When Dwayne Johnson was cast in the lead role of DC's Black Adam, he saw it as an opportunity to get into the henchest shape of his career, packing on more muscle than ever before in order to embody the physicality of a larger-than-life superhero. He has described the process as one of the most arduous things he has ever done—and now his strength and conditioning coach Dave Rienzi is offering some insight into the challenging training program that helped Johnson achieve those epic gains, starting with his "3D superhero arms."

"The objective for the build phase was to build just lean muscle," explains Rienzi in a new Instagram video. "We weren't bulking up, we weren't packing on tons of pounds. So that meant bringing the intensity to another level, and these were some of the hardest workouts DJ has ever done."

Rienzi begins the session by targeting the triceps with rope pushdowns. "You're going to want to really squeeze at the bottom of repetition, with 30 seconds of rest between sets," he says. This is followed by dumbbell skull crushers, where he advises extending the arms further back in order to keep that tension on the triceps. He breaks the sets of 12 here into 4 reps with 3-second negatives, 4 with alternating static holds, and 4 regular reps.

Then it's dual cable pushdowns, where Rienzi alternates between an underhand and overhand grip, and dumbbell kickbacks with 2-second holds.

After 90 seconds of rest, Rienzi moves onto biceps, kicking off with barbell curls. "Focus on pausing at the top of each rep," he says. "Starting out of the gate you're going to get a crazy pump." Next up are dumbbell concentration curls, where he performs 4 reps with 3-second negatives, 4 with 3-second holds, and 4 traditional form.

Rienzi ends the workout with a tri-set of incline dumbbell curls, incline hammer curls, EZ bar spider curls: he calls this his favorite part of the session, finishing strong by hitting both the biceps and the triceps.

Here's the full Black Adam arm workout:

• Rope pushdowns (4 x 20)
• Dumbbell skull crushers (4 x 12)
• Dual cable pushdowns (4 x 10)
• Barbell curls (4 x 20)
• Dumbbell concentration curls (4 x 12)
• Tri-set: incline dumbbell curls, incline hammer curls, EZ bar spider curls (4 x 8 of each)