That workout was a primary reason why the Redskins signed him, wanting him to compete for the starting job with Rob Kelley and Samaje Perine to be their every-down back. Peterson might be around for only a couple of weeks; he might last a lot longer. It depends on how he looks, as well as on the health of the other backs.
But Peterson is 33 and coming off a season in which he failed to make an impact with New Orleans, then was traded to Arizona. In two games, he was dominant; in his other four games, he was not.
"He's a physical freak," Redskins coach Jay Gruden said. "He's in great shape, explosive, and that's what sold us. Some of the backs we had in here [for workouts] were huffing and puffing, keeling over. He was standing straight up. He could have gone on another two hours."
The big question will be the same as last season for Peterson: What does he have left? Over the past two seasons, he's averaged 3.1 yards per carry, third lowest among backs with at least 150 rushes.
"It shows me people don't really know about football," Peterson said. "People that know the game of football know different situations a player might be in. So when people go back and say, 'Oh, 2.4 yards per carry,' there's a lot that contributes to that as well. I just brush it off."
Peterson has ignored his recent stats and focused on his workouts as proof of what he still has left.
"Every summer, we have young guys that come and work out in our gym, and [no one] has outworked me," Peterson said. "I'm talking about 21-, 22-year-old guys. No matter [if it's] speed work, agility work, running the hill. So that right there is a good measuring stick as well. When you watch the film, I feel like [there's] evidence there to show that, hey, he's still got the burst, acceleration, the power. But I guess everyone doesn't view it that way, and that's fine."
His workout convinced the Redskins they should sign him. Gruden said Peterson barely broke a sweat during a 40-minute workout Monday, in which running backs coach Randy Jordan had him running and going through drills.
"What I saw yesterday was a lot of fuel in the tank," Redskins vice president of player personnel Doug Williams said.
What he has left on the field remains to be seen. Peterson went through his first practice with the Redskins on Tuesday, jogging onto the field wearing No. 26 rather than his customary 28. That number belonged to Pro Football Hall of Famer Darrell Green and remains off limits.
Peterson was fourth in line during individual work, taking his turn after the three running backs who have been around all year: Kelley, Chris Thompson and Kapri Bibbs. But he stood out because of his size; at 6-foot-1, 220 pounds, he's taller and bigger than the others in his group.
During the drills, Peterson showed some of the footwork that will make him a future Hall of Famer. But he's a little rusty. At the end of his rep in a pass protection drill, Jordan reminded him to not overextend his arms while blocking. Another time, after Peterson ran through a gantlet where other backs knocked him with shield pads, Jordan praised Peterson but also told him to maintain his balance.
His new teammates must toggle between admiring what he's done and trying to keep their jobs.
"I was kind of amazed," Kelley said. "Before you become a football player, you're a fan of it, and I have the opportunity to play with Adrian Peterson. It feels surreal. A couple weeks ago at camp, Coach Jordan asked all the running backs, if you could start a franchise with any player, and I picked AP. That's crazy."
Peterson has rushed for 12,276 yards and 99 touchdowns. The other five backs on the roster have rushed for a combined 2,633 yards and 15 touchdowns. But injuries, more than lack of a proven résumé, are what prompted Washington to call Peterson. The Redskins lost rookie Derrius Guice to a torn ACL in the preseason opener. Perine will return soon from an ankle injury, but Byron Marshall (knee) might miss another four weeks.
There's urgency to see what Peterson has left: Gruden said he'd like to play Peterson in Friday's preseason game vs. Denver.
"I'd like to see where he is after contact, want to see the explosion in the hole. His vision. All that good stuff," Gruden said. "I don't think he's going to lose that; it's just a matter of taking hits play after play after play and see where he stands as far as stamina goes.
"You have a good idea of what he's good at based on his career, and we have all those runs he's been successful with. It makes our play-action game a little better ... and your play-action bootleg game a little better. We understand the skill set Adrian has."
Washington worked out Orleans Darkwa on Sunday. Jamaal Charles visited the same day, although he did not work out.
Peterson, though, was happy to do so. Though others teams had called him, they wanted to wait to see how their respective situations unfolded. The Redskins had a need.
Peterson also is close friends with Redskins tackle Trent Williams, a fellow Oklahoma Sooner whom he owns a gym in Houston with.
"I've always talked about playing behind a good offensive line. I know my last couple of years, kind of struggled in that department," Peterson said.
The Redskins were disappointed when Guice was injured. For some, Peterson has provided a pick-me-up.
"He brings big-play potential. Actually, he brings confidence to this team, to this offense," Williams said. "To have a guy who everybody really watched -- if you're familiar with football, you know what he's done. I know myself he's very much still capable of putting up those types of numbers. I've seen it. I've seen him the last two years. This year coming off injury. I know he's ready. I know he's in shape. I'm excited. ... Supremely gifted athlete that works harder than probably anybody I've ever met."
But it has to translate to the field. His first impression was a good one. The Redskins hope it lasts.
"He looked good," Redskins linebacker Mason Foster said. "I know it's practice. I know it's fresh legs or whatever you want to call it, but at the end of the day, it's Adrian Peterson, and he still looked like Adrian Peterson."