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Journal of Sports Research, 2016, 3(2): 44-55
44
† Corresponding author
DOI: 10.18488/journal.90/2016.3.2/90.2.44.55
ISSN(e): 2410-6534/ISSN(p): 2413-8436
© 2016 Pak Publishing Group. All Rights Reserved.
EFFECTS OF HIGH INTENSITY RESISTANCE TRAINING VERSUS WHOLE-BODY
ELECTROMYOSTIMULATION ON CARDIO-METABOLIC RISK FACTORS IN
UNTRAINED MIDDLE AGED MALES. A RANDOMIZED CONTROLLED TRIAL
Wolfgang Kemmler1† --- Matthias Kohl2 --- Simon von Stengel3
1,3Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Henkestrasse Erlangen, Germany
2 Department of Medical and Life Sciences, University of Furtwangen, Neckarstraße Schwenningen, Germany
ABSTRACT
Background: Time-efficient exercise protocols may encourage subjects to exercise more frequently and could thus be
excellent tools for health promotion. The aim of this study was to compare the effectiveness of the time-efficient
methods HIT and/versus WB-EMS on cardio-metabolic risk factors in untrained middle-aged males. Methods:
Untrained, healthy males (30-50 years) were randomly allocated either to 16-weeks of WB-EMS with 3 applications
of 20 min/2 weeks, or 16 weeks of high intensity (resistance) training (HIT) performing 2 sessions/week. Both
methods addressed all the main muscle groups. Metabolic-Syndrome Z-Score (MetS-Z-Score), abdominal body fat
and total cholesterol/HDL-cholesterol (TC/HDL-C) were defined as the study endpoints. Results: HIT and WB-EMS
were similar (p≤.096) effective to improve the MetS-Z-Score (HIT: p=.031 vs. WB-EMS: p=.001) and abdominal
body fat (HIT: -4.5±8.1%, p=.014 vs. WB-EMS -4.0±5.2%, p=.002) in this cohort. No significant changes (HIT: -
2.7±7.4, p=. 216 vs. WB-EMS: -2.2±10.2 p=.441) or group-differences (p=.931) within and between the groups were
determined for TC/HDL-C. Conclusion: WB-EMS and HIT-RT is equally effective, attractive, feasible and time-
efficient methods for combatting cardio-metabolic risk factors in untrained middle-aged males. WB-EMS can be
considered as an effective option, particularly for subjects with low time resources unwilling or unable to conduct
exhausting HIT protocols.
© 2016 Pak Publishing Group. All Rights Reserved.
Keywords: Resistance exercise, Electrical stimulation, Cardio-metabolic risk, Metabolic syndrome, Abdominal fat.
Received: 30 May 2016/ Revised: 9 June 2016/ Accepted: 20 July 2016/ Published: 4 August 2016
Contribution/ Originality
The paper's primary contribution is finding that both exercise methods, high intensity resistance training (HIT) as
defined as “single-set-to-failure protocol with intensifying strategies” and whole-body electromyostimulation (WB-
EMS) are equally effective, attractive and feasible approaches for tackling cardio-metabolic risk factors in untrained
middle-aged males with limited time resources.
1. INTRODUCTION
Time-efficient exercise protocols may be the best choice for promoting the health of subjects with limited time
resources. In the area of resistance exercise (RT), whose general relevance for cardio-metabolic prevention is now
undisputed (Williams et al., 2007; Strasser et al., 2012; Strasser and Pesta, 2013) two methods, namely high intensity
Journal of Sports Research
ISSN(e): 2410-6534/ISSN(p): 2413-8436
URL: www.pakinsight.com
Journal of Sports Research, 2016, 3(2): 44-55
45
© 2016 Pak Publishing Group. All Rights Reserved.
training (HIT) and whole-body electromyostimulation (WB-EMS), were identified as candidates that satisfy the time-
effectiveness requirement. However, the effect of both methods on dedicated cardio-metabolic parameters has yet to
be proved. This is especially the case for WB-EMS, a novel exercise technology that simultaneously innervates up to
12 main muscle groups with dedicated intensity. Although a recent study demonstrated the positive effect of WB-
EMS on body composition in older men with the Metabolic Syndrome (Kemmler et al., 2010) the general effect on
cardio-metabolic indices has not been evaluated yet. Thus, the purpose of this study was to determine the
effectiveness of WB-EMS, compared with a similar time-efficient but more “conventional” resistance exercise
protocol (HIT), concerning cardio-metabolic risk factors in the highly relevant cohort of untrained middle-aged
males.
