I have attended several seminars with both Kevin, Val and Vladimir Vasiliev and have been hit by all of them. The only way to describe it is to imagine being hit extremely hard with little effort and the energy expanding inside you internally like a grenade going off. I have always hit with the intention of exploding the energy inside the body but Systema takes it to another level. When you hit like this "correctly" the energy doesn't come back into your shoulders and neck which is a good thing. At these seminars these guys will hit you only as hard as you desire to be hit.....I asked for more at one of them with Val and got the strike of a lifetime into the solar plexus. I felt the strike inside my organs for over 30 minutes even with Val trying to work the energy around. The wave looks long to start with but after weeks of practice you wont even notice it anymore as it will become second nature. You will also find that you utilize the wave on every strike and even blocking and throws. It becomes an instinctive part of everything you do.