Fig. 11.1
WB-EMS equipment (Miha bodytec, Gersthofen, Germany)
From the multitude of possible compositions of the current parameters (impulse type, frequency, duration, width, and rise), we applied a similar protocol in all studies that was based on bipolar pulse mode. Based on the available literature, the stimulation frequency was selected at 85 Hz [12, 13], the impulse width at 350 μs [12], and the impulse rise as direct (rectangular application) [14]. Impulse duration ranged between 4 and 6 s with a 4-s break between the impulses. However, in two trials (TEST I and II), an adjuvant continuous 7 Hz-WB-EMS program was applied. Total exercise duration of a session (with breaks) was 18–25 min, taking into account the setup time for WB-EMS a typical session lasted not more than 30 min. Of importance, the equipment used allows a dedicated intensity of the current per muscle group addressed (Fig. 11.2).
Fig. 11.2
WB-EMS operator device (Miha bodytec, Gersthofen, Germany)
Unfortunately, we are unable to prescribe the exact stimulation intensity (in mA) due to regional and individual disparities of current sensitivity. Thus, to achieve an adequate intensity of the EMS application, participants were requested to exercise at a rate of perceived exertion (RPE) between “somewhat hard” and “hard” (see below) (Table 11.1).
Table 11.1
Exercises performed during WB-EMS (examples)
Exercise | Primary loaded region |
|---|---|
1. Squat, arm flexion, and extension | Leg extensors, flexors, buttocks, arm flexors, extension |
2. Squat and crunch | Leg extensors, flexors, buttocks, abdomen |
3. Squat, latissimus pulleys (down) und shoulder press (up) | Leg extensors, flexors, buttocks, arm flexor, arm extensor, shoulder, chest, upper back |
4. Squat, butterfly (down) und reverse fly (up) | Leg extensors, flexors, buttocks, chest, upper back |
5. Lunges, chest press, and vertical rowing | Leg extensors, flexors, buttocks chest, upper back |
Exercises were carried out in a dynamic mode without additional weights
The number of repetitions per exercise varied between 6 and 8 repetitions per set, with 1–2 sets/exercise being performed. As mentioned above, based on our intensity requirements, the EMS application should be perceived as “strenuous (hard) to very strenuous (very hard)” (RPE 5–7 on the 10-step (cr10) Borg Scale [15]).
Measurements and Test Procedures
The status of each participant (WB-EMS or control group) was not apparent for the investigators; corresponding questioning was not allowed. Measurements at study start and for follow-up were always performed and evaluated by the same researcher at the same time of day (±2 h).
Statistical Procedures
In all studies, a formal sample size analysis appropriate for the primary study endpoint was calculated. The intention-to-treat (ITT) principle, the completer analysis, and the per-protocol method were used to analyze the data of the trials. Baseline values are reported as means and standard deviations. Within-group changes between baseline and follow-up were reported as relative changes (text) or absolute changes (tables). Depending on the data distribution, analysis of variance with repeated measures, t-tests, and corresponding parameter-free methods were used. The distribution of data was always tested graphically and statistically. A significance level of p < 0.05 is considered significant. Effect sizes were calculated using Cohen’s d [16]. SPSS versions 16.0–21.0 (SPSS Inc., Chicago, IL, USA) were used for all statistical procedures except for the ITT analysis and the multiple imputation performed in TEST V.
Study 1
Training Und Electromyostimulation Trial I (TEST I) [8]
Motivation and Study Aim
The aim of this pilot study was to detect the effect of WB-EMS training on body composition, physiological and functional parameters, as well as on feasibility and participant acceptance in older women with considerable exercise training experience. Our hypothesis was that an adjuvant WB-EMS training significantly increases the effects of conventional multifunctional exercise training [17] on (a) muscle mass, (b) fat mass, and (c) muscle strength.
Methodology
The TEST I (Training and Electromyostimulation) study is a randomized, controlled, single-blinded intervention study over 14 weeks. The study was conducted from February to August 2008 at the Institute of Medical Physics.
Study Endpoints
Lean body mass (LBM)
Body fat mass
Maximum isometric trunk (back) and leg extensor strength
Participants
Thirty women 60 years and older (64.5 ± 5.5 years) from the Erlangen-Nuremberg region with more than 3 years’ training experience in conventional resistance exercise training were randomly assigned to a WB-EMS exercise group (n = 15) or a non-EMS-exercising control group (n = 15). Both groups maintained their conventional exercise training, however.
Exclusion criteria were epilepsy, cardiac pacemaker, serious circulatory disorders, abdomen/groin hernia, tuberculosis, cancer, serious neurological disturbances, inflammatory diseases, bleeding tendencies, medication or diseases affecting muscle metabolism, inflammatory diseases, tuberculosis, tumor, severe neurological disorders, and large-scale skin injuries in the area of the electrodes. Table 11.2 shows the initial characteristics of the groups.
Table 11.2
Baseline characteristics of the TEST I study groups
Variable | WB-EMS (n = 15) | CG (n = 15) |
|---|---|---|
Age [years] | 65.6 ± 5.6 | 63.3 ± 5.4 |
BMI [kg/m2] | 26.1 ± 4.4 | 24.7 ± 2.6 |
Lean body mass (LBM) [kg]a | 40.7 ± 4.1 | 41.1 ± 3.4 |
Energy intake [kJ/day]b | 7689 ± 1722 | 7824 ± 1640 |
Vitamin-D intake [μg/day]b | 6.4 ± 2.1 | 7.1 ± 2.4 |
Exercise volume [min/week] | 179 ± 58 | 147 ± 43 |
Intervention
While the control group (CG) maintained their intense physical training (two sessions of 60 min; two home-training sessions of 20 min) described in detail elsewhere [17, 19], the treatment group (WB-EMS) additionally performed a 14-week EMS program with EMS application every 4–5 days (three training sessions in 2 weeks) with the strain parameters given above.
Measurements
Anthropometry
Body height, weight, and circumference values of the subjects were measured using calibrated devices. The muscle mass was indirectly measured via resting metabolic rate (RMR) as assessed by spirometry [20, 21]. The RMR was measured after 12 h of fasting and with 24-h abstinence of heavy physical activity between 7:00 and 9:00 during the last 15 min of a 30-min rest lying in a supine position. The measurement was carried out using mobile spirometry (Viasis, Conshohocken, USA).
For the determination of body fat and fat-free mass, the skinfold thickness at different body areas was measured using a calibrated caliper (Lange, Cambridge, USA). Tests were performed twice, and the mean value of both tests was included in the analysis. Based on these data, body composition parameters were calculated using the 7-point skinfold method suggested by Durnin-Womersley [18].
The maximum isometric strength of the trunk and leg extensors was evaluated by a “Schnell m3-tester” (Schnell, Peutenhausen, Germany) as per the test protocol of Tusker [22].
A detailed questionnaire was used to assess well-being, pain frequency, and intensity at different skeletal sites, prestudy exercise levels, normal daily activity levels, diseases, and medication. The follow-up questionnaires also contained sections to monitor disease incidence, changes in disease severity and intake of medication, lifestyle changes, or sport activities outside the TEST training program.
Statistical Procedures
The formal sample size analysis of the TEST I study was based on the parameter “resting metabolic rate” (RMR). An intention-to-treat (ITT) analysis was performed, in which all the participants were included with baseline data.
Results
All the participants were able to complete the training according to the protocol. The attendance rate for the conventional training protocol was comparable between the groups and ranged at 81%. The corresponding rate for the WB-EMS training attendance was 98%. The mean overall intensity of the EMS application over the intervention period was rated by the participants as “hard” to “very hard” (6.0 ± 0.5 on the cr10 Borg Scale [15]).
During the intervention period, no adverse events or changes occurred that may affect our results.
Table 11.3 listed the results of the ITT analysis for the study endpoints.
Table 11.3
Baseline values, intragroup changes, and intergroup differences for resting metabolic rate (RMR) and lean body mass and strength
WB-EMS (n = 15) ( (MV ± SD) | CG (n = 15) (MV ± SD) | Difference MV (95% CI) | p | ES | |
|---|---|---|---|---|---|
Resting metabolic rate RMR (kcal/h) | |||||
Baseline | 61.6 ± 10.6 | 60.0 ± 9.7 | – | – | – |
Difference (p) | −0.1 ± 4.8 (.991) | −3.2 ± 5.2 (0.038) | −3.2 (−7.0–0.6) | 0.095 | 0.62 |
Lean body mass [kg] a | |||||
Baseline | 41.78 ± 4.58 | 43.60 ± 4.80 | – | – | – |
Difference (p) | 0.17 ± 0.75 (.388) | −0.40 ± 0.78 (.060) | 0.56 (0.11–1.11) | 0.046 | 0.75 |
Body fat mass [%] a | |||||
Baseline | 34.78 ± 5.40 | 33.62 ± 7.47 | – | – | – |
Difference (p) | −1.12 ± 1.8 (0.031) | −0.01 ± 1.50 (0.974) | 1.10 (−0.13–2.33) | 0.077 | 0.67 |
Isometric maximum strength trunk extensors [N] | |||||
Baseline | 116.3 ± 33.8 | 119.5 ± 40.0 | – | – | – |
Difference (p) | 11.5 ± 12.8 (0.015) | −7.6 ± 12.2 (0.054) | −19.2 (−32.4–6.0) | 0.006 | 1.53 |
Isometric maximum strength leg extensors [N] | |||||
Baseline | 827 ± 209 | 889 ± 191 | – | – | – |
Difference (p) | 80 ± 77 (0.001) | −40 ± 90 (0.106) | −121 (−184–57) | 0.001 | 1.43 |
In summary, our hypotheses (a–c) cannot be fully confirmed. Based on (a) muscle mass, the two assessment methods showed slightly different results. Only the caliper tests [18] resulted in a marginally significant difference between WB-EMS and the control group which maintained its conventional exercise training (CG). Although our results showed a strong tendency for more favorable changes of body fat mass in the WB-EMS group, our hypothesis (b) cannot be verified, while for (c) muscle strength, our hypothesis can be fully confirmed.
