STRENGTH IMPROVEMENT WITH ELECTROSTIMULATION

The relationship between muscle electrostimulation and strength has been studied for a long time. But can it really make you stronger?

In a classical way, it has been established that electrostimulation at medium and high frequencies manages to improve strength, from toning and firmness below 40hz, to even explosive force above 100hz. But it has also been shown that low-frequency electrostimulation can achieve improvements at the muscle level, even modifying the architecture (Deley and Babault, 2014).

One of the most important systematic reviews on strength and electrostimulation was published in several articles that perfectly describe the studies that have been carried out so far and the effects on strength parameters.

The first published part (Filipovic et. Al., 2011) includes articles that use both analytical and integral electrostimulation, describing their methodology. More than half of the selected studies had male subjects. The mean age was 22.8 years. All studies had healthy subjects with no history of injury. The interventions ranged from 10 days to 14 weeks, although in most cases the training lasted 4-6 weeks. The number of sessions ranged from 1 to 7 per week. In many of the interventions, electrostimulation was analytical, and the electrodes were placed on the lower limbs, especially on the quadriceps. In addition, almost all studies use isometric contractions and the parameters vary widely, from 20 to 120 hz.

This variety of articles, with protocols so different from one another, makes the body of evidence dispersed and does not allow us to make conclusive statements. It is difficult to include data in meta-analysis from which to draw conclusions also based on statistical results.

The second part (Filipovic et al., 2012) revealed that electrostimulation is effective in improving performance. In fact, after 3-6 weeks of training, the following improvements occur:

When this review was published there were only two articles indexed in PubMed on full body electrostimulation, however Filipovic and his colleagues did not have time to include them, so when he talks about full body EMS he refers to non-indexed studies. So this is what they indicated about Integral Electrostimulation:

“Compared to local EMS methods, the full body ones achieve less gains in maximal strength in the same period (2 sessions per week). In terms of speed and power strength parameters, full-body EMS did achieve notable gains in other strength parameters, such as impulse strength and rate of force development. However, in the field of full-body EMS, only few international studies are published, and therefore the results have to be considered with caution. […] Full body EMS showed significant increases in maximum speed for dynamic movements with additional weight (40% 1RM) in m. biceps femoris from trained subjects. In addition, a significant increase in the rate of force development and the driving force was shown. […] Studies with whole body methods have not shown a significant increase in jumping ability in the post-test phase. Compared to local EMS methods, these studies achieved lower strength gains in maximal dynamic strength for the quadriceps. “

Between 2010 and 2015, the Kemmler research group has published a series of articles, mostly referring to the elderly population, where it analyzes the adaptations of training with EMS Integral Activa. In Kemmler’s studies on the elderly population, the average of the subjects was around 70-75 years, except in the first “trial” where the average was approximately 65 years. This means that the adaptations to strength will be different due to the changes produced by age at the muscular, nervous, endocrine level, etc.: reduction in lean mass, decrease in muscular strength, mainly due to loss of motor units and muscle fibers, fewer type II fibers, loss of nerve cells in the brain, decreased brain weight,

All these changes mentioned, and many more, make adaptations to strength training occur in a different time and way than they would occur in active youth.

In the Kemmler studies the results were as follows:

In what we have called studies I and II, the intervention weeks were 14, while in IIIa and IIIb it was 54 weeks. I included postmenopausal women, II sedentary men with metabolic syndrome, and III sedentary elderly with risk of sarcopenia.

The results of maximum isometric force of the leg extensors are in line with those of other studies, such as those of Cannon and Marino (2010), Galvão and Taaffe (2005), where the improvements of resistance resistance training are evaluated in older people.

What can we conclude?

Electrostimulation can be effective in significantly improving strength, explosive strength, jumping ability, speed, and power. Active Integral EMS also manages to improve strength as the latest research has indicated, although studies are still lacking to increase our knowledge in this regard.