Lindsey Vonn Does Broken Arm Pull Ups

Talk about determination ...

Lindsey Vonn broke her arm just over 2 weeks ago ... and she's already back in the gym working out like the freak athlete she is.

Vonn fractured her humerus while training in Copper, Colorado ... but it's hard to tell in the video she just posted on Instagram.

The world-class skier provided an update Wednesday, proving that she's not gonna let a broken arm keep her from getting in a few pull ups.