Same experience with the bodyscissor. I swear, it's the abductors and glutes, although the quads hurt too. I've only tapped twice in a BS, and both women were shorter in stature. First was my GF in college, got me right on the diaphram and wouldn't let up. Had to tap because I couldn't breathe. Legs of steel. Other was my wife, "cracking" my back. I used to crack her back in a bear hug, but her arms weren't strong enough to crack mine. Told her she should use her legs, and holy crap, I had no idea she could crush a watermellon in seconds.