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Research Article
Effects of Whole-Body Electromyostimulation versus
High-Intensity Resistance Exercise on Body Composition and
Strength: A Randomized Controlled Study
Wolfgang Kemmler,1Marc Teschler,1Anja Weißenfels,1Michael Bebenek,1
Michael Fröhlich,2Matthias Kohl,3and Simon von Stengel1
1Institute of Medical Physics, Friedrich-Alexander University Erlangen-N¨
urnberg, 91052 Erlangen, Germany
2Department of Sports Science, University of Kaiserslautern, 67663 Kaiserslautern, Germany
3Department of Medical and Life Sciences, University of Furtwangen, 78048 Schwenningen, Germany
Correspondence should be addressed to Wolfgang Kemmler; wolfgang.kemmler@imp.uni-erlangen.de
Received November ; Revised January ; Accepted January
Academic Editor: omas Lundeberg
Copyright © Wolfgang Kemmler 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.
High-intensity (resistance) exercise (HIT) and whole-body electromyostimulation (WB-EMS) are both approaches to realize time-
ecient favorable changes of body composition and strength. e purpose of this study was to determine the eectiveness of WB-
EMS compared with the gold standard reference HIT, for improving body composition and muscle strength in middle-aged men.
Forty-eight healthy untrained men, – years old, were randomly allocated to either HIT ( sessions/week) or a WB-EMS group
( sessions/ weeks) that exercised for weeks. HIT was applied as “single-set-to-failure protocol,” while WB-EMS was conducted
with intermittent stimulation ( s WB-EMS, s rest; Hz, ms) over minutes. e main outcome parameters were lean body
mass (LBM) as determined via dual-energy X-ray absorptiometry and maximum dynamic leg-extensor strength (isokinetic leg-
press). LBM changes of both groups (HIT . ±.% versus WB-EMS 0.93 ± 1.15%) were signicant (𝑝 = .001); however, no
signicant group dierences were detected (𝑝 = .395). Leg-extensor strength also increased in both groups (HIT 12.7 ± 14.7%,
𝑝 = .002,versusWB-EMS7.3 ± 10.3%, 𝑝 = .012) with no signicant (𝑝 = .215) between-group dierence. Corresponding
changes were also determined for body fat and back-extensor strength. Conclusion. In summary, WB-EMS can be considered as
a time-ecient but pricy option to HIT-resistance exercise for people aiming at the improvement of general strength and body
composition.
1. Introduction
Time constraints are frequently reported as the main hin-
drance for frequent exercise; thus, time-saving exercise pro-
tocolsareattractivetopeopleseekingtoincreasetheirperfor-
mance, attractiveness, and health. With respect to resistance
exercise, low volume, high-intensity training (HIT) protocols
seem to be the most time-ecient method to improve mus-
cle mass and strength, independent of the ongoing debate
whether resistance exercise with higher volume may be
more eective in general [–]. However, alternative training
technologies tailored to commercial applications may dispute
this position. is includes in particular whole-body elec-
tromyostimulation (WB-EMS), which is becoming increas-
ingly popular in Europe. Unlike the well-known local EMS
application, WB-EMS technology is able to stimulate all the
main muscle groups with dedicated intensity simultaneously.
HIT and WB-EMS are oen regarded as being similarly time
ecient and safe; however, the few studies comparing the
eects of both methods on muscle mass and/or strength did
not show consistent results [–]. Nevertheless, commercial
suppliers advertise “outcome eects” of up to -fold higher
compared with conventional resistance exercise training. is
promise is, however, primarily based on the misinterpretation
Hindawi Publishing Corporation
Evidence-Based Complementary and Alternative Medicine
Volume 2016, Article ID 9236809, 9 pages
http://dx.doi.org/10.1155/2016/9236809
Evidence-Based Complementary and Alternative Medicine
Assessed for eligibility: n = 67
Excluded: n = 19
Not meeting inclusion criteria: n = 10
(i) Male, 30–50 years old: n = 3
(ii) “Untrained status”: n = 3
(iii) “Conditions that prevent WB-EMS”: n = 1
(iv) Absence for ≥2 weeks during intervention: n = 3
Declined to participate: n = 9
Randomized: n = 48
Refused to participate in the allocated group: n = 2
High intensity training (HIT): n = 23
Received allocated intervention: n = 23
Electromyostimulation (WB-EMS): n = 23
Received allocated intervention: n = 23
“Lost to follow-up”: n = 3
(i) Moved away: n = 1
(ii) Withdrawn due to time constraints: n = 2
“Lost to follow-up”: n = 2
(i) Moved away: n = 1
(ii) Severe discomfort during WB-EMS: n = 1
Analyzed (“completer analysis”)
HIT: n = 20 WB-EMS: n = 21
F : Flowchart of the study.
