http://www.npr.org/blogs/health/2011...nx?sc=fb&cc=fp
we-e-e-ll...
They're talking about spanx, which end at the hip joint, worn for cosmetic reasons. I've never worn them, but it seems obvious to anyone who's ever worn too-tight underwear that they would put pressure on the soft tissues surrounding the joint, including the nerves.
Totally different animal from graduated compression tights, that start with firm compression in the lower calves and lessen the compression as you go up the leg, ending with zero or minimal compression in the abdominal area, to aid venous return. Remember those were durable medical devices first, prescribed by doctors to post-surgical patients and others who are prone to DVTs or varicosities, and only recently popular among athletes.
And anyone who's worn control-top pantyhose knows they mess with your gut.