Our primary hypothesis were that both methods significantly improve the MetS-Z-Score (H1), but the effects of
HIT were significantly more pronounced compared with WB-EMS (H2).
2. MATERIALS AND METHODS
We conducted a 16-week single-blinded, randomized controlled trial, using a parallel group design (Fig. 1). The
study was conducted by the Institute of Medical Physics, University of Erlangen (FAU), Germany. The study was
approved by the ethics committee of the FAU (Ethikantrag 245_13b), and the Federal Bureau of Radiation Protection
(Z5–22462/2–2013-090). All the study participants gave written informed consent prior to study participation.
The study was fully registered under www.clinicaltrials.gov. (NCT02078986). No changes were made to the trial
protocol after commencement. We strictly adhered to the Consolidated Standards of Reporting Trial (CONSORT) for
reporting (randomized) clinical trials (Moher et al., 2010).
2.1. Subjects
Sixty-seven males responded to our personalized letters and were assessed for eligibility (Fig. 1). A total of 57
subjects remained eligible after applying the inclusion criteria of (a) male subjects, 30-50 years old; (b) “untrained
status” defined as no regular resistance exercise training (RT: <1 session/week) and less than 90 min of total
exercise/week; and the exclusion criteria of: (c) pathological changes of the muscle and heart or inflammatory
diseases; (d) medication/diseases affecting muscle metabolism; (e) conditions that prevent WB-EMS (e.g. epilepsy,
cardiac pacemaker), and (f) absence of >2 weeks during the interventional period. Nine subjects withdrew after
informative meetings presenting the specific study design, interventions and measurements (most of these due to
unwillingness to join the randomization procedure (n=5) and/or to conduct the DXA assessment (n=2)). The
remaining 48 subjects were then given the opportunity to draw lots to randomly allocate themselves one of the two
study arms “High Intensity Training (HIT)” and “Whole-Body Elektromyostimulation (WB-EMS)”, with neither the
participants nor the researchers knowing the next allocation. However, since two subjects allocated to the HIT study
arm immediately withdrew after randomization, the randomization sequence was adjusted by replacing a WB-EMS
assignment by a HIT one to generate similar sample sizes per group. Consequently, 23 subjects of the HIT and 23
subjects of the WB-EMS group started the exercise program (Fig. 1). All the study participants were strongly urged to
maintain their physical activity and exercise habits during the study period.
Journal of Sports Research, 2016, 3(2): 44-55
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© 2016 Pak Publishing Group. All Rights Reserved.
Fig-1. Flow diagram through the phases of the present study
Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nürnberg
Table 1 gives baseline characteristics of the subjects. Baseline characteristics and parameters that may have
confounded our results did not vary significantly between the groups.
Tab-1. Baseline characteristics of the HIT and WB-EMS participants; 1 4-day dietary protocol, analyzed by the Freiburger Ernährungs-Protokoll
(Freiburger nutrition protocol, Nutri-Science, Freiburg, Germany); 2 as assessed by chi-square test
Variable
HIT
n=23
WB-EMS
n=23
Difference
(p)
Age [years]
41.9 6.4
43.7 6.1
.429
BMI [kg/m2]
26.9 3.3
28.5 4.1
.151
Total body fat (DXA) [%]
24.7 4.8
26.5 5.2
.220
Exercise volume [min/week]
45.9 37.8
50.2 35.2
.689
Energy Intake [kcal/d]1
2346 463
2387 712
.828
Protein/KH/Fat/Alcohol [% of energy intake] 1
16/46/35/3
17/41/38/4
-----
Overweight (BMI>25 kg/m2) [%]
65
74
.3752
Hypertension (>90 or >140 mmHG) [%]
22
43
.0742
Hypercholesterolemia (>200 mg/dl) [%]
78
78
.6392
Smoker [%]
30
26
.7432
Weekly working time [%]
43.2 3.8
43.2 4.0
.970
Institute of Medical Physics, Friedrich-Alexander University Erlangen Nürnberg
2.2. Procedures
2.2.1. Primary Study Endpoints
Metabolic Syndrome (MetS) Z-Score according to the MetS definition of the International Diabetes
Federation (IDF) (Alberti et al., 2006).
2.2.2 Secondary Study Endpoints
Abdominal body fat (%) as assessed by Dual Energy x-ray Absorptiometry
Rate of Total Cholesterol to High Density Lipid Cholesterol (TC/HDL-C)
Journal of Sports Research, 2016, 3(2): 44-55
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© 2016 Pak Publishing Group. All Rights Reserved.
2.2.3. Explanatory Study Endpoints
Parameters constituting the MetS according to IDF (Alberti et al., 2006).
2.3. Measurements
The subjects were tested at the same time of the day (±1 h) at baseline and follow-up participants within 60 min
by the same researcher. All assessments and analysis were determined in a blinded mode.
2.3.1. Anthropometry
Body height, weight and waist circumference were measured using calibrated devices. Waist circumference was
determined as the minimum circumference between the distal end of the rib cage and the top of the iliac crest along
the midaxillary line.
Body composition was determined by Dual Energy X-ray Absorptiometry (QDR 4500a, discovery upgrade;
Hologic, USA) using the manufacturer's standard protocols. Abdominal body fat was segmented between the lower
end of the 12th thoracic vertebra and the upper end of the iliac crest. Follow-up segmentation was conducted using
the “compare mode”, which retained the area of the initial segmentation.
2.3.2. Blood Parameters
After an overnight fast, blood was sampled in the morning (7:00 to 9:00) in a sitting position from an antecubital
vein. Serum samples were centrifuged at 3000 RPM for 20 minutes and analyzed by the “Zentrallabor” of the
Medical Department, University of Erlangen-Nürnberg. Glucose, total cholesterol, HDL- and LDL cholesterol and
triglycerides (Olympus Diagnostica GmbH, Hamburg, Germany) were determined.
Blood pressure was determined in a sitting position after 5 minutes' rest with an automatic oscillometric device
(Bosco, Bosch, Jungingen, Germany). All measurements were taken in a non-fasting condition. Subjects were asked
to avoid relevant physical activity 12 hours before the tests and to refrain from coffee or tea for at least two hours
prior to testing.
2.3.3. Metabolic Syndrome
The MetS-Z-Score was calculated according to the calculation proposed by Johnson et al. (2007) albeit based on
the more recent MetS definition presented by the IDF (Alberti et al., 2006) instead of the NCEP-ATP-III definition
(Expert-Panel, 2001). Under the IDF definition, MetS is prevalent if waist circumference is increased (≥94 cm for
Caucasian males) and two of the four following factors are also present: (1) raised triglyceride (TriGly) levels ( 150
mg/dl (2) reduced HDL-C (<40 mg/dl for males; or specific treatment for previously detected hypertriglyceridaemia /
reduced HDL-C) (3) raised blood pressure (85 or 135 mmHG, or specific treatment) (4) raised fasting plasma
glucose ( 100 mg/dl, or previously diagnosed type 2 diabetes). Based on these cut-off points, the individual data and
the corresponding baseline standard deviation (SD) of the entire cohort the Z-Score was calculated as follows: [(40 –
HDL-C)/ SD HDL-C] + [(TriGly - 180)/ SD TriGly] + [(Glucose - 100)/ SD Glucose] + [(waist circumference (WC)
- 94)/ SD WC] + [(Mean arterial (blood) pressure (MAP) – 107.5)/ SD MAP].
2.3.4. Baseline Characteristics, Confounding Factors
Lifestyle, diseases and medication, pain intensity and frequency at different sites were assessed at baseline and
follow-up by standardized questionnaires. Changes in physical activity and exercise were also determined by follow-
up questionnaires (Kemmler et al., 2004) and personal interviews.
Dietary intake of the participants was assessed pre- and post-trial by a 4-day dietary protocol. The consumed
food was analyzed using the Freiburger Ernährungs-Protokoll [Freiburger Nutrition Protocol] (nutri-science,
Hausach, Germany).
Journal of Sports Research, 2016, 3(2): 44-55
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© 2016 Pak Publishing Group. All Rights Reserved.
2.4. Study Procedure
Participants of both groups conducted a 16-week HIT or WB-EMS intervention from November 2014 until
March 2015 or from January 2015 until May 2015 in a local gym (Benefital, Herzogenaurach, Germany). All the
exercise sessions were supervised; further individual 4-week training logs, prescribing intensity, volume and
frequency of the exercise given to the participants were regularly checked and recorded by research assistants.
