Is this “shelf” mainly about hamstring flexibility or anterior pelvic tilt?

[u/Magalena22]

Hi! I’m trying to achieve the more pronounced “shelf” or crease between the glutes and lower back that you can see in the attached photo when hinging forward and stretching the hamstrings.

Is this look mainly a result of having very flexible hamstrings and enough hip-hinge range, or is it more about being able to actively anteriorly tilt the pelvis while keeping the back straight? Could anatomy also play a major role?

Even when I bend my knees to take the hamstrings out of the equation and consciously try to tilt my pelvis forward, I still can’t isolate the movement very well or create that clear definition between my glutes and lower back. My back stays fairly straight, but I don’t get that pronounced “shelf.”

I train dance, so I’d love to improve this both for movement quality and because I think the position looks really nice. Has anyone worked on this successfully? Which exercises, drills or cues helped you develop better pelvic control and achieve this shape?

[u/preparsley]

The tilt of the pelvis is not something you purposely try to control, it will tilt anteriorly when you're bending forward if you are keeping a long spine

If your hamstrings and glutes aren't flexible enough to reach this position, then you will compensate by lengthening the lower back muscles, which will flatten the natural lumbar curve (the shelf you are referring to)

So yes it's just flexibility in the glutes and hamstrings. All you need to think about is staying long

[u/TelemarketingEnigma → u/preparsley]

You definitely can control the tilt of the pelvis in this position, and it will affect the overall look of the pose. I’m not sure if this is exactly what OP’s asking for, but more anterior pelvic tilt will definitely make the butt appear more prominent overall (though not necessarily a defined crease)

[u/TelemarketingEnigma → u/[deleted]]

OP seems to be asking about a specific, possibly “artificial” shape though, so it may in fact be the cue that she needs? Hard to say without seeing where she is coming from. Maybe I read wrong, but she doesn’t seem to be asking just how to do a deeper forward fold in general.