I have developed hip pain in my leading hip over the past few months of form work. I wanted to share some thoughts about it since I believe it is due to a common problem found among amateur throwers. The red squares below highlight a problematic and similar hip position in two amateurs (the "Bad_Brace" is me, with the screenshot taken right after the release, at what I believe is the apex of the problem. I have included a video as well). It seems like rounding and pulling through, caused by poor weight shift (among other things, probably), is causing extreme internal rotation of the femur. The torso spins around ahead of the plant leg, causing the pelvis to externally rotate against the planted leg, causing the femur to internally rotate beyond the limits of natural flexibility. If you look at Simon, it looks like his hip (pelvis?) is still internally rotated at time of picture. Same with Paul. Their hip and femur seem to rotate together, as they rotate dynamically balance over the plant leg, leveraged off of the ground. It's almost as if rotation occurs "from the ground up", as a result of the natural forces at play. For me, rotation is happening from the torso down. Notice how my torso is completely facing targetward as my plant foot is just barely beginning to rotate. Yikes. Back to hammer throws it is.