Participants were urged not to vary their medication, dietary habits, physical activity and exercise throughout the
study course.
2.4.1. Hit Protocol
HIT-resistance exercise was defined as “single-set-to-failure protocol with intensifying strategies”. The exercise
protocol scheduled two, rarely three (9th, 13th, 16th week) exercise sessions per week on non-consecutive days. All the
main muscle groups were addressed by 10-13 exercises/session taken from a pool of 17 exercises conducted on RT
devices (Technogym Gambettola, Italy). Tab. 2 gives the composition of the HIT protocol.
After 4 weeks of conditioning the periodized 12-week HIT-training sequence started with the specification to
work to momentary muscular failure (MMF). Following a maximum effort approach (MMF), the number of
repetitions was decreased linearly over 3 weeks with each 4th week planned as a “recreational week” with lower effort
(maximum effort – 1 rep). In detail, participants were requested to choose a load such that they were just able to
perform the prescribed repetitions. Sets were always conducted to MMF, even when subjects failed to achieve the
given number of repetitions. Superset variations conducted either as agonist supersets using related muscle groups
(i.e. back lat pulleys, seated rowing, front chins) as or antagonistic supersets (i.e. leg extension, leg curl, leg press)
were introduced during the third 4-week phase. Lastly, and additionally, during the last 4-week phase, “drop sets”
were prescribed. Under this concept, after “initial” MMF, subjects were requested to reduce the load once (week 13,
14) or twice (week 15, 16) and work again up to MMF (Tab. 2).
Tab-2. Details of the HIT exercise protocol.
Time
Number of Reps (Break)
Work to failure strategy
TUT (s)
Phase 1:
1-2 week
3-4 week
conditioning phase:
2 x 15 Reps (break: 90 s)
1 x 8-10 Reps (break 90 s)
MMF – 2-3 Reps
MMF – 1 Rep
2 - 1- 2
Phase 2:
5-8 week
8-10 Reps (break 2 min)
5-7 Reps (break 2 min)
3-5 Reps (break 2 min)
RegW: 10-12 Reps (break 2
min)
MMF
MMF
MMF
MMF – 1-2 Reps
expl - 1 - 2
expl - 1 - 2
3 – 1 - 4
2 – 1 - 2
Phase 3:
9-12 week
see phase 2, however, break
between SuS-exercises: <20 s;
between SuS-“blocks“: 2 min
week 4: RegW (s. Phase 2)
see phase 2 + Supersets:
1. session/w. agonists SuS1
2. session/w antagonists SuS2
2-4 exercises per SuS-„block“
see
phase 2
Phase 4:
13-16
week
see phase 3
see phase 3 and one or two Drop-sets:
week 13, 14: 1 Drop-set (-10 to 25% load)
week 15, 16: 2 Drop-sets (-10-20% und -20% load)
2 – 1 – 2
to
3 – 1 - 3
Reps: repetitions, TUT: Time under Tension (s concentric - s isometric – s excentric range), MMF: work to momentary muscular failure; RegW: regeneration week;
expl: explosive movement; SuS: supersets; DropSets: immediate exercise with slightly reduced weight. 1subsequent training of identical muscle groups; 2 intermitted
training for agonist/antagonist.
2.4.2. Whole Body Electromyostimulation (WB-EMS)
In contrast to the classical local application, the WB-EMS technology vests and cuffs electrodes (Miha bodytec,
Gersthofen, Germany) used in our studies allow simultaneous but dedicated control and innervation of 8-10 muscle
groups with a total electrode area of up to 2800 cm2.
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© 2016 Pak Publishing Group. All Rights Reserved.
We applied a WB-EMS protocol involving a bipolar impulse. Based on the available literature (Lam and Qin,
2008; Filipovic et al., 2011) and our past experience (Kemmler et al., 2010; Kemmler et al., 2010; Kemmler et al.,
2011; Kemmler et al., 2014) the stimulation frequency was selected at 85 Hz, the impulse width at 350 microseconds
and the impulse rise as direct (rectangular application). Impulse duration was 6 sec with a 4-sec break between the
impulses. Groups of three participants guided by a certified instructor conducted 20 min WB-EMS-sessions 3 times
in 2 weeks (each Monday or Tuesday and each second Thursday or Friday or Saturday), always on two non-
consecutive days. In order to generate an effect throughout the range of motion, slight movements were performed in
a standing position during the impulse phase as per the instructions in videos that exactly mimic the 6 s movement
and 4 s rest rhythm of the WB-EMS protocol.
