Does anybody do them?
If so, do you have any suggestions for a particular variation?
Please correct me if I'm wrong in any of my following assumptions...
I've been trying to read up on postural dysfunctions, and in this case I'm inquiring about lordosis and treatment. The course would be to train posterior pelvic tilting through working the rectus abdominis, loosening the hip flexors and activating the glutes.
The first movement that comes to mind for a CFer would be knees to elbows, preferably done strictly with minimal shoulder closing/kipping. However, bringing the legs up from being straight involves the hip flexors. Is this acceptable or would this lead to further hip flexor tightening?
Alternately, one could statically hold the knees up to 90 degrees, thereby eliminating the leg straightening portion and shortening the range of motion. But keeping the legs at 90, whether doing knees to elbows or reverse crunches, doesn't really remove the involvement of hip flexors anyway. Rather it simply replaces isotonic contraction of the hip flexors with isometric. Is this even worth fretting over?
Another alternate movement that comes to mind would be a pelvic tilt/supine glute bridge. It doesn't seem to use the hip flexors. However, it lacks the "intensity" of the other movements and seems more appropriate to simply use a mobility warm up rather than something to include in a metcon circuit.