exercise technol-
ogies like whole-body electromyostimulation (WB-EMS)
might be an option to time-consuming and intense back-
strengthening protocols. Addressing effectiveness, the re-
sults of a recent meta-analysis on WB-EMS trials [12]
summarized significant effects on LBP. e positive effect of
electrical whole-body stimulation on LBP was also con-
firmed in a previous study between WB-EMS and a passive
control group [13].
Under the premise that we expected the abovementioned
exercise protocol to be effective in significantly impacting
LBP, the aim of this study is to compare the effects of WB-
EMS with a recognized back exercise program in people with
nonspecific chronic LBP. ere are many effective ways to
reduce LBP, but we had to find a comparable form that
would match not only the content context of WB-EMS
(strengthening; stabilization) but also the time-effective
character with one training session per week. Although a
rough approach, the results of a meta-analysis [6] comparing
conservative exercise methods (standardized mean differ-
ence (SMD): 0.50) provided less favorable changes in LBP
compared with the WB-EMS specific meta-analysis of
Kemmler et al. [12] (SMD: 0.84). Based on this rationale, our
primary hypothesis is that WB-EMS is more effective in pain
reduction than the conservative training method (CT). Our
secondary hypothesis is that WB-EMS shows higher trunk
strength gains than CT.
2. Materials and Methods
2.1. Trial Design. After an initial comparison of WB-EMS
with a nonactive control group [13], this randomized,
controlled trial in a parallel group design examines the next
part of the multicenter study of the Institute of Medical
Physics (IMP), Friedrich-Alexander University Erlangen-
N¨
urnberg (FAU), and the German Sport University Cologne
(DSHS), both in Germany. e focus here is on the com-
parison of WB-EMS with a recognized strengthening
method in patients with chronic nonspecific LBP. Due to the
interrelated character of the multicenter study, the following
part shows similarities with the publication of the first
implementation of Weissenfels et al. [13]. e study con-
formed with the Helsinki Declaration “Ethical Principles for
Medical Research Involving Human Subjects” and was
verified by the Ethical Committee of the FAU (ethics ap-
plication no. 224_15b). e project was fully registered in the
German Clinical Trial Register (impact of alternative exer-
cise technologies on chronic low back pain in back pain
patients under special regard of its sustainability;
DRKS00009528). All study participants gave written consent
to do the testing and interventions. e study reporting is
based on the CONSORT 2010 guideline for randomized
studies with a parallel group design [14].
2.1.1. Participants. Participants between 40 and 70 years old
were recruited by personal letters, which included the most
important information as well as inclusion and exclusion
criteria. In order to take part in the study, the following
criteria had to be met: (a) 40–70 years old; (b) chronic pain
in the lumbar spine (at least 50 percent of the days of the last
three months); (c) no orthopedic diagnosis (unspecific type
of LBP); (d) average basal pain intensity (numbering rating
scale—NRS) ≥1); (e) no frequent intake of analgesics (>4
days/week); (f) no pharmacological therapy or diseases af-
fecting muscle metabolism (e.g., glucocorticoids); (g) no
contraindications for WB-EMS application (e.g., epilepsy,
cardiac pacemaker, thrombosis, and total endoprosthesis);
and (h) attendance in at least 10 of 12 units. A total of 12,000
letters were sent to which 650 persons responded. After
checking the eligibility of the study, 110 participants were
assigned to two intervention groups: WB-EMS (n�55) and
conventional training (CT) (n�55). e assignment was
randomized and stratified according to basal pain intensity
(NRS: 1–3, 4–6, 7–10). In Table 1, the baseline characteristics
of the subjects of all groups can be seen. e pain history of
the participants showed that the majority of the cohort
performed sitting or standing working activities (pre-
dominantly sitting: 41.8%; predominantly standing 40.0%),
while only a small proportion performed changing (15.4%)
or heavy physical work (2.8%). eir LBP, however, only
leads in 9.1% of the cases to inability to work. Looking at the
temporal history of the disease in 61.8% of the cases, the
beginning of LBP was more than 5 years ago, in 21.8%
between 2 and 5 years. e remaining participants reported
that they suffered LBP between 6 months and 2 years.
2.2. Intervention. e interventions described below took
place over a period of 12 weeks and were supervised by
certified instructors. To ensure that effects were not influ-
enced by other factors, participants were instructed to
maintain their usual lifestyle during the study.
2BioMed Research International
2.2.1. Whole-Body Electromyostimulation (WB-EMS).
WB-EMS is an innovative training technology that activates
muscle contractions by electrical impulses. In comparison to
the local version (e.g., TENS), WB-EMS addresses more
muscle groups at the same time so that the most important
parts are covered. Individual adjustment of the intensity is
possible via separate control buttons. More details about this
type of training can be found in several studies by Kemmler
et al. [15–17]. We applied a common stimulation protocol (see
Table 2) that is also used in commercial facilities. e main
structure of the training was formed by exercises specifically
dedicated to LBP (see Figure 1; see Table 2). Hence, no further
joints were stressed, and participants performed all exercises
with low amplitude. e WB-EMS training is based on
guidelines from miha bodytec (Gersthofen, Germany), and
therefore, a maximum of two individuals were trained once a
week at the same time per instructor [18].
