I think that unless you get some with a strap that goes under your foot that’s attached to the bottom of the leggings or modify it to have some, that you will always have that crease because you’re moving around.

Here’s an example https://oldnavy.gap.com/browse/product.do?pid=544598002&vid=1&tid=onpl000102&kwid=1&ap=7&gad_source=1&gclsrc=aw.ds#pdp-page-content

I would imagine this is twofold: fit and material.

• For fit, if the leggings are too tapered at the bottom, and you have a defined or larger calf, the legging will attempt to move to the narrower area above the calf. Alternatively, if they are not tapered enough, and they are below the calf normally, but rising up onto it, you need more taper to keep that from happening. Just dont go so tight you cut off blood flow.
• For material, the amount of spandex plays a big role in fit. Too much, and it will easily stretch around your calf and move, too little and it won’t conform properly. If they are 100% polyester, thickness will play the same role.

What materials and percentages are they?

Disclaimer: I do not wear leggings, but I do wear base layers biking and backpacking, and sew, so I have some limited knowledge here.

Wait.

Like the front?

I have exactly 1 pair of “leggings” and now like 3 pairs of estimated long johns. The former is for exercise, the latter is for warmth but both are equally excellent for general movement.

If you want less crease I’m imagining… possibly stiffer material.

I read this as “legs creasing below the knees”

Drop a tungsten rod from space and have it land on your leggings.

Spray Adhesive

Just wear cutoff jeans to workout instead.

I don’t have solid answer for you; I have no experience with leggings. I have had to put effort into finding pants that fit me appropriately, and that made a big difference in comfort and confidence. Rise was a big part of the equation for that item of clothing, but it related to fit in the groin. Ultimately, the correct rise led to better fit down leg. YMMV. Good luck!