of very pronounced creatine-kinase (CK) peaks aer (too)
intense initial WB-EMS application [, ], whereas data that
clearly conrm the superiority of WB-EMS with respect to
relevant outcomes (i.e., lean body mass, strength) are still
lacking.
To estimate the comparative relevance of WB-EMS for
improving body composition and muscle strength, we com-
pared WB-EMS with the comparably time-ecient gold
standard reference “HIT.” In order to conclude this issue,
we conducted a randomized controlled trial with healthy
but untrained males, – years old, aiming to improve
their physical tness and body composition. Based on the
results of previous HIT [] and WB-EMS [, , ] studies,
our primary hypothesis was that HIT exercise training was
signicantly more eective for improving muscle mass and
maximum strength compared with WB-EMS.
2. Methods
e aim of the study was to compare the eects of HIT-
resistance training versus WB-electromyostimulation on
body composition and strength in healthy but untrained
middle-aged males living in the area of Herzogenaurach
(Northern Bavaria, Germany). To adequately address our
hypothesis, we conducted a -week single-blinded (in this
section) randomized controlled exercise trial, using a parallel
group design (Figure ). e trial was planned and conducted
by the Institute of Medical Physics, University of Erlangen
(FAU), Germany. e study complied with the Declaration of
Helsinki “Ethical Principles for Medical Research Involving
HumanSubjects”andwasapprovedbytheethicscommittee
of the FAU (Ethikantrag b) and the Federal Bureau of
Radiation Protection (Z-/--). All the study
participants gave written informed consent prior to study
participation.
e study was registered under clinicaltrials.gov
(NCT). Aer the commencement of the trial, no
furtherchangesweremadetothetrialprotocol.Weadhered
to the Consolidated Standards of Reporting Trial (CON-
SORT) for reporting (randomized) clinical trials [].
2.1. Participants. Figure gives the participant ow of the
study. Using the public register, , male subjects between
and years old living in the area of Herzogenaurach,
Germany, were contacted in two blocks (September and
November ). Personalized letters gave detailed study
information including the most relevant eligibility criteria for
the study. Sixty-seven males responded and were assessed for
eligibility. Applying our inclusion criteria of (a) male, –
years old; (b) “untrained status” dened as no regular
resistance exercise training (< session/week) and less than an
average of min exercise/week at all; (c) lack of pathological
changes of the muscle or heart or inammatory diseases;
(d) lack of medication/diseases aecting muscle metabolism;
(e) conditions that prevent WB-EMS (e.g., epilepsy, cardiac
pacemaker); and (f) absence of less than weeks during the
interventional period led to a total of subjects being eligi-
ble. Aer informative meetings presenting the detailed study
design, interventions, and measurements, nine subjects with-
drew.emainreasonsforwithdrawalwereunwillingnessto
Evidence-Based Complementary and Alternative Medicine
T : Baseline characteristics of the participants of the HIT and
WB-EMS group.
Variabl e HIT
𝑛=23 WB-EMS
𝑛=23 Dierence
(𝑝)
Age [years]a. ±. . ±. .
Body height [cm] . ±. . ±. .
Body weight [kg] . ±. . ±. .
BMI [kg/m2] . ±. . ±. .
Total body fat DXA [%] . ±. . ±. .
Physical activity [index]a. ±. . ±. .
Exercise volume
[min/week] . ±. . ±. .
Energy intake [kcal/d]b ± ± .
Protein intake [g/kg/d]b. ±. . ±. .
Alcohol [g/d]b. ±. . ±. .