An objective control of the stimulation intensity is not
possible with this type of training. Due to influencing factors,
such as individual pain sensation, body composition, or
humidity of the electrodes, the intensity can only be sub-
jectively assessed by the participants. For this purpose, the
BORG CR 10 scale was used, which converts the subjective
feeling of intensity into values between 0 “nothing at all” and
10 “extremely strong/maximal” [19]. With exception of the
first unit, participants were instructed to train at a rate of
perceived exertion (RPE) between “strong (5)” and “very
strong (7).” After a short time, the organism gets used to the
selected stimulation intensity so that a continuous adjust-
ment of the intensity has to take place during each session in
close cooperation with the participants. Exercises with
electrical stimulation can be very stressful for the organism,
which is why the guidelines prescribe a habituation phase of
several weeks [18]. During this phase, qualified instructors
increase training duration weekly from 12 minutes to the
final 20 minutes.
2.2.2. Conventional Training (CT). e CT program was
based on exercises dedicated to back strength/core stabili-
zation described by various meta-analyses [6, 7]. e de-
cision for a conventional back-strengthening training is
based on the comparability with WB-EMS, which averts
strengthening and stabilization via electrical impulses. Each
weekly session took 45 min: 15 min of aerobic warm up and
30 min circle training. e selection of the exercises is
according to the stimulation areas of WB-EMS and so we
focused on dynamic and static exercises for the trunk (see
Table 3). Detailed training content and exercise parameters
can be found in Table 3. In order to compare the intensity
between both intervention groups, the participants were also
instructed to perform exercise level between “strong (5)” and
“very strong (7)” on the BORG CR 10 scale. During each
session, a qualified instructor observed and corrected the
participants’ movement execution. A standardization of the
training was granted by audible support and announcements
of the working and resting times as well as station de-
scriptions on cards.
2.3. Outcomes
Primary endpoint
(i) Changes in average low back pain intensity from
baseline to 12-week follow-up
Secondary endpoint
(i) Changes in maximum isometric trunk extension
from baseline to 12-week follow-up
(ii) Changes in maximum isometric trunk flexion from
baseline to 12-week follow-up
2.4. Assessments. All tests were performed using the same
procedure and by the same researcher in each of the three
study periods. Baseline and follow-up tests took place at a
similar time of day (±60 min). To ensure proper standard-
ization, participants were requested to avoid severe physical
Table 1: Baseline characteristics of both intervention groups.
Variable CT (n�55) WB-EMS (n�55) p
Gender (m/f)
a
17/38 20/35 0.549
Age (years)
a
57.4 ±7.6 54.4 ±7.4 0.035
Height (m), m/f
b
1.83 ±4/1.66 ±7 1.82 ±5/1.67 ±7 0.825/0.440
Weight (kg), m/f
c
87.9 ±7.5/73.5 ±15.4 90.3 ±15.2/73.9 ±14.5 0.567/0.913
Total body fat (%), m/f
c
23.4 ±4.3/35.0 ±8.2 25.1 ±8.9/32.9 ±8.7 0.485/0.304
RMDQ (number of items)
a,d
4.8 ±3.3 5.6 ±3.9 0.277
Acute use of analgesics (n)
a
17 15 0.585
No regular exercise (n)
a
5 6 0.800
a
Assessed by baseline questionnaire.
b
Measured via stadiometer.
c
Measured via Bio-Impedance Analysis (DSM-BIA, InBody 770, Seoul, Korea).
d
RMDQ
measured functional limitations due to low back pain and consists of a 24-point scale.
Table 2: Exercises of WB-EMS intervention.
Exercise sequence for the WB-EMS group
e total duration of a unit are 20 minutes, with a habituation
phase of 4 weeks (12 to 20min/unit). Each session contains of 6
trunk specific exercises with 3 sets a 6 repetitions with the usual
stimulation parameters of WB-EMS (bipolar, 85 Hz, 350 μs, 6 sec
stimulation and 4 sec rest, 1 unit/week)
(1) Squat with latissimus pulleys
(2) Butterfly reverse (with angled arms)
(3) Straight pullovers with trunk flexion (lumberjacks)
(4) Standing trunk flexion (crunch)
(5) One-legged stand with biceps curl
(6) Side step with weight shift and biceps curl
BioMed Research International 3
activity 24 h prior to the assessments. ey were also asked to
fast for 3 h prior to the measurements.
All parameters for anthropometry were determined with
calibrated devices. To determine basal values and mor-
phological changes, body height was measured barefoot via
stadiometer. A Bio-Impedance Analysis (DSM-BIA, InBody
770, Seoul, Korea) detected weight and body composition.
Based on the electrical conductance of tissue, the device can
measure the distribution of body fat mass and muscle mass
in different segments (arms, trunk, and legs). In this case, it
operates with six frequency ranges between 1 and 1000 Hz.
e primary endpoint LBP intensity was protocolled
through a four-week pain diary prior to the intervention and
in the last four weeks of training. A numerical rating scale
(NRS) from 0 (no pain) to 10 (worst possible pain) was used
to indicate the daily pain intensity [20]. In addition to LBP
intensity, the duration of pain, special features, and the
intake of medication were also examined. A dedicated
questionnaire included other tools for back pain research
(German pain questionnaire, chronic pain grade (GCPS),
and Roland and Morris Disability Questionnaire (RMDQ))
[21–23]. To check influencing factors, baseline and follow-up
questionnaires included questions about diseases, medica-
tion, and lifestyle (changes).
