James Harrison does pushups with a 300-pound man on his back

(AP)

Mere weights are no match for James Harrison in the gym. No, James Harrison requires 300-pound men to sit on his back to do pushups if ever hopes to break a sweat.

Behold ...

That's 36-year-old Steelers linebacker James Harrison doing pushups with 6-foot-4, 304-pound center Maurkice Pouncey on his back like it's nothing. You can watch the NSFW video here.

It's impressive, and a good reminder that linebackers in the NFL are impossibly strong regardless of age. It's also a good reminder that NFL drug tests are totally random and if James Harrison happens to get tested tomorrow it has nothing to do with the fact that he just finished doing pushups with a 304-pound mammoth of a man on his back.