Smoker [𝑛].
aSelf-rated physical activity score ( to , : very low; : very high) [];
bassessed by a -day dietary protocol and analyzed using the “Freiburger
Ern¨
ahrungsprotokoll” (Freiburger Nutrition Protocol, Nutri-Science, Ger-
many).
join the randomization procedure (𝑛=5) and/or to conduct
the WB-DXA assessment (𝑛=2). In order to increase com-
pliance with the group allocation, the remaining subjects
were randomly allocated to one of the two study groups,
(a) high-intensity training (HIT) group and (b) whole-body
electromyostimulation (WB-EMS) group, by drawing lots. In
detail, each of the lots was placed in intransparent plastic
shells (“Kinder Eggs,” Ferrero, Italy) and placed in a bowl
so that participants and researchers never knew the alloca-
tion. Although subjects were requested to be free for both
methods, two subjects allocated to the HIT-study arm imme-
diately withdrew aer randomization. In order to generate
comparable baseline group sizes, however, the randomization
sequence was correspondingly corrected by replacing a WB-
EMS lot by a HIT lot. us, HIT and WB-EMS group
subjects each embarked on the exercise program. All study
participants were requested to maintain their physical activity
and exercise habits during the study period.
Table gives baseline characteristics of the participants.
Randomization was eective; parameters that may have
confounded our results did not vary signicantly between the
groups.
2.2. Procedures
Main outcome parameters are as follows:
(i) Total lean body mass (LBM) as assessed by whole-
body dual-energy X-ray absorptiometry (WB-DXA).
(ii) Maximum dynamic leg-extensor strength as assessed
by an isokinetic leg-press device.
Secondary outcome parameters are as follows:
(i) Total body fat as assessed by WB-DXA.
(ii) Maximum isometric back-extensors strength as
assessed by an isometric test device.
2.3. Measurements. Each participant was tested at baseline
andfollow-upbythesameresearcheratthesametimeof
the day (± hour). All follow-up tests were conducted aer
one week of rest (week ). Tests were performed on one
day within min. Assessments were determined in a
(semi)blinded mode. Accordingly, testing sta and outcome
assessors were unaware of the participant status (i.e., WB-
EMSorHIT)andwerenotallowedtoask.
2.3.1. Anthropometry. Body height, weight, and waist cir-
cumference were measured by calibrated devices. Body Mass
Index was calculated by weight (kg)/height (m2). Total and
regional body composition was determined by dual-energy
X-ray absorptiometry (QDR a, Discovery Upgrade;
Hologic, USA) using the default standard protocols of the
manufacturer. Two researchers analyzed all the scans inde-
pendently. Interrater reliability (intraclass correlation, ICC)
for LBM was ..
2.3.2. Strength Parameters. Maximum strength of the leg
extensors was determined using a ConTrex isokinetic leg-
press (Physiomed, Laipersdorf, Germany). Bilateral concen-
tric leg extension (and exion) was performed in a sitting,
slightly supine position (∘), supported by chest and hip
straps. ROM was selected between ∘and ∘(knee angle),
with the ankle exed ∘and positioned on a exible sliding
footplate. e standard default setting of . m/s was used.
Aer warm-up and familiarization with the movement
pattern, participants were asked to conduct ve concen-
tric repetitions (exion/extension) with maximum voluntary
eort. Participants conducted maximum trials with two-
minute rest in between; the higher value was used for data
analysis. ICC for the maximum leg extension test is . (%
CI: .–.) in our lab.
Maximum isometric strength of the back extensors was
measured using a Schnell Isometric Tester (Schnell, Peuten-
hausen, Germany). Participants were positioned on the dyna-
mometer seat in an upright position and were supported by
thigh and hip straps. e participants had to press backwards
(trunk extension) against the xed lever arm touching the
acromial site (extension). Aer two initial trials of low inten-
sity, participants conducted maximum eorts, each lasting
– seconds, with a -second rest period in between.
Again,thehighervaluewasusedfordataanalysis.Foreach
measurement, the length and axis of the lever arm and the seat
position of the participant were recorded to ensure optimum
repeatability. Reproducibility of the isometric trunk strength
tests (ICC) was . and . for back extension and exion,
respectively.
