In Melvin Gordon, Adrian Peterson has found a challenger and a protege

Peterson training with young bull Gordon (1:09)

Vikings RB Adrian Peterson is getting a push from Chargers RB Melvin Gordon as they take part in offseason workouts together. (1:09)

HOUSTON -- The sprint workouts James Cooper oversees each summer have long been the province of Adrian Peterson. Few have the physical skills of Cooper's star pupil, and Peterson's talents are kindled by a competitive zeal that leads him to regard second place, even in a summer sprint workout, as an affront.

This summer, though, if only for a fleeting moment, Cooper has seen a hint of change. The running back who grew up following Peterson's career, who wears No. 28 because of his admiration for the Minnesota Vikings running back, is edging him.

As Peterson prepares for his 10th NFL season, he's coming off his third rushing title in large part because of the unyielding work ethic that still has him training for three to four hours a day at his gym in Houston. He's working to stay ahead of a young generation of running backs who were raised on Peterson highlights. And in the case of Melvin Gordon -- the San Diego Chargers back who finished second in the 2014 Heisman Trophy voting and was selected 15th in last year's draft -- Peterson has a protege who has come to Houston this summer in the hopes of adopting some of the four-time All-Pro's tenacity.

"It's been really intense -- I'm not going to lie to you -- with everything we do, from the warm-up to the finish," Gordon said. "If you know Adrian, you know everything he does is balls to the wall. Everyone's trying to compete with him. He's out here, he's going his hardest with everything, and Coop's on him, just like he's on everyone else. It's been intense, but it's good for us."

Gordon, who ran for 641 yards, fumbled six times and missed two games because of a microfracture in his left knee during a trying rookie season. He contacted Peterson in February about training with him this offseason, and in Cooper, he's also working with the trainer who orchestrated Peterson's return from a torn ACL in 2012. Cooper has put Gordon through some of the same drills, designed to improve his balance and proprioception after his injury. Like Gordon, Peterson is coming off a spate of fumbles in 2015. Before the running backs part ways to leave for training camp next week, Cooper will likely put them through 10 rounds of a drill where he tries to punch a football out of their hands with boxing gloves, while they run against a cable loaded with 430 pounds of tension.

The two backs seem to have formed a bond, particularly while sprinting against one another at Houston's Reagan High School. It's in those workouts, Cooper said, where Peterson's drive remains enough to surpass Gordon's edge in speed.

"Adrian probably doesn't want to hear this, but yes, Melvin is faster," Cooper said. "But he's only faster right now in those three or four reps, and then Adrian is there -- I believe that's what Melvin is learning. That's kind of how he's being sharpened. And Adrian is being sharpened by not only this young guy, but, 'Yes, he's faster, so I've got to really show him.' Adrian can beat him in a 400 or 300 or 200, but it's right around 70, 60 meters and under where Melvin can get him.

"When it's just flat out, over a workout, every workout of the day, Adrian will beat him."

Cooper changes his focus with Peterson each year, and this year's emphasis has been on the ability to recover quickly and sustain speed late into workouts -- to emulate carries in the fourth quarter of a game. The trainer wanted Peterson -- and by extension, Gordon -- to be able to run 10 40-yard dashes, no slower than 4.5 to 4.55 seconds, with just 30 seconds of rest between each. The running backs hadn't reached that threshold as of last week, Cooper said, but "we're getting there.

"Melvin is great, (in) one, two, maybe the third rep, but after that, he starts to fall off. He doesn't understand. And that's when 'Prince of Persia,' as I call him, Adrian, he comes in in rare form. (Melvin) is only nudging him out in the beginning, but they're both working hard. It's good to see."

The quip about Peterson -- in reference to his opulent 30th birthday party, where the running back made his entrance atop a camel -- is a hallmark of Cooper's style, one of his ways of reminding the former NFL MVP that he hasn't earned the right to relax yet. Gordon gets the same treatment, and when he contacted Peterson about joining him, he was met with no illusions about what he had signed up for.

"He told me it'd be tough, but I told him that's what I was looking for," Gordon said. "He didn't sugarcoat anything. He told me exactly what it was -- 'You're going to be tired, we're going to push you, you're going to be exhausted after you get done.' ... I was like, 'Man, I'm up for the challenge. I need a great season.'"

The 23-year-old plans to return to Houston after the 2016 season. He's found a mentor who isn't stingy with advice -- Peterson talked about how he has shared tips with Gordon on the back-cut move he has used to fashion many of his longest runs. And he has learned from a training partner who has been able to prolong his career by refusing to relent with age.

The young challenger in his midst has brought something out of Peterson, too.

"He helps me stay on top of my game, as well," Peterson said. "I'm able to continue to push myself along the way. Having him here, it's been good. You always want competition during the offseason.

"It makes me feel good. It doesn't make me feel old at all. But it does put things in perspective, to show the life cycle [of the position] -- these young guys -- 21 years old -- and here I am [at] 31. It makes me feel good to know I have set a bar and a standard. These guys recognize it, and they're putting their best foot forward to get past that. That's what it's all about: motivating these youngsters to do better than you did."