Plaxico Burress -- I'm Still In Shape ... and READY TO PLAY

He racked up 45 catches and 8 TDs last year ... but instead of being in an NFL locker room, Plaxico Burress spent his Monday shopping on Madison Ave. in NYC.

Plaxico -- who's only 35 years old -- still has not been signed to an NFL team ... but when we ran into him on the streets of New York yesterday, he assured us he's still in shape and ready to get on the field.

Of course, Plaxico's off-the-field history may have something to do with the lack of interest from NFL teams -- in case you forgot, he accidentally shot himself in the leg at a nightclub a few years ago.

Still, the guy caught 8 FRIGGIN' TOUCHDOWNS last year.

So, we gotta ask ...