To generate an adequate intensity of the WB-EMS application, subjects were requested to exercise at a rate of
perceived exertion (RPE) of between “somewhat hard” and “hard” (Borg CR-10 Scale “6” of “10” (impossible) (Borg
and Kaijser, 2006). Initially, the impulse intensity was individually adapted in close cooperation with the participant.
The corresponding impulse intensity per muscle group was saved on smart cards to ensure a fast, reliable and valid
application during the subsequent WB-EMS sessions. Then this setting was successively increased every 3-5 min
during the WB-EMS session to achieve the objective of RPE “hard” to “very hard”.
2.5. Statistical Analysis
We calculated an a priori sample size estimation that focused on “Lean Body Mass”. Based on a Type 1 Error of
5% and a statistical power (1-β) of 90% a sample size of 21 subjects per group was sufficient to detect a 10% (SD:
10%) LBM difference between the groups. Anticipating a dropout rate of ≈15-20%, we aimed to recruit ≈25 subjects
per group.
An Intention to Treat (ITT) analysis was conducted that included all participants with baseline data. The ITT
analysis was performed using the statistics software R (R Development Core Team Vienna, Austria) in combination
with multiple imputation by Amelia II. The full data set was used for multiple imputation, with imputation being
repeated 50 times. In addition, the approach of Barnard and Rubin (1999) was used to compute mean, SD
(combination of within- and between-imputation variance) and p values (t-distribution with adjusted degrees of
freedom). In all cases, the results obtained were in very good agreement with the respective results determined with
the approach of Steele et al. (2010).
Baseline and follow-up data were reported as mean values (MV) and standard deviations (SD). Changes between
baseline and follow-up within the HIT and WB-EMS group were described as absolute (tables) and percentage
changes (text). With respect to the comparison of the groups, mean differences (with 95% confidence intervals)
between HIT and WB-EMS based on absolute changes were reported in the tables. Welch T-Tests were consistently
applied to check for differences between the groups (Ruxton, 2006). All tests were 2-tailed, statistical significance
was accepted at p<.05. Effect sizes (ES) were calculated using Cohen´s d´. SPSS 21.0 (SPSS Inc, Chicago, IL) was
used for all statistical procedures apart from multiple imputation.
3. RESULTS
Baseline characteristics did not vary significantly between the groups (Tab 1). The majority of participants were
overweight or demonstrated central obesity (HIT: 70% vs. WB-EMS: 78%) according to IDF (Alberti et al., 2006).
With respect to relevant diseases, 4 subjects listed (treated) Diabetes Mellitus Type-II (HIT: n=1), 5 subjects reported
slight allergic respiratory disorders (HIT: n=1), 2 participants suffer from depression (HIT: n=1), 3 males indicate
resection of the thyroid or hypothyroidism (HIT: n=1). Energy and macro-nutritional intake per se was inconspicuous
and did not vary between groups. All participants were in full-time employment, 78% of the participants of both
groups were white-collar workers in middle to upper positions.
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© 2016 Pak Publishing Group. All Rights Reserved.
Three participants of the HIT and two participant of the WB-EMS group were lost to follow-up. Further, as
already mentioned, two subjects refused to join their allocated intervention (HIT) and quit the study immediately after
randomization without any assessments. One subject gave the study intervention as the reason for withdrawing
(“severe discomfort during the WB-EMS application”), four others stated job-related relocation (HIT: n=1, WB-
EMS: n=1), or job-related time constraints (HIT: n=2) (Fig. 1).
The attendance rate of both methods was high (HIT: 93.3±7.0% vs. WB-EMS: 89.5±10.7%) and did not vary
relevantly between the groups (p=.171). With respect to time efficiency, the length of the HIT sequence averaged
30.3±2.3 min/session; the corresponding duration of WB-EMS was 20±0 min. However, taking into account that HIT
participants exercised at least twice per week, while WB-EMS participants exercised on average 1.5 times per week,
the total volume of exercise conducted in the HIT group was twice (p<.001) as high (847±87 min) compared with the
WB-EMS group (403±87 min).
