Cardinals Superstar David Johnson Squats 495 Pounds Three Times!!

Cardinals superstar David Johnson's out to prove he's back ... and he's doing so by throwing nearly half a thousand pounds ON his back!

The stud RB put 495 pounds on the barbell Wednesday and squatted it ... THREE TIMES!!

FYI -- Johnson missed 15 games last season 'cause of a wrist injury he suffered in Week 1 ... but, clearly, dude's no worse for wear heading into this season.

We know what you're thinking ... not THAT impressed, especially since Rams star Aaron Donald just BENCHED that last month.

But, you should be ... D.J. only weighs 224 pounds -- so it's more than DOUBLE his bodyweight!!