James Harrison is the KING of crazy strength training videos ... but an NFL rookie might be comin' for the throne.
In the blue corner ... 39-year-old Steelers LB pushing a sled weighing OVER 1,800 POUNDS -- that's one plate for each year of his life.
In the red corner ... 22-year-old Falcons LB Duke Riley pulling an SUV weighing AT LEAST 5,500 POUNDS -- a 2017 Yukon Denali plus his buddy in the driver's seat.
James takes a few tries. Duke did his easy.
Keep in mind, though ... pushing is harder than pulling -- and Duke has wheels workin' for him too.
So, what's more impressive?