The workout resembled a Pro Day ... with the QBs throwing passes downfield while receivers ran routes. The quarterbacks even helped each other out.
The ex-49ers signal caller has been broadcasting his training sessions on social media for over a week now ... seemingly showing his arm strength, footwork and overall skillset hasn't deteriorated since he last was on an NFL field in 2016.
Of course, the 34-year-old QB believes he's been blackballed because of his National Anthem protest ... but continues to fight to get back into the league.
Activist Shaun King -- who's been supportive of Kap -- caught a glimpse of his workout today and says it's obvious his athleticism is not the reason why he's not signed.