Summary and Conclusion of the TEST I Study
The aim of the present study was the general evaluation of the effectiveness, feasibility, and acceptability of WB-EMS in elderly women with considerable experience in (resistance) training and correspondingly pronounced perceived exertion appraisal. The study design prescribed an adjuvant WB-EMS application in parallel to an intense, conventional multipurpose exercise training protocol focusing on muscle strength. Particularly noteworthy appears that the adjuvant WB-EMS training generated (significant) positive effects on muscle and body fat even in this powerful cohort of elderly females with high baseline fitness levels. Moreover, muscle strength was also significantly improved by the WB-EMS application, whereas no corresponding significant effects were determined for the CG. Finally, the exceptionally high attendance rate of the WB-EMS group indicates excellent acceptance of this alternative training technology. The main limitations of this study, however, were the suboptimal evaluation methods of body composition that resulted from applying the gold-standard procedure “dual-energy X-ray absorptiometry” (DXA) in TEST II and III.
Study 2
Training Und Electromyostimulation Trial II (TEST II) [9]
Motivation and Study Aim
The primary goal of TEST II study was to determine the effect of WB-EMS on body composition in males with the metabolic syndrome 65 years and older. Our hypothesis was that WB-EMS training was significantly more favorable for positively affecting (a) (appendicular) muscle mass, (b) body fat mass, and (c) muscle strength/aerobic capacity compared with whole-body vibration training (control group).
Methodology
The TEST II study is a randomized, controlled, single-blinded intervention study over 14 weeks. The study was conducted from March to October 2009 at the Institute of Medical Physics (IMP) of the FAU.
Study Endpoints
Appendicular skeletal muscle mass (ASMM)
Abdominal (AF) and total (TF) body fat mass
Maximum isometric strength of the trunk and leg extensors and maximum aerobic capacity (VO2peak)
Participants
After applying the inclusion criteria, (a) male, age 65–75 years; (b) metabolic syndrome according to International Diabetes Federation [23]; and (c) largely untrained with respect to strength and endurance training ( < 1 h/week) and exclusion criteria for WB-EMS (above) and WBV application (e.g., endoprostheses, retina diseases), 28 men were enrolled in the study (Fig. 11.1). Stratified for age, participants were randomly assigned to the groups “WB-EMS” (n = 14) and “WB-vibration (WBV)” (n = 14). Table 11.4 gives the initial characteristics of both groups.
Table 11.4
Baseline characteristics of the TEST II study group
Variable | WB-EMS (n = 14) (MV ± SD) | WB-vibration (n = 14) (MV ± SD) |
|---|---|---|
Age [years] | 69.1 ± 2.7 | 69.7 ± 3.0 |
BMI [kg/m2] | 28.1 ± 4.4 | 27.6 ± 2.7 |
Lean body mass (LBM) [kg]a | 64.4 ± 6.1 | 61.7 ± 6.5 |
Energy intake [MJ/day]b | 11.02 ± 2.41 | 11.23 ± 2.30 |
Vitamin-D intake [μg/day]b | 4.8 ± 4.1 | 5.4 ± 4.4 |
Exercise volume [min/week]c | 32 ± 27 | 29 ± 31 |
Intervention
While the WB-EMS group performed the 15-min WB-EMS protocol (see above) every fourth to fifth day for 14 weeks, a 15-min WB-vibration training with a corresponding training frequency was implemented for the control group. The focus of the WBV exercise program which included low-amplitude movements was on improving flexibility and—to a lesser degree—strengthening. The WBV was performed on Vibrafit devices (Solms, Germany) which applied vertical vibration at a frequency of 30 Hz (amplitude, 1.7 mm). Using video animation mainly, stretching exercises were performed. Some slight squat movements were also be performed on the plates with a perceived exertion of moderate (4–5 on the Borg cr10 scale [15]). After an initial introduction of two to three sessions, vibration training was no longer fully supervised but regularly controlled by research assistants instead.
