Electromyostimulation–a systematic review of the effects of different electromyostimulation methods on selected strength parameters in trained and elite athletes. J Strength Cond Res. 2012 Sep;26(9):2600-14. Filipovic A1, Kleinöder H, Dörmann U, Mester J.
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.
The above emphasis was mine. This is one of my favorite review papers on electric muscle stimulation (EMS), along with it’s brother paper that emphasized specific EMS parameters found to be most effective at increasing strength and sports performance. What’s interesting is that, like exercise, the principles between sports performance and physical therapy are almost identical. This paper should be a must-read for physical therapists, as electric stimulation seems clinically out of fashion (with dry needling for whatever reason being the latest fad). Ironically, the science, technology, effectiveness, and inexpensiveness of EMS have never been better. For athletes and patients, trying is usually immediately believing. Still, you need to be set up on a machine that can be programmed to proper parameters, using large comfortable electrodes, and you need to have a physical therapist who knows what parameters to use (here they are). Admittedly being hooked up to a circa 1990s TENS machine, or the typical physical therapy floor model combo machine with ultrasound, is a bit of a yawner. I’ll have to do an upcoming blog on what specific machines I like and don’t, because with electric stimulation technology you don’t always get what you pay for. The good news is that if you know what you are looking for, you can get a lot for a little.
I should point out that while the abstract in the above paper talks about whole-body EMS being time efficient, the paper itself describes whole-body EMS as less effective at increasing performance than localized EMS (and this agrees with the studies I have read as well). Otherwise the abstract is a pretty good summary of the paper.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.