2.3.3. Confounding Factors. A standardized questionnaire
was applied to determine confounding factors that could
aect the projected outcome parameters. Lifestyle, diseases
and medications, and pain intensity and frequency at dif-
ferent skeletal sites were assessed at baseline and follow-
up. Changes of physical activity and exercise were also
determined by follow-up questionnaires [] and personal
interviews. ICC of the questionnaires were . [] and ..
Individual dietary intake was assessed before and aer trial
Evidence-Based Complementary and Alternative Medicine
by a -day protocol. e consumed food was analyzed using
the Freiburger Ern¨
ahrungsprotokoll (Freiburger Nutrition
Protocol) (Nutri-Science, Hausach, Germany).
2.4. Study Procedure. Participants of the HIT and WB-
EMS exercise group performed weeks of either high-
intensity exercise training or WB-EMS from November
until March and from January until May ,
respectively, in a well-equipped local gym. All the exercise
sessions were consistently supervised; furthermore, partici-
pants recorded intensity, volume, and frequency of exercise
in -week training logs. In both interventions (HIT and WB-
EMS), all participants were requested to maintain their usual
medication, dietary habits, physical activity, and exercise
outside the trial protocol throughout the study course.
2.4.1. Resistance Exercise Training (HIT) Protocol. In this
study, HIT-resistance exercise was dened as single-set-to-
failure protocol with intensifying strategies (manipulations of
rest periods, time under tension, and exercise sequence load
reduction). e exercise protocol scheduled two, rarely three
(th, th, and th week), consistently supervised exercise
sessions per week on nonconsecutive days. All main muscle
groups were addressed by – dedicated exercises/session,
taken from a pool of exercises (latissimus back and
front pulleys, front chin-ups, seated rowing, back extension,
inverse y, hyperextension, sitting bench press, shoulder-
press, military press, buttery with extended arms, crunches,
leg-press, leg extension, leg curls, and leg adduction and
abduction) conducted on resistance devices (Technogym,
Gambettola, Italy). While eight core exercises were applied in
every session, the other exercises were prescribed in only one
of the two or (rarely) three sessions/week.
During HIT period I, two weeks of initial condition-
ing with consistently sets of repetitions (reps.) and
incomplete work to failure (maximum eort - reps.) was
followed by two weeks of single sets with – repetitions
with maximum eort ( rep.). During this rst -week period,
movement velocity (time under tension: TUT) was con-
sistently prescribed as the following: s (concentric), s
(isometric), and s (eccentric).
During the second -week period, the periodized HIT-
training sequence started with the specication to work to
momentary muscular failure (MMF). Prescribing maximum
eort, the number of repetitions decreased linearly over
weeks (th week, – reps., to th week, – reps.), with
each th week planned as a “recreational week” with lower
eort (maximum eort, rep.). In detail, participants were
requested to choose a load so that they could just perform the
prescribed number of repetitions. Sets were always conducted
to MMF, even when participants failed to realize the given
number of repetitions. Rest periods were consistently set at
minutes between exercises. In parallel, movement velocity
varied ranging from TUT “explosive” s, s for the higher
repetition ranges (- reps.) to s, s, and s for the lower
repetition ranges (- reps.).
Additionally, during the third -week period, superset
variations were introduced. Either agonist supersets (“com-
pound sets”) using related muscle groups (i.e., back lat
pulleys, seated rowing, and front chins) or antagonistic
supersets (i.e., leg extension, leg curl, and leg-press) back
to back with minor rest (< s) between the exercises and
minutes between the superset blocks were applied in
alternating sessions. Using this concept, week of this period
was applied as a regeneration week with lower eort.
During the last weeks (period IV) additional drop
sets were introduced. In detail, aer MMF, participants were
requested to reduce the load and exercise again up to MMF.
Single reductions of %–% of the load were prescribed
during the rst two weeks; however, during the last two
weeks, the load reduction of % was followed by another
reduction of –%; thus participants had to work times
to MMF. During the last period movement velocity was
consistently prescribed as (TUT) s, s, and s.
2.4.2. Whole-Body Electromyostimulation (WB-EMS).
BecauseWB-EMStechnologyisarathernoveltechnology,
a brief introduction will be given. Most innovative and
dierent from the well-established local EMS, current WB-
EMS equipment enables the simultaneous activation of up to
– regions or – muscle groups (upper legs, upper arms,
bottom, abdomen, chest, lower back, upper back, latissimus
dorsi, and free options) with dierent selectable intensities.
