NORTH READING — You can look at “Batman v Superman: Dawn of Justice” as an epic blockbuster that earned a whopping $181 million in its first four days, or as a disjointed comic-book mashup that earns its mixed reviews over 153 minutes.
But for Walter Norton Jr., the clearest measure of the film’s success unfolds in a sequence that lasts less than 30 seconds. In it, Ben Affleck, as Batman, prepares for his showdown with the Man of Steel with a punishing workout, his shirtless torso ripped and glistening in the dim light of the Bat Cave.
It’s the sum of 20 months of training to make Affleck the biggest, buffest Batman ever. Norton put Affleck through more than 500 workouts, each designed to build and sculpt the actor’s body and ensure that, in those moments on camera, each muscle on his 222-pound frame rippled just right.
“We wanted his body to look like a heavyweight MMA fighter,” Norton said Monday. “Someone who carries a lot of muscle but is able to move.”
Norton sat among the weight-lifting equipment at the Institute of Performance & Fitness , the spacious North Reading facility he owns. “We knew that over a couple of days when the scenes were being filmed, he’d have to peak in a certain way.”
Affleck’s success, Norton said, started with his dedication to workouts that combined a dizzying array of exercises: squats to build leg strength and muscle; vertical and horizontal pulls to add size and strength to his arms and back; vertical and horizontal pushes to thicken his chest, neck, and torso; hybrid exercises to strengthen his core and improve his movement.
The program also required sticking to a diet — customized by nutritionist Rehan Jalali and administered by Affleck’s assistant, Madison Ainley — that featured egg whites and oatmeal, nuts and fruits, lean proteins, vegetables like cauliflower and broccoli, and protein shakes before and after workouts.
Affleck, who also trained with Norton to achieve a defined but much leaner look for the 2010 film “The Town,” acknowledged him as “the best trainer I’ve ever had” on a plaque that hangs in Norton’s office. The actor did not respond to a request for comment.
Another, cheekier sign there reads: “Always be yourself unless you can be Batman. Then you should always be Batman.”
Norton, who grew up in Mattapan and Brookline and graduated from Boston University in 1993 with a bachelor’s degree in Human Movement, has worked more than 20 years as a trainer. He has been the strength and conditioning coach of the Boston Celtics, including the 2007-2008 NBA champion team; the gold-medal-winning 1998 US women’s Olympic hockey team; and the New England Revolution. As of Tuesday, he said, he is working with the Harvard women’s ice hockey team.
He met Affleck when another trainer recommended him to the actor during the filming of the 2010 movie “The Company Men.”
Over the years, Norton traveled wherever the actor was filming for workouts that “would start at 4 a.m. on a regular basis. His consistency is amazing.”
A sure way to set Norton off is to ask him which exercises one needs to do to become Batman.
“You’ve got to develop some pretty damn good habits. You’ve gotta have an attitude where you want to be better than you are right now,” he said. “Because if you’re not getting rest on a regular basis, and you’re not taking care of your body, then chances are after two weeks of training, you’re going to be, like, ‘This sucks, I quit, I’m sore, I’m tired, I’m beat.’ ”
When a reporter asked him to demonstrate the workout that turned Affleck into Batman, the brooding superhero with 8 percent body fat, Norton gave a dismissive chuckle. They’re all “fairly functional exercises that you’d find at any everyday gym,” he said.
To illustrate his point, Norton had Wayne Puglisi, 45, go through some of the exercises in Batman’s on-screen workout. He pushed a sled piled with 180 pounds across a strech of astroturf, which develops leg strength and power. He pulled the sled, which builds core, grip, and torso strength. He did a chin-up with a 45-pound plate chained around his waist.
A Globe reporter tried the same exercises and felt pretty cool when he was able to finish the sled push and pull, and come within a few inches of a chin-up with 45 extra pounds dangling from his belt. Not bad for a 53-year-old guy off the street, right?
But he got some no-nonsense critique from Norton. The reporter’s back needed to be straighter on the sled pulls. He should’ve worn sneakers, not shoes. And he cheated on the chin-up by starting with his arms slightly crooked.
“If you want to pat yourself on the back that’s fine,” Norton remarked. “If you want to do it right, that’s also good.”
To carry off a perfect pull-up in the movie, Affleck did multiple sets of chin-ups and pull-ups in at least 200 of the 500 workouts, using 20 different variations on the exercises so that each and every muscle in his arms and upper body would be worked and defined, without overworking any particular one.
“Sometimes it builds a little more forearm, sometimes it builds a little more shoulder, much more back, more mid-back, more trapezius, depending on what you want — more bicep, more shoulder stability,” Norton said.
The meticulous approach was appropriate for a film with a director, Zack Snyder, who is a fitness enthusiast in his own right, and to play opposite British actor Henry Cavill, whose Web page details ruthless workouts that went into making him a worthy Superman.
“A bunch of these people have really set the bar high in terms of what type of shape you have to be in to be a superhero,” Norton said, citing Chris Hemsworth’s work as Thor and Chris Evans’s portrayal of Captain America, as well as Hugh Jackman as the Wolverine in the X-Men films.
“[Jackman] has 15 shirtless scenes in a movie,” Norton enthused. “That’s an amazing amount.”