The center of mass isn't really meant to "lead" the body; it's meant more for poses where you want to change the balance. If your figure is carrying a large object in its left hand, you might be able to shift the center left or right to make the abdomen and hip look natural. I haven't used it; found it easier to just manuall adjust things until they look right. For sure the BVH file doesn't include the center at all. I just tried exporting a BVH from Poser 6. It includes a couple of odd entries for FaceActor, but not the Center.

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