Blac Chyna & Rob Kardashian Getting Sweaty Together

EXCLUSIVE

0125-rob-kardashian-blac-chyna-TMZ-01Rob Kardashian and Blac Chyna have been getting hot and heavy in more ways than one.

Sources close to the unexpected couple tell TMZ, Chyna has been a positive influence on Rob because she's helping him get back in shape.

But don't get it twisted ... we're told they're definitely more than just workout buddies -- the romantic relationship is fairly recent, and things are more playful than serious.

We're told Chyna introduced Rob to her personal trainer about a month ago, and since then they've done several intense workouts together. With and without the trainer, we're guessing.