A month ago, I saw something new. A guy was doing a deep squat mobility exercise, then he grabbed his toes from the front, and pulled up. As a consequence of pulling on his toes, his lower back went into a deeper flexion. Technically speaking, he was making an open chain exercise into a closed chain exercise. I've been going to gyms for thirty years, and I've never seen anyone do this before. Then I saw another person doing it, and then another person today, at the same gym. My conclusion is that some fitness guru, probably on youtube, is telling people this is a good idea. Does anybody know what fitness guru would be recommending you grab your toes during a deep squat? Is it a crossfit thing?