The Hills star hit the gym in Los Angeles but, despite working up a sweat, still emerged looking fresh-faced and relaxed.
Audrina was wearing an eye-catching yellow baggy tee which she teamed with a fluorescent pink sports bra and mid-length black leggings.
She kept her long brunette hair swept into a low ponytail and headed to her car in flip-flops while carrying a small quilted Chanel bag on her shoulder.
Referencing her Pilates instructor, Audrina later tweeted: "Another amazing workout today with the one and only Maria."
In the US, MTV are currently airing re-runs of The Hills. Audrina, however, seems to have a slightly hazy memory when it comes to the actual episodes!
She also told fans: "Getting so many comments about The Hills....I forget half of the stuff that Aired!!...There was way more going on behind the scenes!!"