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EMS training is becoming more and more popular. Practical experience shows it to be effective and safe. In fact, the effects of EMS training are also very well documented and training successes have long been proven. For many years now, the University of Erlangen under the direction of Prof. Dr. Kemmler has been researching the application possibilities of whole-body electromyostimulation (EMS). 

Professor Dr. Kemmler, how does the general effectiveness of “whole-body EMS” relate to other forms of (strength) training?


Whole-body electromyostimulation (EMS) can indeed be clearly located in the area of strength training. A corresponding comparison of our working group with a HIT protocol, i.e. an application training up to the muscular load (MF+), showed comparable results for an increase in muscle mass, a reduction in body fat as well as the strength of the holding muscles with slightly less favourable data for leg strength. However, the time required to achieve these results was only half with whole-body electromyostimulation.


The press often speaks of "training without effort" in connection with EMS. What do you think of this statement?


I don't think that statement is true. Admittedly, with the current fitness oriented EMS method variant, the relatively intensive current application with only moderate arbitrary load apparently "does the job". As with almost all other types of stress, the appropriate stimulus level of the stress, i.e. the (current) intensity of the EMS, is the central success criterion. In training practice, this means that in close interaction between trainer and user, an appropriately high stimulus intensity must of course be applied, which can and should be perceived as "strenuous". Especially for less sporty EMS users with a correspondingly weak sense of stress, this introduction to an appropriately high level of stress is the trainer's central "challenge".


Critics see the "artificial" activation during EMS training as affecting only muscle mass and less coordination and everyday functions. How do you see this?


With a purely passive EMS application this argument undoubtedly applies. In fact, the hypertrophic effects of a passive EMS on muscle mass are about as high as those of a dynamic workout with low voluntary activation of the muscles. However, the more complex a movement task becomes, the smaller are the effects of a passive EMS. In training practice, WB-EMS is therefore always carried out in dynamic mode, i.e. with additional voluntary activation. Incidentally, this is where competitive sport differs from preventive / fitness oriented application. While in competitive sports a high arbitrary activation with a moderate current intensity prevails, which allows an absolutely correct discipline-specific execution of the movement, the classical fitness oriented EMS method variant rather focuses on the current component. In older people who have to positively influence the muscle and fat mass in addition to (functional) training goals such as general coordination or everyday function, a mixed training of both methods ideally appears to be periodically ideal with hypertrophically oriented and functionally oriented sections.


Is EMS training dangerous?


If used correctly and with permanent support, definitely no. If the contraindication is observed, if adequate preparation for the training session is made and if scientific training principles are applied sensibly, EMS training is (still) safer from a metabolic and musculoskeletal point of view than conventional strength training on equipment. The "hair-raising" high creatine kinase and myoglobin levels reported in the past and also confirmed by us are based on a completely excessive intensive current application during the initial units. Translated into conventional strength training, this would be like imposing a HIT training protocol on the strength training novices in the first training session with all the sophisticated intensity strategies including the emphatically overthreshold eccentric execution - the difference to EMS, however, is that not a maximum of 2-3 muscle groups are activated simultaneously, as in strength training, but all the large muscle groups, so the extent of muscular overload and damage is much higher. (...)


The University of Erlangen has been researching EMS for almost 10 years and has played a major role in the recommendations for safe use. In your opinion, what are the most important rules of conduct that a provider of EMS training must observe?


From our point of view, effectiveness and safety of the application are clearly in the foreground. As already discussed above, EMS is not an effective self-runner at all times. In fact, even more than with other forms of training, the close and trusting interaction between the user and the provider in order to generate the best possible stimulus level is the central characteristic of a successful training. For this reason, we see a maximum of 2 trainees per trainer as a critical limit. Even an experienced user should not train without a trainer. In addition, an appropriate sports scientific training of the provider / trainer is important in order to ensure long-term success and to address changing training goals through the training principles that can be applied in this area of tension, such as variations, cyclisation and periodisation of the training. With regard to safety, a first guideline was issued, which addresses aspects such as preparation and follow-up of the EMS training, specifications for intensity control / load and, above all, close supervision by a well-trained trainer. As far as contraindications are concerned, the development is certainly not yet complete. For example, tumor diseases that were seen as absolute contraindications in the past are now being used in a scientific / clinical environment. On the other hand, diseases or conditions in which the sensitivity can be impaired due to a too high current intensity due to a lack of feedback from the user can be viewed critically. Here, we hope to improve safety through education and cooperation with physicians by better assessing the EMS-specific risk profile of the participant.