For the functional measurement of the isometric trunk
strength, a Back-Check 607 (Dr. Wolff, Arnsberg, Germany)
was used. Depending on trunk flexion and extension, the
device is positioned differently and the recommendations of
the manufacture were observed. In both types of testing, all
participants were fixed at the level of iliac crest in an upright
position (0°) with angled knees (20°). To measure the
maximum trunk flexion strength (i.e., abdominal strength),
a measuring electrode was positioned at the level of the
sternum, while the maximum trunk extensor strength (i.e.,
back strength) was measured at scapula level. Based on the
tree test rounds, the highest value was included in the
analysis. In order to comply with quality criteria, reliability
(test-retest reliability; intraclass correlation (ICC)) for
maximum trunk extension in this cohort was 0.88 (95% CI:
0.82–0.93), whereas the value for maximum trunk flexion
was slightly lower at 0.86 (95% CI: 0.81–0.90) [13].
2.4.1. Sample Size, Randomization, and Blinding. e cal-
culation of the sample size is based on the results of a current
meta-analysis by Searle et al. [6] that examines the effects of
conventional types of exercise on LBP and on data from a
meta-analysis of individual patient data [6, 12]. Based on
these studies, we supposed a SMD of 0.55 for the primary
hypothesis using the 0–10 NRS. Addressing the core study
hypothesis by a t-test (i.e., differences between the WB-EMS
and the CT), 54 participants per group were required to
generate α�0.05 and β−1�0.80 (80% power).
In three conservative rounds (April 2017 to August
2018), a total number of 110 participants were balanced (1-1)
and randomly assigned into two equal groups by drawing
lots themselves (see Figure 2). ese were placed in opaque
plastic shells and stratified according to the NRS (0–3, 4–7,
7–10). In this context, it should be noted that neither par-
ticipants nor researchers were able to know the allocation
beforehand. us, the guidelines for allocation concealment
were realized consistent. While 30 participants (WB-EMS:
15 vs. CT: 15) were trained in the first round, the number of
persons in the following two rounds increased to 40 per
round (WB-EMS: 20 vs. CT: 20). After each balanced group
allocation (in total 55 participants per group), participants
were informed about the further study process and asked not
to change their usual lifestyle.
Due to the participation in different kinds of exercise
programs and for organizational reasons, a blinding of the
study participants, instructors, and primary researchers is
generally not possible for this kind of studies. erefore, we
concentrated on the blinding of the research assistants/
outcome assessors so that no correlation of the group status
was possible. In this case, the blinding was only partial.
2.5. Statistical Analyses. For the primary and secondary
endpoints, an intention-to-treat (ITT) analysis was used,
which included all participants no matter of compliance or
lost to follow-up. is type of analysis represents the “golden
standard” for clinical randomized trials (RCTs) [24]. e
calculation was done with Rstatistics software in combi-
nation with multiple imputation by Amelia II [25]. In this
Table 3: Exercises of conventional training group.
Exercise sequence for the CT group
In addition to a 15-minute warm up, the CT intervention is
constructed like a circle with 10 trunk specific exercises. e circle
is done twice with 50 sec work and 25 sec break between each
exercise. Every three weeks, the exercises slightly changed so that
the intensity is adjusted
(1) Seated rowing with cable pull
(2) Cable pulldown
(3) Crunch
(4) Plank
(5) Dynamic squat with arm movement
(6) Bird dog
(7) Side plank
(8) Static situp
(9) Back extensor
(10) Static hip bridge ⟶dynamic hip bridge
Figure 1: Alternative training technology whole-body electro-
myostimulation (WB-EMS).
4BioMed Research International
process, the entire data set was applied for multiple im-
putation, with imputation being repeated 100 times. A
dependent t-test was conducted to analyze within-group
differences. For this purpose, primary and secondary end-
points were statistically (Shapiro–Wilk test) and graphically
(QQ and box plots) checked for normal distribution before.
Independently of the endpoints mentioned, a Welch t-test
was used to calculate pairwise intergroup differences [26].
SPSS 25.0 (SPSS Inc, Chicago, IL) was selected for the
statistical calculation of baseline data, and all results were
presented as mean value (MV) and standard deviation (SD).
As usual, a statistical significance of p<0.05 was assumed for
the analysis.
3. Results
Fifteen participants dropped out after the start of the study
for various reasons: (1) injuries, diseases (n�9); (2) time
constraint (n�2); (3) disagreement with intervention
(n�1); (5) reason unknown (n�3). For the dropout rate no
significance between the groups was measured (p<0.784).
However, due to our ITT approach with missing data im-
putation, 55 participants per group were included in the
analysis. Except for age, no significant differences were
observed for baseline characteristics between WB-EMS and
CT group (see Table 1).