Adding up the stimulated area, , cm2of body surface
can be activated simultaneously. Strain or more precise
current intensity can be individually selected and modied
during the EMS session. e WB-EMS protocol applied in
the present study scheduled the intermitted low intensity/low
amplitude movement protocol slightly adapted from usual
commercial settings and elaborately described in recent
studies [, , , ]. In detail, participants conducted
a consistently guided and supervised -minute WB-EMS
session times in weeks (i.e., . times per week; each
Monday or Tuesday and each second ursday, Friday, or
Saturday), always on two nonconsecutive days over weeks.
Groups of three participants were coached by a certied
instructor; the session was also acoustically and visually
guided by videos that exactly mimic the s movement and
s rest rhythm of the protocol (see below). Using WB-
EMS devices from miha bodytec® (Gersthofen, Germany),
bipolar electric current was applied with a frequency of
Hzandapulsebreadthof𝜇s intermittently with s
of EMS simulation to perform the movement and s of rest
(Table ). Generally, the WB-EMS protocol closely followed
the typical setting of commercial WB-EMS sessions with their
low loading/low amplitude movement strategy. In summary,
the basic movements (“core exercises”) given in Table
were combined and slightly modied (e.g., twisted crunch)
to generate dynamic exercises that were performed without
any additional weights in a standing position. Exercises were
structured in - sets of – repetitions.
Amplitude, velocity, and corresponding intensity gener-
ated by the movement were set low (i.e., squat: leg-exion:
<∘) to prevent eects from the exercise per se. Additionally,
no progressive increment of intensity with respect to the
exercises was applied during the study phase. Aer a condi-
tioning period of WB-EMS sessions, current intensity was
individually adapted in accordance with the participants in
Evidence-Based Complementary and Alternative Medicine
T : “Core exercises” applied during WB-EMS.
Exercise movements
(1)Squat(sdown)andverticalchestpress/squat(sup)and
vertical rowing
(2) Squat ( s down) and lat pulldown/squat ( s up) with military
press
(3) Deadli ( s down) with arm-curls (ext.)/deadli ( s up) with
arm-curls (ex.)
(4) Squat ( s down), crunch with buttery/squat ( s up) and
reverse y
(5) Squat ( s down) and trunk exion (crunches); return to
upright position
order to generate a rate of perceived exertion (RPE) of “hard”
to “very hard” (Borg CR- Scale “” of “” (impossible)
[]). e corresponding current intensity was saved for
each region on chip cards to generate a fast, reliable, and
valid setting during the subsequent WB-EMS sessions. Aer
this initial setting and a current conditioning period of –
minutes, instructors slightly increased the current intensity
every – minutes in close cooperation with the participants
to maintain the RPE of “hard” to “very hard” during the
session.
2.5. Statistical Analysis. eapriorisamplesizecalculation
referred to lean body mass. Based on a sample size of
subjects per group and a Type Error of %, the statistical
power (1−𝛽) to detect a 10 ± 10% dierence between the
groups was %. Assuming a dropout rate of %, our goal
was to recruit participants per group.
e data were analyzed following a nisher analysis; for
example, all the participants who took part in the follow-up
measurements were included in the analysis irrespective of
theircompliance.Baselineandfollow-updataarereportedas
mean values and standard deviations.
Changes between baseline and follow-up in HIT and WB-
EMS were reported both as absolute (tables) and as per-
centage changes (text). In addition, mean dierences (with
% condence intervals) between HIT and WB-EMS based
on absolute changes were reported in Table . Dierences of
baseline characteristics (Table ) were checked by Welch 𝑡-
test. Where applicable (normal data distribution), analyses of
variance with repeated measurements adjusted for baseline
values were performed to check time ×group interactions;
otherwise, Welch 𝑡-test based on absolute dierences was
used. All tests were -tailed, and statistical signicance was
accepted at 𝑝 < .05. Eect sizes (ES) were calculated using
Cohen’s 𝑑. SPSS . (SPSS Inc., Chicago, IL) was used for all
statistical procedures.
