During traditional strength training, the brain sends bioelectrical impulses which cause certain muscles to contract. However, not all muscles have a well-developed connection to the brain, and these muscles are not as easily activated, therefore they will not develop so well. This way we can never train with full force, even if we want to.
EMS (electrical muscle stimulation) however, with low-strength electrical impulses, directly stimulates our deep muscles thus deceiving our body’s natural reactions and training almost 100% of our musculature.
EMS training is a completely safe form of working out and as such, it has been used for medical and rehabilitation purposes for a long time