Sports Performance Bulletin looks at recent research on how athletes can maximize their rate of recovery during or following sessions involving very hard or maximal efforts MORE
EMS: Time to plug in for fitness?
John Shepherd looks the scientific evidence for electrical muscle stimulation, and whether athletes could use it not just for recovery, but for fitness gains too
Electric muscle stimulation (also known as EMS) is a procedure where a carefully controlled electric current is sent through muscles in order to make them contract. This is achieved using a device to produce the electrical current, which is delivered to small electrically conducting pads. These are attached to the skin at specific positions in order to target and stimulate certain muscles.
Traditionally, EMS has been used for pain relief and during the injury rehabilitation process. When muscles contract as a result of EMS, the patients typically experience reduced pain and tension, and a reduction in swelling. EMS is therefore useful for those who are working to recover from an injury, because it can actually speed up the recovery process. However, as we shall see, more recent research suggests that EMS devices could be used to increase strength and performance. And with many athletes currently experiencing lockdown and unable to perform high-quality strength work, this could be a good time to explore what EMS has to offer.
The power of EMS
Contemporary EMS devices can be used to aid performance, for recovery and reduce pain. These devices – such as the Nurokor MiTouch (see figure 1) can have produce two key effects:
- #A neuromuscular effect, stimulating muscle tissue to contract whilst targeting the largest of fast twitch muscle motor units without conscious effort on the part of the user.
- #A peripheral nerve stimulation effect, which can target inflammation and boost recovery at a cellular level.
The strength of these signals (pulses and waveforms) can be made more relaxing for recovery purposes or very strong (although the strength can be varied) for sports performance enhancement. However, this can require some will-power to tolerate the on-off grip of the involuntary muscle stimulation created by EMS!
Figure 1: Example of an EMS device
Device shown here is the NuroKor Mi Touch. The pads are fixed to the skin at specific locations to target the activation of a particular muscle group.
EMS trades on the fact that our muscles react to electricity. In an athletic context, one of the first exponents to detail its use was Charlie Francis, coach to Ben Johnson and other Canadian athletes in the 1980s. However, prior to this, its use is documented with Soviet athletes in the fifties. Despite ‘doping’ his athletes, Francis was very much an innovator when it came to training theory, making sure that no stone was left unturned when it came to improving performance. As Francis himself said of EMS: “My own results have been so favourable that I am not interested in debating whether or not EMS works but rather in optimising the use of EMS in the training of elite athletes.”
Francis’s argument was that used correctly, EMS is able to creates an involuntary muscle contraction, stimulating recruitment of maximal amounts of muscle fibre – and the motor units which control them. Additionally, it is able to target fast twitch fibers preferentially. This is the reverse of ‘man-powered’ weight training, where smaller, slow twitch fibers are used preferentially initially. Only if there is sufficient stimulatory and outcome needs – ie to lift a heavy weight – are increasingly larger motor units and bundles of fast twitch muscle fibers recruited via significant neural input.
Researchers publishing in the Journal of Strength and Conditioning Research carried out a review study (a study that pools findings from a number of previous studies) on EMS in 2012. The researchers identified the type of EMS used, and the most relevant parameters for improvement for high performance sport – eg speed, strength, power and jumping and sprinting ability [J Strength Cond Res. 2012 Sep;26(9):2600-14]. They also identified three types of users – non-athletic populations, trained subjects and crucially elite performers (they placed a specific focus on the elite). Overall, they concluded that EMS is effective for developing physical performance. In particular, they team noted that after a stimulation period of 3-6 weeks, significant gains were shown in maximal strength (isometric force up by 58.8%; dynamic force up by 79.5%). In terms of specific sports improvement, they found the following:
- #Vertical jump height increased by 25%
- #Squat jump height increased by 21.4%
- #Countermovement jump height increased by 19.2%
- #Drop jump height increased by 12%
- #Sprint speed was increased by up to 4.8% in trained and elite athletes.
The team concluded: “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 increasing use in high-performance sports.”