What must / should users know about EMS, what should I consider, which exclusion criteria apply?


Without a doubt, EMS, correctly applied, is a very time-efficient option for improving musculoskeletal, functional and (slightly less prominent) cardiometabolic parameters. Although the minimum, effective dose of training frequency / duration in EMS is, as already discussed, quite low, only regular and, above all, long-term participation makes sense. I think in the course of the interview it has already become clear that EMS is a serious form of training that requires proper preparation and follow-up in order to work effectively and safely. This includes, among other things, sufficient fluid intake before and immediately after training, adequate protein intake to generate muscular adjustment processes and ensuring a good physical situation and willingness to perform for the training. Electrical implants, pregnancy or EMS application in the area of wounds, fresh scars or hernia are certainly to be regarded as absolute EMS specific exclusion criteria. Of course, with EMS it is possible not to use some electrons and thus to save locally affected regions. However, in case of uncertainty as to whether a EMS application is possible, the physician who ideally cooperates with the provider and is familiar with EMS must remain the decisive authority. This is also where the TÜV certification of the operators comes in, which requires a cooperating, knowledgeable physician - in our view a real improvement of the situation.


EMS training is often addressed as time-saving training for high-income earners. In recent years, they have conducted studies with a wide variety of target groups. Who do you think is the actual target group for whole-body EMS training?


Admittedly, the current EMS setting as "Personal Training" contains a decisive success factor on the one hand and a considerable cost factor on the other; however, this aspect is relativized by the low training frequency. In this respect, EMS seems to us to be the cheapest PT variant at all. With regard to the range of applications, EMS can be applied as a time-effective and joint-gentle training measure at least as comprehensively as conventional strength training. However, we see EMS predominantly as an option for people who cannot or do not want to do conventional, intensive strength training for various reasons. Within our research projects, we have specialised centrally in musculoskeletal and cardiometabolic diseases or conditions of (mostly) old age. Of course, other target groups and areas of application are also conceivable and meaningful. Here we would like to conduct WB-EMS research via a research network with other institutions, identify important application areas and evaluate them jointly in the future. I think the WB-EMS research will develop internationally more prominent in the next years, so that we can expect still exciting research results to this topic.


Is it possible to lose weight through EMS training?


Yes, definitely - only moderately, but all the more sustainably. Unfortunately, the scales at home provide little evidence of this, since the reduction of body fat is almost compensated by the increase in muscle mass. This effect is similar to an intensive strength training, while for an isolated endurance training or an energy-restrictive diet a reduction of muscle and fat mass in the ratio 1-4 or 1-3 is reported. In this context, I consider it very important that a muscle-preserving component is taken into account in weight management via energy restriction or endurance sports. Here EMS is certainly a time-effective option, which should ideally be combined with compensatory protein administration. If one addresses the extent of body fat reduction via regular EMS application, robust measurement methods show a EMS-induced decrease in body fat mass in the range of 1-1.5 kg after 10-12 weeks. Of relevance is that this effect is particularly prominent for abdominal body fat. Magnetic resonance imaging shows an above-average reduction of cardiometabolically highly relevant intraabdominal body fat. In summary, the increase of muscle mass with simultaneous reduction of body fat mass is a central feature of WB-EMS. If one considers the paths through which EMS has an effect on energy turnover, the relevant mechanisms are not so much the acute load on EMS due to the low necessary training volume of EMS, but rather the increase in basic turnover due to the increase (and possibly metabolic activation) of muscle mass as well as a relatively high "afterburning effect" due to the necessary regeneration and adaptation effects of EMS training.


The heart is also a muscle. Why is the heart not influenced by the electrical impulses of electromyostimulation?


