This is what it takes to be Batman: pushing a sled loaded with circular 45-pound weights (one guy moves 180 pounds) across 30 feet of indoor Astroturf, while trainer Walter Norton, Jr., watches and barks advice and encouragement:

“Chin down. Every time you pick your chin up, your hips go up.”

“Knees up, knees up. Higher, higher!”

“Good! Keep your chest up, keep your head up, look out. Don’t look down.”

Norton (SED’93), owner of the Institute of Performance and Fitness, a coaching gym 25 minutes north of Boston, put Ben Affleck through this exercise and many others during 500 workout sessions intended to buff him up to play Batman for Batman v Superman: Dawn of Justice. Norton crafted a regimen of weights and squats and pushes and pulls and more that put Affleck through hell.

That’s a deskbound writer’s description, not Affleck’s. He certainly knew what he was in for—the film was their 10th project together.

“Walter is great,” Affleck says. “He’s focused, disciplined, and dedicated.” Norton’s office wall boasts a plaque showing the actor doing a chin-up, with an inscription to “the best trainer I’ve ever had.”

In Detroit, where parts of Batman were shot, Norton would put his famous client through his paces five to seven days in a row, then take two or three days to tend to his clients back home. Henry Cavil, the film’s Superman, used his own trainer.

After six years of travel to locations with Affleck (and a few Caribbean vacations together), Batman will be Norton’s last movie for now. His wife is assistant coach of Harvard’s women’s ice hockey team, and he recently got a gig training the players. He says that given his new job and his gym responsibilities, “I said to Affleck, ‘It’s been amazing, I really appreciate it, but we’re done.’…As much as I like Ben, I like my wife more.”

The two started working together when another trainer recommended him to the actor, and they hit it off. “He went to Cambridge Rindge and Latin School,” says Norton. “I went to Brookline High. We knew a lot of people in common.…We had a lot of the same interests,” including devotion to craft, a trait he discovered in Affleck while working on their first movie together, The Company Man. Other films that Norton trained the actor for include The Town, Argo, Gone Girl, and Live by Night (to be released next year).

A stickler for hard work and punctuality, he credits his late, revered BU professor, John Cheffers, for teaching him to plan ahead. “If you’re into your craft, you don’t show up looking the same way for every movie, unless you’re choosing the same type of role,” he says. “So the Rock [professional wrestler Dwayne Johnson] looks a certain way because he’s taking mostly the same roles all the time.…Ben takes his craft really seriously, so he wanted to have a different look for every movie.”

Norton sculpted Affleck for films the way Alexandros of Antioch crafted the Venus de Milo. He got the six-foot-four actor to 222 pounds to portray the massively muscled Dark Knight. By contrast, in 2010’s The Town, where Affleck played a member of a Boston holdup gang, he needed a leaner, less Hulkish look; Norton made him 198 pounds for that film.

For his turn as the Caped Crusader, Affleck needed a bulkier build than Norton helped him achieve in other films. Photo courtesy of Flickr contributor tricks ware

Celtics, Revolution, Olympics, and high schoolers

Norton has owned his gym for about a decade. Before that, his post-BU career included a stint playing pro football in Europe (he’d played at BU) and then one as a football agent in Boston. He has worked for Boston pro teams—as a strength and conditioning coach for basketball’s Celtics and soccer’s Revolution—and also for the US women’s hockey team at the 1998 Olympics, where the team took home the gold medal. But you needn’t be a cinematic superhero or a pro athlete to get Norton’s services.

“I’m rooting as much for the kid without any talent or skill as I am for someone who’s on the high end and extremely good,” he says. Unheralded clients at his gym can be just as devoted to their workouts as millionaire actors and athletes. Earlier in the day, he says, during his college-and-high-school athlete workout, two college students had vomited from the intensity of their exercises. To make the gym more welcoming, he lets his dogs, Lycan, a German shepherd, and Abe, a pit bull mix, roam the floors. This Terrier is a dog lover—when they lick his face, he licks back, and a flier on the door advertises $50 hoodies for sale, with proceeds donated to the state SPCA. (Norton says the gym has given close to $30,000 in recent years to the organization, from which he adopted Abe.)

Norton has the physique to play Batman himself. At six-foot-three and 211 pounds, his chest and biceps swell his T-shirt and its sleeves. Yet his own workouts aren’t always as regimented as the Caped Crusader’s. “Last week, I probably could work out only three times, because it was an incredibly busy week,” he says. “One day, it was less than 30 minutes. Another day, it was 45 minutes. Another day, it was an hour and a half.…A normal week, maybe I’ll work out four times,” 90 minutes per session. He favors strength training over pure cardio exercises, as the former raises the heart rate while also retarding the normal atrophying of muscle and bone mass that accompanies aging.

“I’m in the requisite amount of shape,” he says. “A trainer doesn’t have to be in perfect shape. But”—like an actor playing Batman—“they should look the part.”