As described above, the perceived exercise intensity of the WB-EMS participants was consistently adjusted to
maintain an RPE of at least 6 (5=“hard”, 7=“very hard”) during the session. Due to the progression of the HIT
protocol (Tab. 2) participants reported an almost linear increase in their RPE starting with 4.75±.28 for the first 4-
week period, 5.64±4.4 for the second, 6.42±.39 for the third and finally 7.31±.36 for the last 4-week period.
No relevant negative side effects with respect to musculoskeletal lesions or diseases potentially related to the
study intervention were recorded during the study period.
3.1. Study Endpoints
Table 3 lists baseline and follow-up data, corresponding changes and group differences for MetS-Z-Score,
abdominal body fat rate and the proportion of total cholesterol to HDL-C. At baseline, no relevant group differences
were observed for the given parameters. MetS-Z-Score significantly improved in both groups (p≤.031) with no
significant differences between the two groups (p=.096). Thus, we verify our hypothesis H1 “that both methods
significantly improve the MetS-Z-Score”, but reject H2 “that the effects of HIT was significantly more pronounced
compared with WB-EMS”.
Percent body fat rate decreased by -4.5±8.1% (p=.014) in the HIT and 4.0±5.2% (p=.002) in the WB-EMS with
no significant difference between the groups (p=.895). No significant changes (HIT: -2.7±7.4, p=. 216 vs. WB-EMS:
-2.2±10.2 p=.441)
1
and no significant differences (p=.931) within and between the groups were determined for the
rate of total cholesterol to HDL-cholesterol (Tab. 3).
Tab-3. Changes of primary study and secondary endpoints[6] in the HIT and WB-EMS group. ITT-analysis
HIT (n=23)
WB-EMS (n=23)
Absolute difference
MV (95% CI)
p
(d)
MetS-Z-Score [Index]1
Baseline
-0.74 ± 3.46
0.23 ± 3.19
-----
.274
-----
Difference
-0.52 ± 1.12 (p=.031)
-1.16 ± 1.43 (p<.001)
.63 (-.11 bis 1.38)
.096
.50
Abdominal body fat [%]
Baseline
27.65 ± 6.52
29.30 ± 6.10
-----
.395
-----
Difference
-1.24 ± 2.27 (p=.014)
-1.17 ± 1.53 (p=.002)
0.07 (-1.06 bis 1.20)
.895
.04
Total Cholesterol /HDL-Cholesterol [rate]2
Baseline
4.52 ± 1.03
4.53 ±.089
-----
.968
-----
Difference
-0.12 ± 0.46 (p=.216)
-0.10 ± 0.63 (p=.441)
0.02 (0.32 to 0.35)
.931
.04
1 negative Z-Score values were favorable, further a negative change of the MetS-Z-Score can be considered as an improvement.
1
Negative changes of the TC/HDL-C rate can be considered as an improvement.
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Table 4 show baseline and follow-up data, corresponding changes and group differences for parameters (except
HDL-C) constituting the MetS according to IDF (Alberti et al., 2006).
Tab-4. Changes of selected parameters constituting the Metabolic Syndrome in the HIT and WB-EMS group. ITT-analysis.
HIT (n=20)
WB-EMS (n=21)
Absolute Difference
MV (95% CI)
p
(d)
Waist circumference [cm]
Baseline
100.5 ± 9.6
102.6 ± 9.4
-----
.480
-----
Difference
-2.10±4.13 (p=.021)
-3.41±4.52 (p=.002)
1.31 (-1.25 bis 3.87)
.306
.30
Mean Arterial Blood Pressure [mmHG]
Baseline
106.4 ± 9.6
110.8 ± 10.0
-----
.158
-----
Difference
-3.64 ± 5.63 (p=.005)
-4.86 ± 7.33 (p=.005)
1.22 (-2.69 bis 5.13)
.529
.19
Glucose [mg/dl]
Baseline
94.3 ± 18.5
95.3 ± 14.6
-----
.837
-----
Difference
1.74 ± 8.53 (p=.320)
-4.27 ± 8.98 (p=.035)
6.01 (0.79 bis 11.24)
.025
.69
Triglycerides [mg/dl]
Baseline
139.5 ± 61.0
161.2 ± 93.8
-----
.383
-----
Difference
-10.1 ± 47.9 (p=.307)
9.5 ± 55.5 (p=.423)
19.5 (-10.8 bis 49.9)
.200
.38
3.2. Confounding Parameters
In summary, no relevant changes of occupational, disease, or medication status was reported after the
interventional period. Self-reported occupational and leisure time physical activity increased slightly and comparably
(p=.793) in both groups (3-6%; p≥.650). Similarly, average exercise participation and weekly exercise volume did not
change significantly in the HIT or WB-EMS. However, in response to a specific query two participants (HIT: n=1 vs.