3. Results
During the interventional period of weeks, participants
oftheHITandparticipantsoftheWB-EMSgroupwere
lost to follow-up. As described above, two subjects refused
to join their allocated intervention (HIT) and quit the study
immediately aer randomization. Reasons for withdrawal
were (a) job related relocation (HIT: 𝑛=1; WB-EMS: 𝑛=1),
(b) job related time constraints (HIT: 𝑛=2), and (c) severe
discomfort during the WB-EMS application (𝑛=1).
Relative attendance rate was comparable between the
groups (HIT 93.3 ± 7.0% versus WB-EMS 89.5 ± 10.7%;
𝑝 = .171); net length of training sequence (exercise protocol
only), however, varied signicantly (𝑝 < .001) between the
groups (HIT 30.3 ± 2.3 versus WB-EMS 20 ± 0 minutes).
However, the dierences for total “time under load” between
HIT and WB-EMS (WB-EMS 242 ± 22 versus HIT 365 ±
46min, 𝑝 < .001) did not fully reect the dierence in total
training volume (WB-EMS 403±37 versus HIT 847±87 min,
𝑝 < .001).
As stated, perceived exercise intensity of the WB-EMS
participants was consistently adjusted to an RPE of (
= “hard,” = “very hard”) during the session. In parallel,
the HIT participants’ regular training logs demonstrated a
corresponding RPE of 4.75 ± .28 for the rst -week period,
5.64±4.4 for the second period, 6.42±.39 for the third period,
and 7.31 ±.36 for the last -week period, without considering
the “recreational weeks.”
Duringthestudycourse,norelevantnegativesideeects
with respect to musculoskeletal lesions or diseases related
potentially to the study intervention were recorded.
3.1. Main Outcome Parameters. Ta b l e l i s t s b as e l i n e , f o l l o w -
up, and corresponding changes and group dierences for
LBM and maximum leg-extensor strength. At baseline, bor-
derline signicant dierences were observed for maximum
leg-extensor strength but not for LBM. However, analysis was
consistently adjusted to baseline values.
LBM increased signicantly (𝑝 = .001)inbothgroups
(HIT 1.25 ± 1.44% versus WB-EMS 0.93 ± 1.15%) with no
signicant dierences between the two groups (𝑝 = .395). In
parallel, the signicant changes (𝑝 < .001) of appendicular
skeletal muscle mass (i.e., lean so tissue of the upper and
lower limbs; not given in Table ) in the WB-EMS and HIT
group (0.48± 0.41 versus 0.60±0.45 kg, 𝑝 = .341)conrmed
the results of the LBM assessment.
With respect to changes of regional LBM, we observed
a slight trend to more favorable trunk-LBM changes in the
HIT group (𝑝 = .635), similar changes for the lower limbs
(𝑝 = .968), and % higher upper limb LBM changes in the
HIT group (𝑝 = .039), indicating that LBM changes were not
uniform.
Maximum leg-extensor strength changed favorably in
both groups (HIT 12.7 ± 14.7%, 𝑝 = .002, versus WB-EMS
7.3 ± 10.3%, 𝑝 = .012)withnonsignicant(𝑝 = .215)higher
changes among the HIT group. Isometric back extension
strength increased signicantly (𝑝 < .001)inbothgroups
(HIT 10.2 ± 8.8%versus11.6 ± 10.0%) with no signicant
group dierence (𝑝 = .663).
Total body fat mass decreased signicantly in both groups
(HIT −4.4 ± 7.5%, 𝑝 = .035, versus WB-EMS −3.7 ± 3.9,𝑝=
.001). Dierences with respect to body fat changes adjusted for
baseline total body fat mass were nonsignicant (𝑝 = .829).
us, we have to reject our hypothesis that HIT-resistance
training was signicantly more eective for improving mus-
cle mass and maximum strength than WB-EMS.
Evidence-Based Complementary and Alternative Medicine
T : Baseline and follow-up data, absolute changes, and statistical parameters of primary endpoints in the HIT, WB-EMS, and control
group.
