David Corenswet put on a lot of muscle to play Superman, which makes sense when your job description includes lifting buildings and looking believable in a pretty tight blue supersuit. After watching him fill out the cape in James Gunn’s take on the character, I assumed there probably wasn’t much physically the guy couldn’t handle. Turns out I was giving Superman way too much credit in one department: running.
While discussing training for his upcoming football movie Mr. Irrelevant, Corenswet admitted that all the work he did to become the Man of Steel didn’t prepare him for the sprinting required to play an NFL running back. The actor broke down the difference during a red carpet interview with People, which the outlet shared in an Instagram Reel. He had a head start after recently bulking up for Big Blue, so the strict diet and heavy training were familiar territory. Football-specific conditioning, however, was a whole different beast. As he explained:
The familiar part was just putting on a lot of weight. I had just done that for Superman and so I knew a basic plan on how to make that happen. The new parts were the functional training, the running. Superman doesn’t do too much running and Tuggle did a lot of running…
Superman may be faster than a speeding bullet, more powerful than a locomotive, and able to leap tall buildings in a single bound, but don’t you dare ask him to run wind sprints. We may have discovered Kryptonite No. 2.
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According to the Twisters actor, the training had a considerable toll on his body. He continued:
I dealt with shin splints all through production because I hadn’t sprinted in, you know, a decade… It all came together really with the mustache and the hair and then Tuggle’s very charming dialect, which I picked up on.
Honestly, I can’t blame the guy for not being up on his running, as the whole thing sounds miserable. Shin splints? No, thank you. But it also makes sense, given how different the physical demands were. His preparation for a new DC movie centered heavily on gaining size and strength. For Mr. Irrelevant, he needed to move like an NFL running back.
That meant considerably more time actually running instead of pretending to fly. Mr. Irrelevant, which has already seen some strong test screenings, tells the true story of John Tuggle, who earned the slightly brutal nickname after becoming the final player selected in the 1983 NFL Draft. The New York Giants picked him at No. 335, and Tuggle made the roster and became an important special teams player before cancer cut his career short. He died in 1986 at just 25 years old.
The movie stars Corenswet opposite Isabel May, with Michael Shannon playing Giants coach Bill Parcells and David Krumholtz portraying Julius “Whitey” Horai. Jonathan Levine directs from a screenplay by Nick Santora. The actor’s Superman physique didn’t go to waste. The first images from Mr. Irrelevant showed him looking very much like someone who could survive an NFL training camp. But playing Tuggle required a different kind of athleticism than filling out the red trunks, and I kind of love that running was what humbled him.
It is also funny to realize the Pearl actor spent all that time making Superman look superhuman without necessarily needing elite endurance. Why would Clark run five miles when he can simply float there?
Fans can see whether all those sprints and shin splints paid off when Mr. Irrelevant hits the 2026 movie calendar on Dec. 25. Corenswet will then trade the football pads back for the cape when he returns as Clark Kent in Man of Tomorrow, currently scheduled for July 9, 2027.