This is the first part of 2 studies that systematically review the current state of research and structure the results of selected electromyostimulation (EMS) studies in a way that makes accurate comparisons possible. This part will focus on the effects of EMS on strength enhancement. On the basis of these results, part 2 will deal with the influence of the training regimen and stimulation parameters on EMS training effectiveness to make recommendations for training control. Out of about 200 studies, 89 trials were selected according to predefined criteria: subject age (<35 years), subject health (unimpaired), EMS type (percutaneous stimulation), and study duration (>7 days). To evaluate these trials, we first defined appropriate categories according to the type of EMS (local or whole body) and type of muscle contraction (isometric, dynamic, isokinetic). Then, we established the most relevant strength parameters for high-performance sports: maximal strength, speed strength, power, jumping and sprinting ability. Unlike former reviews, this study differentiates between 3 categories of subjects based on their level of fitness (untrained subjects, trained subjects, and elite athletes) and on the types of EMS methods used (local, whole-body, combination). Special focus was on trained and elite athletes. Untrained athletes were investigated for comparison purposes. This scientific analysis revealed that EMS is effective for developing physical performance. After a stimulation period of 3-6 weeks, significant gains (p < 0.05) were shown in maximal strength (isometric Fmax +58.8%; dynamic Fmax +79.5%), speed strength (eccentric isokinetic Mmax +37.1%; concentric isokinetic Mmax + 41.3%; rate of force development + 74%; force impulse + 29%; vmax + 19%), and power (+67%). Developing these parameters increases vertical jump height by up to +25% (squat jump +21.4%, countermovement jump +19.2%, drop jump +12%) and improves sprint times by as much as -4.8% in trained and elite athletes. With regard to the level of fitness, the analysis shows that trained and elite athletes, despite their already high level of fitness, are able to significantly enhance their level of strength to same extent as is possible with untrained subjects. The EMS offers a promising alternative to traditional strength training for enhancing the strength parameters and motor abilities described above. Because of the clear-cut advantages in time management, especially when whole-body EMS is used, we can expect this method to see the increasing use in high-performance sports.

Our first review from our 2-part series investigated the effects of percutaneous electromyostimulation (EMS) on maximal strength, speed strength, jumping and sprinting ability, and power, revealing the effectiveness of different EMS methods for the enhancement of strength parameters. On the basis of these results, this second study systematically reviews training regimens and stimulation parameters to determine their influence on the effectiveness of strength training with EMS. Out of about 200 studies, 89 trials were selected according to predefined criteria: subject age (<35 years), subject health (unimpaired), EMS type (percutaneus stimulation), and study duration (>7 days). To evaluate these trials, we first defined appropriate categories according to the type of EMS (local or whole-body) and type of muscle contraction (isometric, dynamic, isokinetic). Unlike former reviews, this study differentiates between 3 categories of subjects based on their level of fitness (untrained subjects, trained subjects, and elite athletes) and on the types of EMS methods used (local, whole-body, combination). Special focus was on trained and elite athletes. Untrained subjects were investigated for comparison purposes. The primary purpose of this study was to point out the preconditions for producing a stimulus above the training threshold with EMS that activates strength adaptations to give guidelines for implementing EMS effectively in strength training especially in high-performance sports. As a result, the analysis reveals a significant relationship (p < 0.05) between a stimulation intensity of ≥50% maximum voluntary contraction (MVC; 63.2 ± 19.8%) and significant strength gains. To generate this level of MVC, it was possible to identify guidelines for effectively combining training regimens (4.4 ± 1.5 weeks, 3.2 ± 0.9 sessions per week, 17.7 ± 10.9 minutes per session, 6.0 ± 2.4 seconds per contraction with 20.3 ± 9.0% duty cycle) with relevant stimulation parameters (impulse width 306.9 ± 105.1 microseconds, impulse frequency 76.4 ± 20.9 Hz, impulse intensity 63.7 ± 15.9 mA) to optimize training for systematically developing strength abilities (maximal strength, speed strength, jumping and sprinting ability, power).