WB-EMS: n=1) with particular high weight loss admitted they had started endurance exercise training (2 and 2.5
h/week running) after the second and fourth week of the study intervention.
Dietary intake parameters changed considerably in both groups, but none of the subjects said they had changed
their nutritional intake in order to reduce weight or body fat. Energy uptake comparably (p=.159) increased in both
groups (HIT: 2.9±9.9%, p=.413 vs. WB-EMS 7.8±10.6%, p=.010). In parallel, relative protein-intake (g/kg/d)
increased in the HIT (8.3±21.6%, p=.349) and WB-EMS group (11.0±17.5%, p=.030) similarly (p=.685), resulting in
a protein uptake of 1.10±0.22 (HIT) and 1.20±0.27 g/kg body-weight (WB-EMS group) respectively (p=.247).
4. DISCUSSION
The primary finding of the study was that both interventions, HIT (“single-set-to-failure”) and WB-EMS were
equally effective for significantly improving the MetS-Z-Score and abdominal body fat in untrained middle-aged
males. However only slight, non-significant positive effects were determined for total Cholesterol/HDL-C rate, a
parameter still considered as one of the most meaningful predictors of future cardiovascular events (Ridker et al.,
2005). Based on our previous findings (Kemmler et al., 2010; Kemmler et al., 2014) we hypothesized that HIT
exercise was significantly more effective for combatting cardio-metabolic risk factors compared with WB-EMS,
which was obviously not the case. With respect to time-effectiveness and feasibility both training methods were
attractive, which was demonstrated by net exercise times around 30 min or less (WB-EMS), low dropout (Pahmeier,
1994) and high attendance rates (Peterson et al., 2010). With one slight exception, we did not detect any changes in
confounding parameters that may have limited the evidence of our finding. Most important, physical activity, diseases
and medical treatment remained stable during the study period. Although energy intake rose by 3% (HIT) and 8%
(WB-EMS) with a largely parallel development of macro-nutritional intake, these factors should not contribute to the
improvement of central obesity or MetS-Z-Score. Thus, we conclude that HIT and WB-EMS were comparably
effective and feasible methods to favorably address cardio-metabolic risk factors in untrained middle-aged males.
This finding was not supported by a recent study of Bateman et al. (2011) which did not report any positive RT-
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induced changes of the MetS-Z-Score (ATP-III definition (Expert-Panel, 2001) or its components in overweight
dyslipidemic subjects 18-70 years old. However, apart from the chosen cohort, the progressive RT protocol of the
authors considerably vary from the present HIT-program with respect to relative intensity, (no requirement to train to
MMF), duration (8 months), volume (3 days/week, 3 sets/exercise, 11 exercises/session) and variation / periodization
(consistently 8-12 reps/session over 8 months).
Looking behind the covariates of the MetS, MAP and waist circumference demonstrated the most pronounced
reductions, with the latter result confirming our finding of significantly reduced abdominal fat as determined by
DXA. While the positive effect of RT on blood pressure is generally accepted (Kelley and Kelley, 2000; Cornelissen
and Fagard, 2005; Cornelissen and Smart, 2013) most researchers apply moderate intensity resistance exercise
protocols. However, a recent meta analysis demonstrated similar effects of low, moderate or high (≥70% 1RM)
intensity exercise programs on systolic and diastolic blood pressure (Cornelissen and Smart, 2013). Although there is
some evidence that RT positively effects visceral obesity (Strasser et al., 2012) it could not necessarily be expected
that both programs reduce abdominal body fat, at least considering the low exercise volume and short duration of the
intervention. Using indirect calorimetry we recently determined a rather low total energy expenditure (EE) of
(140±19 kcal) for a comparable 20 min WB-EMS protocol (Kemmler et al., 2012). However, the high muscular
tension of HIT-RT and particularly WB-EMS with its preferential activation of glycolytic type II fibers (Bossert et
al., 2006) required fast extra-mitochondrial energy production that prevents the valid assessment of EE by real-time
methods such as indirect calorimetry(LaForgia et al., 2006; Robergs et al., 2007; Scott et al., 2009). Robergs et al.
