I do martial arts as well and the easiest way to go would be to take a hot bath and directly after stretch your muscles as far as you can.\nTheory here is that all your muscles will be heated up (not just the ones you try and warmp up through various stretching excersises).\nIt does take a couple of weeks to go completely flat.\nTry going down as far as you can and keep that position for as long as you can before getting up. the muscles have to become used to a stretched position.