Like any muscle, the heart muscle contracts when electrical signals depolarize the muscle fibers above a certain threshold. In this way, the autonomous conduction system causes the heart to rhythmically contract. In principle, the heart muscle can also be influenced or disturbed by external currents, as can be the case in an electrical accident or a resuscitation with a defibrillator. In contrast to sockets or defibrillators, which generate very high voltages and currents, whereby the current flows through the entire body, WB-EMS has a very low current intensity and the current flow is regionally limited. This is because extremely low currents are sufficient to activate the skeletal muscles. The main effect of electromyostimulation with low-frequency currents is the activation of the small motor nerve branches near the electrodes. If these are depolarized by the external current above a certain threshold, the nerves generate an action potential which automatically continues in the direction of muscle fibers and activates them. Because the external current "triggers" the body's own physiological excitation conduction, the musculature is also activated at depth and stimulated to strong contraction. However, there is no relevant current flow outside the skeletal muscles through the chest to the heart. Nevertheless, cardiac arrhythmias and pacemakers in particular are contraindications, which should be strictly adhered to for reasons of caution.


For some years now, functional training has been regarded as a highly effective method of achieving fitness goals quickly and effectively. How do you see the connection/difference to EMS training?


The comparison is actually interesting: Functional training is often presented as the exact opposite of EMS, since exercises with complex movements over several joints and muscle groups are the focus, whereas for WB-EMS, at least in the past, the aspect of statics and non-functionality was always in the foreground. Now modern EMS is rarely applied statically (see below), but predominantly dynamically. When training EMS we prefer movements relevant to everyday life over several joints and as far as possible large amplitude. In order to generate the necessary overthreshold intensity, the Functional Training uses different additional loads, in the EMS the intensity is primarily regulated by the current impulse. The latter aspect contributes to more favourable orthopaedic compatibility and less risk of injury through EMS, especially for beginners and less athletically trained persons. Ultimately, both training methods are certainly effective, but their ideology is different and somewhat incompatible. Aspects such as low time budget, health orientation / health limitations, low affinity to conventional training and excellent intensity control speak in favour of EMS training in this context.


However, there are different methods and opinions for the implementation of EMS training. How important is the "exercise" for the training result?


The question as to the relevance of the exercise for the training result depends to a large extent on the training objective. While in our investigations with chronic back pain patients we have performed static exercises or movements with low amplitude (successfully), the relevance of the exercise in terms of movement execution for the functionality (see above) is high. A recent study showed that after 12 weeks of passive vs. active EMS application in a lying position, with relevant strength increase rate in both groups, twice as much improvement of the hip and leg extensors musculature was achieved by the active group. Therefore, in all groups with the primary or secondary training goal, we perform light physical exercises that are not per se adequate to trigger muscular adjustment symptoms. Our colleagues from (high) performance sports often follow a different philosophy in this context. Here, discipline-specific exercises with a high arbitrary stimulus level are often performed, which are further intensified by adjuvantly applied WB-EMS. In flapsy terms, the athlete himself does the majority of the job here, while in the classic WB-EMS the load is almost exclusively generated by the current application. As a result, one can conclude that light physical exercises in fitness and health-oriented  are certainly sufficient; complex and intensive (body) exercise forms under  should be reserved for competitive sports.


A supplement to the question with the exercises. How important is the use of additional load (TRX, dumbbells, etc.) during EMS training?


So a kind of combination of functional training or dumbbell/device training and EMS? I think this option is not appropriate with the few exceptions of high performance sports, in extreme cases even counterproductive. As already mentioned above, the central moment of the classic EMS is the effect of the current application on the muscles. In order to generate a training that is as effective as possible, an optimal stimulus intensity in the sense of an appropriate impulse strength must be generated. We all know that this is not quite trivial, but can ideally only be achieved through close and constant interaction between the trainer and the trainee. This means that the trainer should primarily take care of intensity control; vice versa, the participant must be able to correctly feedback the intensity of the current application; very complex physical exercises (see above) and/or additional weights are counterproductive for this process, since the participant can hardly assign the determining stimulus. Ultimately, one should also consider the skills and scope of the EMS. As health and fitness oriented researchers we see EMS as a safe and joint-gentle alternative for people who for various reasons have a low affinity to intensive strength training protocols.


Prof. Dr. Wolfgang Kemmler (24.01.64 in Tübingen) is Research Director at the Institute of Medical Physics at the Friedrich Alexander University Erlangen-Nuremberg. The training and sports scientist is a proven expert in training-scientific intervention research as well as in alternative training technologies with a focus on whole-body electromyostimulation.

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