HIT (𝑛=20)
(MV ±SD)
WB-EMS (𝑛=22)
(MV ±SD)
Dierence
MV (% CI) 𝑝Eect size (𝑑)
Lean body mass [kg]a
Baseline . ±. . ±. — . —
weeks . ±. . ±. — ——
Dierence . ±. (.) . ±. (.) . (−. to ) . .
Maximum leg extension strength (leg-press) [N]
Baseline ± ± — . —
weeks ± ± — ——
Dierence ± (.) ± (.) (−. to ) . .
a𝑛=21in the WB-EMS group.
T : Baseline and follow-up data, absolute changes, and statistical parameters of secondary endpoints in the HIT, WB-EMS, and control
group.
HIT (𝑛=20)
(MV ±SD)
WB-EMS (𝑛=22)
(MV ±SD)
Dierence
MV (% CI) 𝑝Eect size (𝑑)
Maximum isometric back extension strength [N]
Baseline . ±. . ±. — . —
weeks . ±. . ±. — ——
Dierence . ±. (<.) . ±. (<.) . (−. to .) . .
Total body fat [kg]a
Baseline . ±. . ±. — . —
weeks . ±. . ±. — ——
Dierence . ±. (.) . ±. (.) . (−. to ) . .
a𝑛=21in the WB-EMS group.
3.2. Secondary Outcome Parameters. Secondary outcome
parameters were given in Table .
3.3. Confounding Parameters. With respect to relevant dis-
eases, participants listed treated hypertension (HIT: 𝑛=2),
reported slight allergic respiratory disorders (HIT: 𝑛=1),
suered from depression (HIT: 𝑛=1),andmenstated
resectionofthethyroidorhypothyroidism(HIT:𝑛=1).
No relevant changes of disease status were reported aer the
interventional period. As per the study criteria, participants
receiving medication aecting the musculoskeletal system
were not included. Further, apart from discontinued hyper-
tension treatment in two participants, no relevant changes of
medication during the study period were reported.
Changes of occupational and leisure time physical activity
(𝑝 ≥ .650) were slight and did not dier between the groups
(𝑝 = .793).Further,averageexerciseparticipationandweekly
exercise volume did not change signicantly in the HIT or
WB-EMS. However, in response to specic inquiries, two
participants (HIT, 𝑛=1, versus WB-EMS, 𝑛=1)admitted
having performed endurance exercise training (running)
with an average volume of and . hours/week in order to
reduce body fat (Table ).
Energy uptake increased nonsignicantly in the HIT
(2.9±9.9%, 𝑝 = .413) and signicantly in the WB-EMS group
(7.8 ± 10.6%, 𝑝 = .010); however, group dierences were
not signicant (𝑝 = .159). In parallel, relative protein intake
(g/kg/d) increased in both groups (HIT 8.3±21.6%, 𝑝 = .349,
versus WB-EMS 11.0 ± 17.5%, 𝑝 = .030)withnosignicant
dierences between the groups (𝑝 = .685). Of importance,
no participants said that they had reduced energy uptake in
order to reduce weight or body fat.
4. Discussion
Time-ecient exercise protocols may be the best choice for
improving tness and body composition of subjects with
limited time resources. In the area of resistance exercise, two
methods, namely, high-intensity training (HIT) and whole-
body electromyostimulation (WB-EMS), were identied as
candidates that satisfy the time-eectiveness requirement. In
respect to body composition, only a few studies determined
the eect of WB-EMS on body fat and/or fat-free mass in
healthy young or middle-aged cohorts [–]. Two of the
three studies that addressed lean body mass reported signi-
cantincreasesoftotalLBM([]:%notgiven,[]:.%)along
with signicant reductions of body fat mass (% and %,
resp.). In contrast, Boeckh-Behrens et al. [–] listed either no
eects[,]orsignicantfatgains[]intheircohortofsports
students albeit with (very) low body fat using a suboptimum
Evidence-Based Complementary and Alternative Medicine
test device. e favorable eect of WB-EMS on muscle mass
parameters (e.g., cross-sectional area (CSA), ber size, and
girth) was conrmed by studies that conducted local EMS
application in healthy nonathletic, nonparalyzed subjects
[–]. While no comparative studies were available for WB-
EMS, the few studies that compared the eect of local EMS
and volitional contraction on muscle mass in healthy nonath-
letic persons determined comparable signicantly positive
(CSA)changesthroughbothmethods[,].However,
although we generally conrmed these results, our approach
was much more pragmatic and focused on comparing two
time-ecient training methods with respect to endpoints
(e.g., body composition) relevant for the potential user.