Exercise positively affects most risk factors, diseases and disabling conditions of middle to advanced age, however the majority of middle-aged to older people fall short of the exercise doses recommended for positively affecting cardio-metabolic, musculoskeletal and neurophysiological fitness or disabling conditions. Whole-Body Electromyostimulation (WB-EMS) may be a promising exercise technology for people unable or unmotivated to exercise conventionally. However, until recently there has been a dearth of evidence with respect to WB-EMS-induced effects on health-related outcomes. The aim of this systematic review is to summarize the effects, limitations and risks of WB-EMS as a preventive or therapeutic tool for non-athletic adults. Electronic searches in PubMed, Scopus, Web of Science, PsycINFO, Cochrane and Eric were run to identify randomized controlled trials, non-randomized controlled trials, meta-analyses of individual patient data and peer reviewed scientific theses that examined (1) WB-EMS-induced changes of musculoskeletal risk factors and diseases (2) WB-EMS-induced changes of functional capacity and physical fitness (3) WB-EMS-induced changes of cardio-metabolic risk factors and diseases (4) Risk factors of WB-EMS application and adverse effects during WB-EMS interventions. Two researchers independently reviewed articles for eligibility and methodological quality. Twenty-three eligible research articles generated by fourteen research projects were finally included. In summary, thirteen projects were WB-EMS trials and one study was a meta-analysis of individual patient data. WB-EMS significantly improves muscle mass and function while reducing fat mass and low back pain. Although there is some evidence of a positive effect of WB-EMS on cardio-metabolic risk factors, this aspect requires further detailed study. Properly applied and supervised, WB-EMS appears to be a safe training technology. In summary, WB-EMS represents a safe and reasonable option for cohorts unable or unwilling to join conventional exercise programs. However, much like all other types of exercise, WB-EMS does not affect every aspect of physical performance and health.

Red blood cell-nitric oxide synthase (RBC-NOS)-dependent NO production is essential for the maintenance of RBC deformability, which is known to improve oxygen supply to the working tissue. Electrostimulation of the whole body (WB-EMS) has been shown to improve maximal strength, springiness, and jumping power of trained and untrained athletes. To examine whether these 2 parameters are associated, this study, for the first time, aimed to investigate the effects of an 18-week dynamic WB-EMS program on RBC deformability in addition to maximal strength performance (1 repetition maximum [1RM]) in elite soccer players. Fifteen test persons were assigned in either WB-EMS group (EG, n = 10) or training group (TG, n = 5). Next to their weekly training sessions, EG performed 3 × 10 squat jumps under the influence of WB-EMS twice per week between weeks 1 and 14 and once per week between weeks 14 and 18. Training group only performed 3 × 10 squat jumps. Performance was assessed by a maximal strength test on the leg press machine (1RM). Subjects were tested at baseline and after weeks 7, 14, and 18 with blood sampling before (Pre), 15-30 minutes after (Post), and 24 hours after (24-hour Post) the training. The results showed that maximal strength was significantly improved in EG (p < 0.01). Maximum RBC deformability (EImax) increased on EMS stimulus in EG while it remained unaffected in the TG. Acute increase in EImax at baseline was explained by an increase in RBC-NOS activation while chronic increase of deformability must be caused by different, yet unknown, mechanisms. EImax decreased between weeks 14 and 18 suggesting that 1 WB-EMS session per week is not sufficient to alter deformability (EImax). In contrast, the deformability at low shear stress (EI 3 Pa), comparable with conditions found in the microcirculation, significantly increased in EG until week 14, whereas in TG deformability only, increased until week 7 due to increasing training volume after the winter break. The results indicate that WB-EMS represents a useful and time-saving addition to conventional training sessions to improve RBC deformability and possibly oxygen supply to the working tissue and thus promoting general force components in high performance sport.

BackgroundThe improvement of strength and athletic performance during a competitive season in elite soccer players is a demanding task for the coach.AimsAs whole-body electrostimulation (WB-EMS) training provides a time efficient stimulation potentially capable in exerting skeletal muscle adaptations we aimed to test this approach over 7 weeks in trained male soccer players during a competitive season.HypothesisWe hypothesized that a superimposed WB-EMS will increase maximal strength and type I and type II myofiber hypertrophy.MethodsTwenty-eight male field soccer players were assigned in either a WB-EMS group (EG, n = 10), a training group (TG, n = 10), or a control group (CG, n = 8). The regular soccer training consists of two to four sessions and one match per week. In concurrent, the EG performed 3 × 10 squat jumps superimposed with WB-EMS twice per week, TG performed 3 × 10 squat jumps without EMS twice per week, and the CG only performed the regular soccer training. Muscle biopsies were collected and strength tests were performed under resting conditions before (Baseline) and after the intervention period (Posttest). Muscle biopsies were analyzed via western blotting and immunohistochemistry for skeletal muscle adaptive responses. To determine the effect of the training interventions a 2 × 3 (time ∗ group) mixed ANOVA with repeated measures was conducted.ResultsMaximal strength in leg press (p = 0.009) and leg curl (p = 0.026) was significantly increased in EG along with a small but significant increase in type II myofiber diameter (p = 0.023). All of these adaptations were not observed in TG and CG.ConclusionWB-EMS can serve as a time efficient training method to augment strength capacities and type II fiber myofiber growth in soccer players when combined with specific resistance training. This combination may therefore be a promising training modification compared to traditional strength training for performance enhancement.