(2007) used multiple regression analysis to predict the (real) metabolic costs of RT above steady state conditions
(Scott et al., 2009) (i.e. 65 and 70% 1RM; compared with ≥75% 1RM in the present study) and calculated EEs 2-3
times higher (15.3 and 16.3 kcal/min-1) than determined by indirect calorimetry. Additionally excessive post-exercise
energy consumption (EPOC) is primarily related to exercise intensity (LaForgia et al., 2006) thus the pronounced
loading during HIT-RT and WB-EMS should result in very distinct raises of EPOC and correspondingly high post-
exercise EE. Finally the significant raise of muscle mass generated by both programs (Lean Body Mass HIT:
1.251.44%, WB-EMS: 0.931.15%) (Kemmler et al., 2015) also contribute to an increased EE (Stiegler and
Cunliffe, 2006; Strasser et al., 2012) although the relevance of this mechanism may be limited due to the short study
duration. With one exception, (resting glucose in the WB-EMS group) blood parameters did not show significant
favorable effects after the HIT- or WB-EMS intervention. With respect to HIT-RT, a largely identical 20-week
“single set to failure protocol” (Kemmler et al., 2014) in general created positive effects on HDL-C, LDL-C and
triglycerides, although significance was reached for triglycerides only. On the other hand, a recent study with elderly
males with MetS confirmed our finding of missing positive effects on lipids and lipoproteins after 20 min of WB-
EMS application (Kemmler et al., 2010).
In order to properly gauge the relevance, evidence and generalizability of our results, some particular features
and limitations of the study must be addressed. (1) Our choice to use the MetS-Z-Score as the primary study endpoint
offers strengths and limitations. Most critically, only a few exercise studies addressed this endpoint, thus preventing a
sophisticated discussion of our study results. Compared with other cardio-metabolic indices (i.e. 10-year CHD risk-
score (Wilson et al., 1998) PROCAM (Assmann et al., 2002) the MetS-Z-Score exclusively focused on modifiable
risk factors and was thus more eligible for our interventional research question. (2) Furthermore, some statistical
limitations may reduce the evidence generated by the study. Firstly, drawing lots may not be the most sophisticated
randomization strategy. However, in the past (Kemmler et al., 2011; Kemmler et al., 2014) our approach of
transferring the randomization process to the participants led to high participant adherence. This time, however, two
subjects immediately quit the study after “they had allocated themselves” to the obviously undesired study arm,
although initially all the subjects agreed to accept the decision by lots. Consequently, we slightly failed to reach our
calculated sample size of ≈25 subjects/group; however due to the lower than expected dropout rate, the statistical
power of the study ought to be sufficient to detect relevant effects. Finally, related to a lack of corresponding
Journal of Sports Research, 2016, 3(2): 44-55
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literature, we are unable to generate a directional hypothesis, which was also a minor methodological limitation of the
study. (3) We focused on a homogeneous cohort of untrained middle-aged males assuming that both WB-EMS and
HIT-RT may be equally attractive and feasible for this cohort. We feel that the results would transferable to
corresponding female cohorts, however from a pragmatic point of view a comparison of HIT and WB-EMS in female
cohorts was of lesser relevance due to the muted enthusiasm for MMF-HIT-RF protocols in female cohorts.
Nonetheless, the relevance of WB-EMS application may be particularly high for female cohorts.
5. CONCLUSION
In summary, WB-EMS and HIT-RT are equally attractive, feasible and time-efficient methods for tackling
cardio-metabolic risk factors in untrained middle-aged males. Since this finding can be applied to muscle mass and
strength (Kemmler et al., 2015) WB-EMS can be considered as an effective but pricey option particularly for subjects
with low time resources and who unwilling or unable to conduct exhausting HIT protocols.
Funding: This study received no specific financial support.
Competing Interests: The authors declare that they have no competing interests.
Contributors/Acknowledgement: All authors contributed equally to the conception and design of the study. We would
like to thank “Benevital Fitness Club”, Herzogenaurach, Germany, and the health sport club “Verein Netzwerk
Knochengesundheit e.V.”, Erlangen, Germany for their support. We further acknowledge the help of Marc Teschler
and Dr. Michael Bebenek (IMP, FAU, Erlangen, Germany) that supervised the intervention.
Competing Interests
None of the authors has any conflict of interest. Further, the study was conducted without any external funding.
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