With respect to strength gains, the signicant positive
eect of WB-EMS in healthy, untrained subjects is undis-
puted [, ]. e maximum isometric and/or dynamic
strength gain of the present study is comparable to data given
for WB-EMS application in studies with trained cohorts (𝑛=
5) [–, , ]. Interestingly, studies that applied local EMS
reported higher average isometric (up to %) or dynamic
maximum (up to %) strength gains with more favorable
results in trained or elite athletes compared with untrained
subjects [].
More relevant for this topic is the question of whether
EMS-induced strength gains were similar to traditional
resistance exercise training in untrained healthy cohorts with
higher training volume. Unfortunately, dierent protocols
for resistance exercise and EMS along with varying end-
points and muscle areas addressed prevent a clear decision.
A simple comparison of EMS applications and resistance
training with respect to strength parameters (i.e., power, max-
imum strength) without considering any further specication
showed either superiority of EMS [], of volitional resistance
exercise training [, ], or no dierence [, , ], at least
in untrained healthy subjects. Hainaut and Duchateau []
conclude aer an early review of the literature that there is
broadagreement“thattheforceincreasesinducedbyEMS
(NMS)aresimilarto,butnotgreaterthan,thoseinducedby
voluntary training.” However, it should be considered that the
levels of evidence generated by these studies conducted in the
eighties are only moderate.
Some study features and limitations may reduce the
impact of our results: () compared with other studies []
focusing on LBM in adults, the study was relatively short (
weeks); further, we did not apply intermitted tests. us, (a)
wecannotexcludethepossibilitythatwedidnotassessthe
main eect of the exercise protocols on LBM and (b) were
unable to evaluate strength kinetics. () We failed slightly
to reach our calculated sample size of participants/group;
however, the dropout rate was lower than expected. Hence,
the power of the study ought to be sucient to detect relevant
eects. () We did not adjust either protocol for exercise
parameters (e.g., exercise volume). Instead, we focused on a
real-world comparison of a novel exercise technology versus a
“gold standard” reference protocol with the common denom-
inator (low) time expenditure. However, with respect to
exercise intensity, we tried to apply comparable prescriptions
of exercise intensity via RPE. () e exercise protocol of
the HIT group was very strenuous; however, due to the low
training frequency and regular regeneration periods, we did
not expect that results were confounded by overreaching
symptoms. () e assessment of exercise intensity by RPE
(Borg CR- Scale) may be critical because this tool has so
far been validated by voluntary exercise. However, we think
it is legitimate to use RPE in this context at least under the
premise that other more objective approaches to identify and
prescribe exercise intensity during WB-EMS and HIT are not
available/applicable. () We focused on untrained middle-
aged men assuming that both WB-EMS and HIT-resistance
exercise training may be equally attractive and feasible for
this cohort and hence this topic may be of high interest with
respect to health promotion. Further, a comparison of EMS
and resistance exercise in trained or athletic cohorts may be
defective due to previous adaption to voluntary exercise in
these cohorts.
5. Conclusion
In summary, we observed comparable or at least similar
increases of muscle parameters aer weeks of WB-EMS
compared with the reference method “HIT.” us, WB-
EMS can be considered as an attractive, time-ecient, and
eective option to HIT-resistance exercise for people seeking
to improve general strength and body composition. On the
other hand, due to the close supervision of present WB-
EMS applications, this exercise technology is much more
expensive. However, taking into account the fact that WB-
EMS technology will become more feasible and cost ecient
over the next few years, the application of WB-EMS will be
increasingly implemented in commercial and noncommer-
cial tness settings.
Conflict of Interests
Noneoftheauthorshadanyadvisoryboardornancial
interests.
Acknowledgments
e authors acknowledge support of the “Benevital” Fitness
Club, Herzogenaurach, Germany, and the Health Sport Club
“Verein Netzwerk Knochengesundheit e.V.,” Erlangen, Ger-
many.
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