Background: Whole-body electromyostimulation (WB-EMS) gained increasing interest in sports within recent years. However, few intervention studies have examined the effects of WB-EMS on trained subjects in comparison to conventional strength training.Objective: The aim of the present mini-meta-analysis of 5 recently conducted and published randomized controlled WB-EMS trails of our work group was to evaluate potentially favorable effects of WB-EMS in comparison to conventional strength training.Methods: We included parameter of selected leg muscle's strength and power as well as sprint and jump performance. All subjects were moderately trained athletes [>2 training sessions/week, >2 years of experience in strength training; experimental group (n = 58): 21.5 ± 3.3 y; 178 ± 8 cm; 74.0 ± 11 kg; control group (n = 54): 21.0 ± 2.3 y; 179.0 ± 9 cm; 72.6 ± 10 kg]. The following WB-EMS protocols were applied to the experimental group (EG): 2 WB-EMS sessions/week, bipolar current superimposed to dynamic exercises, 85 Hz, 350 μs, 70% of the individual pain threshold amperage. The control groups (CG) underwent the same training protocols without WB-EMS, but with external resistance.Results: Five extremely homogenous studies (all studies revealed an I2 = 0%) with 112 subjects in total were analyzed with respect to lower limb strength and power in leg curl, leg extension and leg press machines, sprint—and jump performance. Negligible effects in favor of WB-EMS were found for Fmax of leg muscle groups [SMD: 0.11 (90% CI: −0.08, 0.33), p = 0.73, I2 = 0%] and for CMJ [SMD: 0.01 (90% CI: −0.34, 0.33), p = 0.81, I2 = 0%]. Small effects, were found for linear sprint [SMD: 0.22 (90% CI: −0.15, 0.60), p = 0.77, I2 = 0%] in favor of the EMS-group compared to CON.Conclusion: We conclude that WB-EMS is a feasible complementary training stimulus for performance enhancement. However, additional effects on strength and power indices seem to be limited and sprint and jump-performance appear to be benefiting only slightly. Longer training periods and more frequent application times and a slightly larger stimulus could be investigated in larger samples to further elucidate beneficial effects of WB-EMS on performance parameters in athletes.

Intramuscular density of monocarboxylate-transporter (MCT) could affect the ability to perform high amounts of fast and explosive actions during a soccer game. MCTs have been proven to be essential for lactate shuttling and pH regulation during exercise and can undergo notable adaptational changes depending on training. The aim of this study was to evaluate the occurrence and direction of potential effects of a 7-weeks training period of jumps with superimposed whole-body electromyostimulation on soccer relevant performance surrogates and MCT density in soccer players. For this purpose, 30 amateur soccer players were randomly assigned to three groups. One group performed dynamic whole-body strength training including 3 x 10 squat jumps with WB-EMS (EG, n = 10) twice a week in addition to their daily soccer training routine. A jump training group (TG, n = 10) performed the same training routine without EMS, whereas a control group (CG, n = 8) merely performed their daily soccer routine. 2 (Time: pre vs. post) x 3 (group: EG, TG, CG) repeated measures analyses of variance (rANOVA) revealed neither a significant time, group nor interaction effect for VO 2 peak, Total Time to Exhaustion and La max as well as MCT-1 density. Due to a lack of task-specificity of the underlying training stimuli, we conclude that seven weeks of WB-EMS superimposed to jump exercise twice a week does not relevantly influence aerobic performance or MCT density.

Red blood cell nitric oxide synthase (RBC-NOS) dependent NO production positively affects RBC deformability which is known to improve oxygen supply to the working tissue. Whole-body electrostimulation (WB-EMS) has been shown to improve maximum strength, sprinting and jumping performance, and to increase deformability in elite soccer players during the season. The aim of the present study was to investigate whether WB-EMS affects RBC turnover which might affect overall deformability of circulating RBC by rejuvenation of the RBC population and if this might be related to improved endurance capacity. Thirty male field soccer players were assigned in either a WB-EMS group (EG, n = 10), a training group (TG, n = 10), or a control group (CG, n = 10). EG performed 3 × 10 squat jumps superimposed with WB-EMS twice per week in concurrent to 2–4 soccer training sessions and one match per week. TG only performed 3 × 10 squat jumps without EMS in addition to their soccer routine and the CG only performed the usual soccer training and match per week. Subjects were tested before (Baseline) and in week 7 (wk-7), with blood sampling before (Pre), 15–30 min after (Post), and 24 h after (24 h post) the training. Endurance capacity was determined before and directly after the training period. The key findings of the investigation indicate an increase in young RBC in the EG group along with improved overall RBC deformability, represented by decreased SS1/2:EImax Ratio. Analysis of the different RBC subfractions revealed improved RBC deformability of old RBC during study period. This improvement was not only observed in the EG but also in TG and CG. Changes in RBC deformability were not associated to altered RBC-NOS/NO signaling pathway. Endurance capacity remained unchanged during study period. In summary, the effect of WB-EMS on RBC physiology seems to be rather low and results are only in part comparable to previous findings. According to the lower training volume of the present study it can be speculated that the soccer specific training load in addition to the WB-EMS was too low to induce changes in RBC physiology.