After all, a 50yo men can exterminate all groups (flyerfiles, boston guys, cannibal, predators and cie..). and it's natural.It's not natural. And I doubt Abby has access to the drugs given its an apocalypse.
Even if it were a male I'd say it was steroids. You can see her muscles are showing even without flexing. Not natural for muscles.
But a woman body stereoids... it's fucking non sense apocalypse