Attendance rate was high for both groups (WB-EMS:
92.0 ±7.4%; CT: 87.2 ±8.5%), with a significant intergroup
difference (p<0.004). All participants reported having
performed the intervention exactly according to the study
protocol. With the exception of one participant in the WB-
EMS group, no adverse or unintended side effects were
observed during the training sessions, and no participants
reported any WB-EMS or CT-related discomfort during or
after application/intervention. is person had to interrupt
the intervention due to gastritis, which was not caused by
WB-EMS.
e results of the primary study endpoint include a
highly significant decline in average pain intensity (WB-
EMS: −22.3 ±20.9%; CT: −30.2 ±43.9%; p≤0.001), how-
ever, without a significant intergroup difference (p�0.160)
(see Table 4). us, we have to revise our hypothesis that
WB-EMS shows better changes of average low back pain
intensity than in CT.
Maximum isometric trunk extensor strength signifi-
cantly increased (p≤0.001) in both study groups by
15.6 ±24.9% (WB-EMS) and 23.0 ±30.9% (CT), re-
spectively. Similar changes were observed for the trunk
flexors (WB-EMS: 17.6 ±24.8%; CT: 18.1 ±24.8%). Ab-
dominal maximum isometric strength also significantly
increased (p≤0.001); however, again we failed to detect
significant differences between the groups (extension:
p�0.297; flexion: p�0.707). us, we revised our sec-
ondary hypothesis that WB-EMS shows significantly better
developments of maximum isometric trunk strength com-
pared with CT.
Enrollment Assessed for eligibility (n = 144)
Randomized (n = 110)
Allocation
Follow-up aer
12 weeks
Analysis
Analysed via ITT (n = 55) Analysed via ITT (n = 55)
Excluded (n = 34)
Declined to participate (n = 12)
Other reasons (n = 22)
Allocated to WB-EMS (n = 55)
Received allocated intervention (n = 55)
Lost to follow-up (give reasons) (n = 7)
Injuries, diseases (n = 5)
Time issue (n = 1)
Disagreement with intervention (n = 1)
Lost to follow-up (give reasons) (n = 8)
Injuries, diseases (n = 4)
Time issue (n = 1)
Reason unknown (n = 3)
Allocated to CT (n = 55)
Received allocated intervention (n = 55)
(i)
(i)
(ii)
(iii)
(i)
(ii)
(iii)
(ii)
(i) (i)
Figure 2: CONSORT flow diagram of the study intervention.
BioMed Research International 5
With regard to lifestyle changes affecting LBP, additional
treatments were prohibited during the intervention. In total,
12 participants (WB-EMS: 4; CT: 8) started an additional
treatment during intervention, which mainly included
massage, physiotherapy, acupuncture, osteopathy, or sports
at work. On the other hand, four subjects stopped a pre-
viously started treatment: WB-EMS: 1; CT: 3. e number of
participants with acute intake of analgesics also changed. In
the WB-EMS group, it decreased from 15 to 9 persons and in
CT group from 17 to 8 persons. With regard to the pa-
rameters mentioned above, there are no significant differ-
ences between the groups (see Table 5).
4. Discussion
e aim of this study was to compare the effects of the novel
training technology WB-EMS on chronic low back pain with
a recognized back training program in a mixed cohort of
men and women between 40 and 70 years with nonspecific
chronic LBP. In summary, the results for average pain re-
duction and increase of muscle strength in trunk are highly
effective in both groups, however, without any significant
intergroup differences.
To our best knowledge to date, there is currently no other
trial that compares WB-EMS with a conventional method
with regard to the effect on nonspecific chronic LBP. In
contrast to the large amount of studies that focus on the
effect of conventional exercise on chronic LBP [6–8], there
are hardly any studies that focus on the effect of WB-EMS on
LBP. Apart from a published masters thesis [27], which
evaluates the effect of WB-EMS on LBP rather than an
experimental endpoint in a healthy clientele, only a meta-
analysis of individual patient data [12] addresses this issue.
In summary, after WB-EMS interventions ranging from 14
weeks to 12 months, pain intensity of lower back decreased
by 16.9% on a 7-level scale [12]. ese results are very similar
to the current study, while age (55.2 ±7.7 vs. 72.0 ±7.1
years), higher training frequency (1.0 vs. 1.5 sessions/week),
and LBP-specific vs. unspecific assessment tools might ex-
plain the slight difference between the present study and the
results of the meta-analysis.
Although several studies (e.g., [28–30]) demonstrated
the efficacy of conservative methods in the therapy of LBP,
some of the concepts applied differ considerably from the
design of the current trial and are therefore hardly com-
parable. Close to our study, Yang and Seo focused on
conservative exercise, especially, stabilization of the trunk, in
patients with nonspecific chronic LBP [31]. After 6 weeks of
intervention (3 session/week; 30 min per session), this group
achieved a pain reduction of 33.3%, measured via VAS.
