I seem to have quite tight hip joints (or not sure if they are the joints themselves, or muscles around the joint area). For example - when I try to do the swivel hips mobility/stretch from the Foundation 1, I cannot believe for the life of me that I would be actually able to turn my legs to a point where both knees are on the ground, while keeping my glutes on the ground as well. The problem is not the leading leg - if I am tilting the legs towards left, the left leg will get it's knee to ground without problems, but after the opposite leg's knee goes past the hip joint, the struggle begins. It feels like the joint itself gets to a point it just doesn't want to move beyond, and the lock feels such that it's not a matter of stretching muscles / tendons, it feels more like a definitive wall, almost like a bone hitting a bone and no question about going forward anymore. So the position I end at when I am the very farthest position available is such that my leading leg is in a correct position, but the opposite leg is in a position where the knee is still pointing almost straight up, in a 75-80 degree angle from the ground, if 90 degrees is straight up. If I allow the right side glute to raise up, I can make the angle to 45, but no further. What would be reasonable techniques or things I could try to get this lock opened in addition to swivel hips move? I think this kind of tightness really affects some of my basic movements quite a bit, and it's weird because in many other directions and positions I am very flexible (I can do normal front split and manage to do quite a many yoga positions without any trouble). Here are two pictures of the end position: EDIT: I thought that a stretch presented in this video at 3:00 might be good addition: