By Prof. Dr. Dirk Fritzsche

Dear EMS fans,

I have been asked many times recently about whether EMS training could in any way be harmful. A recent article on Spiegel-Online was looking into serious damage that could be caused to the kidneys through EMS training (Link to article on Spiegel online).

I would like to provide a clear statement on the issue and clarify the background for all those who are unsure.

Muscle building exercises work by initially stimulating and contracting a portion of the muscle fibres and the muscle breaks down as a result due to the over stimulation. The body responds by building more muscle fibres which are better capilliarised (training effect). The muscle ‘organs’ have improved performance and utilise oxygen better. Through EMS training it is now actually possible to increase muscle contraction almost limitlessly using varying current levels without any willpower or effort required on your part. I have come across heart patients in my practice who were no longer able to train due to their condition but EMS training gave them the option and a great deal of encouragement. A small number of them turned up the power really high during an unsupervised moment because they wanted to get results even quicker. In 2 patients there was actual damage to the muscles which went above and beyond simple muscle fatigue.

What happened? The over-exertion of the untrained muscles led to a higher rate of cell damage in the muscle fibres. There was an increase in the muscle-specific creatine kinase enzyme in the blood due to cell degeneration. Furthermore, free myoglobin crossed over into the bloodstream.

Creatine kinase is a good marker for muscle straining/damage in the blood.

Myoglobin can lead to blockages in the renal tubes if it is found in large quantities.

This can result in temporary kidney damage. In extreme cases, it can even lead to ‘crush syndrome’ where the kidneys are hardly able to filter anymore.

Moreover, such bodily states occur fairly regularly in high performance sports: crush syndrome is well documented in the field of kick-boxing and wrestling, for example, but here it is the musculature that sustains the trauma.

Fact: The possibility of bodily harm is real and has been observed in unfit individuals as well as very enthusiastic (young) patients.

But in none of the cases was the damage permanent or even complex.

I’d like to give you this rule of thumb: Train enough to exert yourself but ensure that you can still breathe during the stimulation phase,

don’t overdo it (especially at the beginning)!

My recommended weekly ‘dosage’ for non-sports people is 2 x 20 min EMS strength training accompanied by 2 x 20 min EMS-supported cardio training and should not be exceeded.