Another study that applied a lumbar stabilization program
with 106 middle-aged workers for one year reported even
higher pain reduction rates of 44% that also determined via
VAS (7 days; 4 weeks) [32]. However, compared with the
present study, the training frequency was higher (1.0 vs. 2.0
sessions/week) and the intervention was conducted over a
much longer period of time (12 weeks vs. 12 month). Of
interest, the results after 6 months were much lower (VAS
past 7 days: −34.3%; VAS past 2 months: −22.2%), which
imply that the length of the intervention might be a relevant
predictor for the amount of pain reduction. Consequently,
we speculate that longer study periods will result in more
pronounced effects of pain reduction.
Summarizing the results of the secondary study endpoint
“maximum isometric trunk strength,” no significant in-
tergroup difference could be measured; however, the in-
crease in strength was highly significant across both groups.
Only a few studies verify this endpoint in patients with LBP;
their assessment methods differ greatly. erefore, a com-
parative discussion of our results with the present literature
is very limited. As to our best knowledge, this is the first
evidence-based study on WB-EMS and LBP, and we have to
refer to comparative studies with other clients or diseases.
Only one study [33] including elderly women (75 ±4 years)
with sarcopenia reviewed the change of maximum isometric
trunk extension after a WB-EMS intervention (1.5 sessions/
week; bipolar; 6 sec load—4 sec break; 85 Hz). After 12
months, maximum isometric trunk extensor strength in-
creased significantly (p≤0.001) by 10.1 ±12.7%. Despite a
longer intervention phase, the results of lumbar strength are
lower than in the present trial; however, the clientele of the
study of Kemmler et al. [33] was much older and suffered
from diseases that might confound the proper effect of WB-
EMS on muscle (strength). Most important, however, the
additionally performed movement patterns during WB-
EMS did not consistently focus on abdominal and back
strength during the latter study.
Studies focusing isolated lumbar extension resistance
training [28, 30] and particularly those that train on the
dedicated devices (e.g., MedX, Gainesville, FL) reported
almost twice as high strength gains compared with our more
conventional strengthening exercise program. Less specific,
Table 4: Results of the primary and secondary endpoint after 12 weeks of intervention.
CT MV ±SD (p) WB-EMS MV ±SD (p) Absolute difference MV (95% CI) p
Average pain intensity (4 weeks) (Index)
a
Baseline 2.81 ±1.34 2.69 ±1.52 — 0.689
Difference −0.85 ±0.97∗∗∗ −0.60 ±0.96∗∗∗ 0.25 (−0.10 to 0.60) 0.160
Maximum isometric trunk extension (kg)
Baseline 38.90 ±15.54 46.20 ±19.13 — 0.062
Difference 8.96 ±8.78∗∗∗ 7.19 ±8.82∗∗∗ 1.77 (−1.58 to 5.12) 0.297
Maximum isometric trunk flexion (kg)
Baseline 36.61 ±17.05 41.47 ±15.98 — 0.126
Difference 6.61 ±9.09∗∗∗ 7.30 ±9.05∗∗∗ 0.69 (−4.26 to 2.88) 0.707
a
Index from 0 (no pain) to 10 (worst possible pain). ∗∗∗p≤0.001.
6BioMed Research International
Moon et al. [34], who compared two lumbar exercise
protocols (isometric vs. dynamic), determined lumbar ex-
tension strength at different points of flexion angle (0°–72°)
using a specified assessment device (Med X, Gainesville, FL).
After 8 weeks of intervention (2 sessions/week; 60 min in
total; 14–16 exercises), maximum isometric extension
strength (0°position) increased by 30.0% in the dynamic and
48.5% in the isometric study group, with a significant in-
tergroup difference (p≤0.05) on this angle point [34].
In summary, independent of the exercise group, changes
in primary and secondary endpoints of the present trial are
very satisfying and range in the (upper) area of existing
studies. Since there are no comparable studies using this
design, it is not possible to discuss differences between the
active groups in more depth. Our finding of the favorable
effects of WB-EMS on chronic nonspecific LBP should
further result in a revision of the “negative recommenda-
tions” for electrotherapy according to the (German) Na-
tional Guideline for Back Pain [35].
Despite the current lack of evidence for a superiority to
conventional LBP programs, a major advantage of WB-EMS
is the time efficiency. Considering the net workout time, we
determined a highly significant difference between the
groups (WB-EMS: 200.1 ±22.6 min vs. CT: 471.1 ±45.8 min;
p�0.001). In other words, WB-EMS generated similar
effects on LBP as CT but in less time. Considering that time
constitutes a rather limited resource for many people, this
aspect might be the most striking argument for the appli-
cation of novel exercise technologies.
