my sis is that big, maybe a lil bigger, and she just wears a good supportive sports bra with thick straps. looks proper ugly but stops her getting two black eyes. she does trampolining.
I got a fairly good sports bra (34F) from marks and sparks and i don't jiggle too much in that. I want to get a high impact one as well though.
this is a crap answer but i find wearing a tight sports bra a couple sizes too small made of STRONG stuff with THICK straps holds it all up. or a size smaller moulded cup bra, non low cut- eliminated jiggles
A bra that's size smaller makes you sweaty and won't be comfortable. A normal bra just won't do it either, just because you can't see much jiggle doesn't mean you are being fully supported so you can still end up sagging.