Measurements
Anthropometry
Body height, weight, and circumference values of the participants were measured using calibrated devices. Total and regional body fat and lean body mass were determined using a whole-body DXA scan (Hologic QDR 4500a, Discovery-upgrade, Bedford, MI, USA). The segmentation of the appendicular skeletal muscle mass (ASMM) was conducted according to Heymsfield et al. [24]. The abdominal “region of interest” (ROI) was set at between the upper end of the iliac crest and the lower edge of the lumbar spine.
Procedures for the measurement of isometric strength and the design of the questionnaire are comparable to the TEST I procedure and thus have been omitted here. In addition, maximum isometric power of the leg extensors (“leg press”) and plyometric jumps was assessed using a force plate (MTD-Systems, Neuburg v. Wald, Germany). The maximum oxygen uptake (VO2peak) (Oxycon mobile, Conshohocken, USA) of the subjects was determined during a cross-trainer step test, in which the resistance was increased by 20 Watt every 3 min at a constant frequency of 120–130 rpm up to a voluntary maximum.
Statistical Procedures
The formal sample size analysis of the study was based on the study endpoint “appendicular skeletal muscle mass” (ASMM). In contrast to the original publication [9], the data for this article were calculated using a “completer analysis,” where all cases with follow-up data were included.
Results
Only one participant (WB-EMS) could not be included in the final analysis, because cardiac risk factors that precluded participation were detected after the randomization procedure. Attendance rates in the WB-EMS group were 78 ± 8% and 72 ± 10% in the WBV group. The mean overall intensity of the EMS application over the intervention period was rated “hard” to “very hard” (6.1 ± 0.4 on the cr10 Borg Scale [15]), while the WBV group perceived their exercise program as being significantly less intense (4.7 ± 0.6).
Table 11.5 shows the results for the appendicular skeletal muscle mass (ASMM) and also for total (TF) and abdominal fat mass (AF). ASMM (and LBM) and TF differ significantly between the groups, with more favorable changes in the WB-EMS group. Differences for the AF did not reach significance, however. Unfortunately, a relevant reduction of body fat and muscle mass induced by energy restriction (−500 or −750 kcal/day for 4 or 6 weeks) in two participants of the WBV group may slightly confound our results.
Table 11.5
Baseline values, intragroup changes, and intergroup differences for body composition
WB-EMS (MV ± SD) | WBV (MV ± SD) | Difference MV (95% CI) | p | ES | |
|---|---|---|---|---|---|
Appendicular skeletal muscle mass (ASMM)[kg] | |||||
Baseline | 29.73 ± 2.48 | 26.66 ± 3.06 | – | – | – |
Difference (p) | 0.270 ± 0.433 (0.037) | −0.287 ± 0.642 (0.119) | 0.557 (0.131–0.982) | 0.012 | 1.02 |
Abdominal body fat (AF)[g] | |||||
Baseline | 3820 ± 1368 | 3765 ± 1792 | – | – | – |
Difference (p) | −237 ± 197 (0.001) | −91 ± 224 (0.153) | 146 (−18 to 310) | 0.079 | 0.69 |
Total body fat (TF)[%] | |||||
Baseline | 25.95 ± 3.49 | 27.37 ± 5.65 | – | – | – |
Difference (p) | −1.25 ± 0.93 (0.001) | −0.42 ± 1.12 (0.118) | 0.83 (0.05–1.64) | 0.037 | 0.81 |
Maximum isometric strength of the trunk and leg extensors and power of the leg extensors (leg press) significantly increased by 12% (leg extensor power) to 21% (leg extensor strength) (p = 0.001) in the WB-EMS group, while for the WBV group, only slightly positive changes (3% to 7%, p > 0.081) were observed. For all strength/power parameters, significant intergroup differences were determined. VO2peak increased by 4.3 ± 3.0% (p = 0.001) in the WB-EMS group, which was significantly more favorable (p = 0.003) compared with changes of the WBV group (−0.4 ± 3.1%, p = 0.633).
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