However, some limitations might decrease the scientific
evidence of our results. (1) One may argue that the com-
parison of two different back-specific training methods al-
ways entails limitations, but based on the aim to verify
options for conventional back exercises, the study represents
a realistic situation. Due to the strengthening and stabilizing
content of WB-EMS, the decision has been made in favor of
a back-specific-strengthening circle. In addition, similar
exercises were performed and comparable muscle groups
were trained. However, a comparison of identical protocols
with and without electrical stimulation is not effective. On
the one hand, this is because of the low intensity of the
exercises without electrical stimulation, low ROM, and low
loading time, which will not bring any benefit to the patients
and, on the other hand, to create a training situation which is
not related to real situations. In this sense, the comparison of
WB-EMS with CT should represent realistic and effective
training measures. (2) Another limitation that might in-
fluence the WB-EMS results is the low level of strain in-
tensity applied. Although the average intensity of RPE
5.8 ±1.1 reported by the participants was within our pre-
scribed target range (5 “hard” to 7 “very hard”), it is lower
than in most other WB-EMS trials [36]. We speculate that
generating higher strain intensities will result in higher
effects in LBP and particularly in strength changes; however,
it is difficult to implement this in a pain-sensitive cohort. (3)
As addressed above, a further reason that might lower the
results of this trial below comparative studies might be the
rather low inclusion criterion of NRS ≥1 that resulted in
average baseline pain intensity levels of 2.8 ±1.5. is,
however, is considerably lower than in comparable studies.
For comparison, Yang and Seo [31] listed even 5.4 ±1.4 on a
VAS 0–10 scale and other studies that used 0–100 VAS scales
observed average basal pain level of 34 ±18 [34] to 40 ±4
[37]. Under the premise that higher baseline values should
allow more pronounced exercise-induced reductions in low
back pain, our strategy to include subjects with lower levels
of unspecific chronic low back pain was less constructive.
Correspondingly, using baseline level of pain parameters as
inclusion criterion for further studies should be very care-
fully considered. (4) Based on the different intervention time
protocols per week (WB-EMS: 20 min vs. CT: 45 min), the
study may be said to have been arbitrarily designed to
advantage one of the groups. However, the trial was adjusted
as close as possible to reality using the current settings used
on the healthcare market. (5) Of course, the generalization of
our results to the entire cohort of people with LBP is limited.
In this study, we determined a positive effect of WB-EMS
and CT on chronic, nonspecific LBP in people between 40
and 70 years old, which constitutes the most relevant group
of LBP patients [38]. However, it would inappropriate to
directly transfer our results to (1) other age groups, (2) acute
pain periods or conditions, or (3) specific types of back pain
(e.g., vertebral fractures). With respect to the latter aspects,
exercise interventions might be even detrimental and con-
traindicated at least in the early stage of acute trauma-in-
duced LBP. Further, the intervention has to be much more
customized when addressing specific orthopedic indications
of LBP. However, although not reported here, we did not
detect gender or age-dependent differences in the efficacy of
WB-EMS or CT in our cohort. (6) ough the participants
were consistently encouraged to maintain their habitual
lifestyle, some participants reported changes with potential
effects on our study endpoints. While 12 participants started
a new therapy during intervention, four people stopped an
existing treatment. Nevertheless, since the corresponding
distribution within the study groups was quite similar, this
bias should not have relevantly affected our study results.
5. Conclusion
In summary, both types of exercise, WB-EMS and CT,
significantly reduce LBP intensity in people with chronic,
Table 5: Training characteristics and confounders with potential impact of the study endpoints.
Variable CT n�55 WB-EMS n�55 p
Dropout rate (n) 8 7 0.784
Attendance (%) 87.2 ±8.5 92.0 ±7.4 0.004
Total training time (min) 471.1 ±45.8 200.1 ±22.6 0.001
Changes of acute intake of analgesics (n) 17 ⟶8 15 ⟶9 0.791
BioMed Research International 7
nonspecific LBP, without relevant differences between the
interventions. Although we have to revise our hypothesis of
the corresponding superiority of the novel exercise tech-
nology WB-EMS, from a pragmatic point of view, these
results are more than welcome. Depending on time avail-
ability, medical cofactors, and personal preferences, patients
can individually decide which training suits them best. WB-
EMS offers an alternative and expands the range of effective
training options for LBP to those who cannot or do not want
to perform a conventional back-strengthening exercise
program. In addition, the results show that this alternative
training technology, which was originally developed for the
fitness sector, is absolutely relevant for the conventional
treatment of clinical diseases such as LBP.
Data Availability
Data are available upon request to the Institute of Medical
Physics of Friedrich-Alexander University Erlangen-N¨
urnberg
(anja.weissenfels@imp.uni-erlangen.de) for researchers who
meet the criteria for access to confidential data.
Disclosure
e funders had no role in study design, data collection and
analysis, decision to publish, or preparation of the manuscript.
Conflicts of Interest
e authors declare that the research was conducted in the
absence of any commercial or financial relationships that
could be construed as a potential conflicts of interest.
Acknowledgments
e present work was performed in (partial) fulfillment of
the requirements for obtaining the degree “Dr. rer. biol.
hum.” e authors would like to take this opportunity to
thank Dr. Britta Fraunberger and Dr. Norbert Grießinger
(Schmerzzentrum, Universit¨
atsklinik Erlangen) for their
support. e authors acknowledge the support of the
Deutsche Forschungsgemeinschaft (DFG) (Grant number: KE
2047/3–1). e authors also acknowledge the support of the
Friedrich-Alexander-University Erlangen-N¨
urnberg (FAU)
within the funding programme “Open Access Publishing.”
References
[1] H. Heneweer, L. Vanhees, and H. S. Picavet, “Physical activity
and low back pain: a U-shaped relation?,” Pain, vol. 143, no. 1-
2, pp. 21–25, 2009.