The comments on ‘motor abilities ‘ are relevant here and tie in with the thoughts of coach Francis who stated: “It helps an athlete learn how to recruit and fire greater numbers of muscle fibre, for example, if you are having trouble learning how to wiggle your ears – incorporate EMS stimulation of the desired muscles into your training. You will not only learn to fire the intended muscle group but also greater numbers of motor units within that muscle.”
Francis also quoted research indicating that relatively few sessions were needed to achieve substantial speed and power gains – and this is something which seems to be vindicated by much more contemporary research. Researchers in the Journal of Strength and Conditioning from 2011 looked at EMS training using a current sufficient to produce around 60% of maximum voluntary contraction (MVC) [J Strength Cond Res. 25(11):3218-38]. They found that training regimens of around just four weeks, training three times per week for around 15-20 minutes was very effective for developing maximal strength, speed strength, jumping and sprinting ability and power. The exact protocol used was as follows: 6 seconds per contraction, 20% duty cycle, impulse width 306.9 microseconds, impulse frequency 76.4Hz, impulse intensity 63.7mA.
This is difficult information to potentially process. But we can simplify it by considering some research in the Journal of Strength and Conditioning Research from 2017, which looked at the application of EMS in trained athletes and sprint performance [J Strength Cond Res. 2017 Jun;31(6):1577-1584]. Their protocol improved standing start 10m performance by 5.3% and flying 10-metre times by 4.7%. The protocol used was:
- #Ten EMS cycles up to the maximal tolerated intensity applied every other day to the foot flexion muscles (sole and calf muscles).
- #Stimulation periods of 10 seconds and recovery periods of 50 seconds.
- #The above carried out for three weeks.
This research adds credence to the idea that very quick gains can be made from EMS. It also happens that Francis used a similar protocol, and based his approach on Soviet modalities which used short duration EMS training phases – for example 10-15 treatments. Francis is one of the few coaches to have publicly shared his EMS training protocols and these also follow the 10sec on 50sec off methodology with a 3-4 times a week frequency. He also identified the key muscle groups that should be targeted:
- #Lower back
EMS and CNS
Francis additionally recommended that EMS should be the final session of the day and that it should be preceded by a basic warm-up involving dynamic movements. He also pointed out that as EMS involuntarily creates muscle contractions, there is no equivalent ‘fatigue drain’ on the central nervous system. EMS could therefore offer another potential plus in that it can be used to continue high-intensity training without draining the CNS. This would be useful, for example, during the competitive phase when strength levels need to be maintained. The normal way to do this would be via using near maximal lifts (albeit with few reps). However, this would require a significant CNS contribution on the part of the athlete and therefore add to fatigue drain across a training phase.
Practical considerations and cautions
Hopefully, this overview of EMS with its focus on how it works and some of the training protocols for use will stimulate coaches and athletes to look into this training method. We have carbon-fiber plate shoes that enhance performance, but EMS has been around for longer than Nike and perhaps could enhance performance even more significantly!
Athletes and coaches should however note that EMS machines for enhancing performance should not be deployed until they understand how they work and the protocols that best work. As with any new training method, EMS needs to be introduced carefully and progressively. Also, there should be breaks from EMS use within a periodized training plan. Note also that EMS machines such as the Nurokor MiTouch enable multiple muscles to be worked at the same time. It’s important to realize that muscle extensors and flexors (eg quads and hamstrings) should NOT be stimulated at the same time.
Author’s note: There are a number of good EMS devices out there, but I have personally experienced excellent results with the NuroKor Mi Touch (shown in figure 1). For a direct link to this product please visit: NuroKor Mi Touch
John Shepherd is a former international athlete and regular Sports Performance Bulletin contributor. As a high-performance coach, he has coached for England, Ireland, and many county associations. Athletes he has coached have won European titles. Shepherd is also the author of numerous books such as Strength Training for Women, Strenth Training for Running and the Complete Guide to Sports Training.
For more info, visit: johnshepherdfitness.com & on YouTube “JohnShepherdtrack&fieldcoach”