[2] A. G. Knuth, G. Bacchieri, C. G. Victora, and P. C. Hallal,
“Changes in physical activity among Brazilian adults over a 5-
year period,” Journal of Epidemiology & Community Health,
vol. 64, no. 7, pp. 591–595, 2010.
[3] J. K. Freburger, G. M. Holmes, R. P. Agans et al., “e rising
prevalence of chronic low back pain,” Archives of Internal
Medicine, vol. 169, no. 3, pp. 251–258, 2009.
[4] C. O. Schmidt, H. Raspe, M. Pfingsten et al., “Back pain in the
German adult population: prevalence, severity, and
sociodemographic correlates in a multiregional survey,”
Spine, vol. 32, no. 18, pp. 2005–2011, 2007.
[5] C. M. Wenig, C. O. Schmidt, T. Kohlmann, and B. Schweikert,
“Costs of back pain in Germany,” European Journal of Pain,
vol. 13, no. 3, pp. 280–286, 2009.
[6] A. Searle, M. Spink, A. Ho, and V. Chuter, “Exercise in-
terventions for the treatment of chronic low back pain: a
systematic review and meta-analysis of randomised controlled
trials,” Clinical Rehabilitation, vol. 29, no. 12, pp. 1155–1167,
2015.
[7] R. Gordon and S. Bloxham, “A systematic review of the effects
of exercise and physical activity on non-specific chronic low
back pain,” Healthcare, vol. 4, no. 2, p. 22, 2016.
[8] R. Shiri, D. Coggon, and K. Falah-Hassani, “Exercise for the
prevention of low back pain: systematic review and meta-
analysis of controlled trials,” American Journal of Epidemi-
ology, vol. 187, no. 5, pp. 1093–1101, 2018.
[9] S. Korsch, D. Herbold, M. Wiezoreck et al., “F¨orderfaktoren,
barrieren und barrierenmanagement zur umsetzung
gesundheitsf¨orderlicher verhaltensweisen von rehabilitanden
mit chronischem r¨uckenschmerz—eine qualitative analyse,”
Die Rehabilitation, vol. 55, no. 4, pp. 210–216, 2016.
[10] C. L¨uning Bergsten, M. Lundberg, P. Lindberg, and B. Elfving,
“Change in kinesiophobia and its relation to activity limita-
tion after multidisciplinary rehabilitation in patients with
chronic back pain,” Disability and Rehabilitation, vol. 34,
no. 10, pp. 852–858, 2012.
[11] A. R¨utten, K. Abu-Omar, T. Lampert, and T. Ziese,
“K¨orperliche aktivit¨at (physical activity),” Report, Statis-
tisches Bundesamt, Wiesbaden, Germany, 2005.
[12] W. Kemmler, A. Weissenfels, M. Bebenek et al., “Effects of
whole-body electromyostimulation on low back pain in
people with chronic unspecific dorsal pain: a meta-analysis of
individual patient data from randomized controlled WB-EMS
trials,” Evidence-Based Complementary and Alternative
Medicine, vol. 2017, Article ID 8480429, 8 pages, 2017.
[13] A. Weissenfels, M. Teschler, S. Willert et al., “Effects of whole-
body electromyostimulation on chronic nonspecific low back
pain in adults: a randomized controlled study,” Journal of
Pain Research, vol. 11, pp. 1949–1957, 2018.
[14] D. Moher, S. Hopewell, K. F. Schulz et al., “CONSORT 2010
explanation and elaboration: updated guidelines for reporting
parallel group randomised trials,” BMJ, vol. 340, no. 1, p. c869,
2010.
[15] W. Kemmler and S. von Stengel, “Whole-body electro-
myostimulation as a means to impact muscle mass and ab-
dominal body fat in lean, sedentary, older female adults:
subanalysis of the TEST-III trial,” Clinical Interventions in
Aging, vol. 8, pp. 1353–1364, 2013.
[16] W. Kemmler, A. Grimm, M. Bebenek, M. Kohl, and S. von
Stengel, “Effects of combined whole-body electro-
myostimulation and protein supplementation on local and
overall muscle/fat distribution in older men with sarcopenic
obesity: the randomized controlled franconia sarcopenic
obesity (FranSO) study,” Calcified Tissue International,
vol. 103, no. 3, pp. 266–277, 2018.
[17] W. Kemmler and S. von Stengel, “Alternative exercise tech-
nologies to fight against sarcopenia at old age: a series of
studies and review,” Journal of Aging Research, vol. 2012,
Article ID 109013, 8 pages, 2012.
[18] W. Kemmler, M. Froehlich, S. Von Stengel, and H. Klein ¨
oder,
“Whole-body electromyostimulation—the need for common
sense! Rationale and guideline for a safe and effective
8BioMed Research International
training,” Deutsche Zeitschrift f¨
ur Sportmedizin, vol. 2016,
no. 9, pp. 218–221, 2016.
[19] E. Borg and L. Kaijser, “A comparison between three rating
scales for perceived exertion and two different work tests,”
Scandinavian Journal of Medicine and Science in Sports,
vol. 16, no. 1, pp. 57–69, 2006.
[20] M. von Korff, M. P. Jensen, and P. Karoly, “Assessing global
pain severity by self-report in clinical and health services
research,” Spine, vol. 25, no. 24, pp. 3140–3151, 2000.
[21] B. W. Klasen, D. Hallner, C. Schaub, R. Willburger, and
M. Hasenbring, “Validation and reliability of the German
version of the chronic pain grade questionnaire in primary
care back pain patients,” Psycho-Social-Medicine, vol. 1, 2004.
[22] M. Roland and R. Morris, “A study of the natural history of
back pain,” Spine, vol. 8, no. 2, pp. 141–144, 1983.
[23] H. R. Casser, M. H¨uppe, T. Kohlmann et al., “Deutscher
schmerzfragebogen (DSF) und standardisierte dokumenta-
tion mit KEDOQ-schmerz,” Der Schmerz, vol. 26, no. 2,
pp. 168–175, 2012.
[24] J. Lewis and D. Machin, “Intention to treat—who should use
ITT?,” British Journal of Cancer, vol. 68, no. 4, pp. 647–650,
1993.
[25] J. Honaker, G. King, and M. Blackwell, “Amelia II: a program
for missing data,” Journal of Statistical Software, vol. 45, no. 7,
pp. 1–47, 2011.
[26] J. Barnard and D. B. Rubin, “Miscellanea. Small-sample de-
grees of freedom with multiple imputation,” Biometrika,
vol. 86, no. 4, pp. 948–955, 1999.
[27] J. Vatter, Elektrische Muskelstimulation als Ganzk¨orper-
training—Multicenterstudie zum Einsatz von Ganzk¨
orper-
EMS im Fitness-Studio, AVM-Verlag, Munich, Germany,
2010.
[28] J. Rittweger, K. Just, K. Kautzsch, P. Reeg, and D. Felsenberg,
“Treatment of chronic lower back pain with lumbar extension
and whole-body vibration exercise,” Spine, vol. 27, no. 17,
pp. 1829–1834, 2002.
[29] G. F. Maddalozzo, B. Kuo, W. A. Maddalozzo, C. D. Maddalozzo,
and J. W. Galver, “Comparison of 2 multimodal interventions
with and without whole body vibration therapy plus traction on
pain and disability in patients with nonspecific chronic low back
pain,” Journal of Chiropractic Medicine, vol. 15, no. 4, pp. 243–
251, 2016.
[30] J. Steele, S. Bruce-Low, D. Smith, D. Jessop, and N. Osborne,
“A randomized controlled trial of limited range of motion
lumbar extension exercise in chronic low back pain,” Spine,
vol. 38, no. 15, pp. 1245–1252, 2013.
[31] J. Yang and D. Seo, “e effects of whole body vibration on
static balance, spinal curvature, pain, and disability of patients
with low back pain,” Journal of Physical erapy Science,
vol. 27, no. 3, pp. 805–808, 2015.
[32] J. Suni, M. Rinne, A. Natri, M. P. Statistisian, J. Parkkari, and
H. Alaranta, “Control of the lumbar neutral zone decreases
low back pain and improves self-evaluated work ability,”
Spine, vol. 31, no. 18, pp. E611–E620, 2006.
[33] W. Kemmler, M. Bebenek, K. Engelke, and S. von Stengel,
“Impact of whole-body electromyostimulation on body
composition in elderly women at risk for sarcopenia: the
training and electrostimulation trial (TEST-III),” Age, vol. 36,
no. 1, pp. 395–406, 2014.
[34] H. J. Moon, K. H. Choi, D. H. Kim et al., “Effect of lumbar
stabilization and dynamic lumbar strengthening exercises in
patients with chronic low back pain,” Annals of Rehabilitation
Medicine, vol. 37, no. 1, pp. 110–117, 2013.
[35] J. F. Chenot, B. Greitermann, B. Kladney, F. Petzke,
M. Pfingsten, and S. G. Schorr, “Clinical practice guideline:
non-specific low back pain,” Deutsches Aerzteblatt Online,
vol. 114, pp. 883–890, 2017.
[36] W. Kemmler, A. Weissenfels, S. Willert et al., “Efficacy and
safety of low frequency whole-body electromyostimulation
(WB-EMS) to improve health-related outcomes in non-ath-
letic adults. A systematic review,” Frontiers in Physiology,
vol. 9, p. 573, 2018.
[37] N. Gusi, B. del Pozo-Cruz, M. A. Hernandez Mocholi,
J. C. Adsuar, J. A. Parraca, and I. Muro, “Effects of whole body
vibration therapy on main outcome measures for chronic
non-specific low back pain: a single-blind randomized con-
trolled trial,” Journal of Rehabilitation Medicine, vol. 43, no. 8,
pp. 689–694, 2011.
[38] D. Hoy, C. Bain, G. Williams et al., “A systematic review of the
global prevalence of low back pain,” Arthritis & Rheumatism,
vol. 64, no. 6, pp. 2028–2037, 2012.
BioMed Research International 9
Content uploaded by Michael Fröhlich
Author content
All content in this area was uploaded by Michael Fröhlich on Sep 29, 2019
Content may be subject to copyright.
