For over a decade, since he first picked up the Thor title, Chris Hemsworth’s transformations have been legendary. He’s pushed the limits of his physicality for roles. From Norse god to huntsman, the Australian actor is always training for one well-armed hero to another. Luke Zocchi, his friend and personal trainer, has been beside him through it all, making sure every gym session is elite.

The duo recently wrapped on Extraction 2, a sequel to the hit Netflix action thriller where Hemsworth plays black market mercenary Tyler Rake, and Furiosa, the follow-up to Mad Max: Fury Road. Before that, they were testing the boundaries of human performance for the actor’s new National Geographic series: Limitless with Chris Hemsworth. This makes it somewhere north of 15 productions the pair have done together, and all of those fitness journeys have become the source material for their successful wellness app, Centr.

Men’s Journal spoke with Zocchi to get the inside scoop on Hemsworth’s training process, what it really takes to get Thor’s arms, and what’s available on the Centr app.

Behind the Scenes of Chris Hemsworth’s Most Impressive Transformations

Men’s Journal: First things first: How did you meet Chris Hemsworth?

Luke Zocchi: I first met Chris in primary school when we were both kids, and we hung out until high school. Once we left school, Chris went right into acting and I started amateur boxing. I remember Chris would come down to the gym and watch me box. On occasion, I’d have him join me in the ring and we’d throw some punches. Chris is actually a great boxer, but he never wanted to spar or compete because he knew he had to protect that face. In any case, he was really good hitting the pads and his power was impressive. But clearly his path was always meant to be in front of the camera.

When did you two reconnect?

We met back up after he had just wrapped on Thor 2, over a Christmas holiday trip in Costa Rica. He was pretty big and was trying to slim down for his next movie. We were just going on runs, surfing, and hitting some pads together—and I think that’s where he got the idea to have me train him. A few weeks later, he was getting ready for this movie he’d signed on for, gave me a ring, and said he wanted to do a six-week bootcamp. The very next week I was on a plane headed his way. The camp went really well, and I never went back. That was 11 years and 16 movies ago.

Tell us about this Nat Geo series Limitless.

One of the best parts of getting to work with someone like Chris who’s constantly trying to push his limits is that I’m constantly pushing my own. I feel like we’re always learning new ways to become better both in the gym and outside of it. This show was another way to meet new, interesting minds who understand how our bodies and minds work. One of those people who’s featured on the show is Ross Edgley. The guy is a physical freak and so smart that I’m blown away. I’m glad he’s become a friend.

Some of the episodes focus on strength and physical perseverance. Hemsworth does a 100-foot rope climb. How does one go about training for that?

Ross was a huge resource. While we’re no strangers to training arms, he really wanted to help give Chris what he called “bulletproof biceps.” Since it was a lot of wear on the upper arms, he didn’t want any risk of a biceps tear. For that, we did heavy-weighted chinups, where we had two big plates hanging off the belt while Chris was on the bar. On top of that, we did concentrated curls where he was moving a lot of pounds with dumbbells and the EZ bar.

Testing the effects of cold-water therapy in Norway looks equally challenging.

That was an awesome experience to be out there with Ross, the surfer Mick Fanning, and Dr. Peter Attia. Before the rest of the guys did their swim, I went on an evening dive and thought I was gonna die in that water. The temperature was around 2 degrees Celsius, which is not that far off freezing. My whole body was pins and needles, before going numb. Getting out of the water was even worse. But there is an exhilaration that comes with that feeling, especially when you’re walking through snow on the way in and out.

How does prepping Hemsworth to play mercenary Tyler Rake in the Extraction movies differ from training him for the Marvel movies?

Getting ready for Extraction, we implement a lot of action-specific training. These moves have a lot of stunts, and Chris wants to do as many of them as possible. The fight scenes are done in one shot with no cuts, so he has to be able to keep up these intense strikes for long periods. We joked that Chris’ stunt double Bobby [Holland Hanton] was the highest paid stunt double in the industry for the amount that he had—or, more accurately, didn’t have—to do.

Can you give a little insight into what the workouts look like for the Extraction movies?

There’s still a lot of weight training, but it’s set in more of a circuit style. There are more reps and mobility—like dumbbell complexes that have a lot of range—and not as much CrossFit. In addition to those circuits, we dove back into the fight training as well, practicing boxing and muay Thai regularly. We kept all of that going while we were filming. Before an action scene was going to be filmed, we’d have him practice some animal flows to open him up. Quickly after that, I’d have him hit a few sets of body weight squats and pushups. During the preparation before filming, we were doing those movements for months in between our weighted sessions. I’ve done a qualification for the sort of functional training first responders and Navy SEALs have started to adopt. Each session would be capped with an intense cardio, like an assault bike or a rower finisher to improve his aerobic capacity.

How does Hemsworth bounce back from those intense training sessions and fight sequences?

That’s a huge challenge we face with these movies. Because there are so many physical stunts, we have to put a whole lot of focus on recovery. Following the sessions, I had him going between hot saunas and cold showers—and there was no issue finding the latter because all of the water was freezing in Prague. We’d go out swimming in the water, too, which was great for inflammation. I always had a foam roller and a Theragun on me while we were traveling so that we could loosen up anywhere. The final kicker was we started working with an incredible physio who’d also worked with Rafael Nadal. Having that expertise around to support the recovery we needed allowed us to take everything to the next level without worry.

How does nutrition fit into all of this?

During these movies, we stick to an intermittent fasting schedule, generally on the 16/8 guidance [eating within an 8-hour window and fasting for 16]. The meals would start around 11 in the morning with a shake, then continue until around 7 at night. We do about three to four meals, normal portions with vegetables, carbs, and protein. Chris loves red meat, so generally there’s a steak every two days or so.

Since Extraction 2 wrapped, what are you working on now?

Right now we’re in Australia filming Furiosa, the prequel to the most recent Mad Max movie. The training we were doing led easily into the work for this movie. Like a few of the past movies, there’s a bit of torso on show, so we’re definitely keeping up with the training, but not as intense as Thor or Extraction. The nutrition is about the same as well. The makeup team needs about three hours to get him in costume. We like to joke that it takes them all of those three hours to make him not look incredibly handsome. That works well with our eating schedule, too, because he gets into the makeup chair in the morning, falls back asleep while they apply the prosthetics, then has his first shake with his coffee around 11 in the morning.

Of all the Thor flicks, was prepping for Thor: Love and Thunder the most grueling?

Every time Chris has played Thor, he’s pushed to take the look into that next phase. This last time we absolutely went harder than ever before, and pushed the limits in the gym. It was especially difficult because the filming was done during the pandemic, which meant we had to get him in shape and keep him there for about a year. That is in contrast to the three months it usually takes. Chris has gotten used to suffering in the gym, but one of the hardest parts for him is the amount of eating he has to do. We’re handing him meals every two hours, usually plates of chicken, rice, and broccoli. There’s a particular scene where Thor’s clothes disappear while he’s tied up, and we trained for that moment like he was a bodybuilder. The director gave me a heads up before we filmed it. I had him dehydrated, doing high-rep sessions, and we hit a crazy bodyweight session right before he filmed. The scene took us three or four takes. That’s all it took.

Hemsworth is perhaps most envied for his arms. Any secrets you can divulge for helping to build massive biceps?

People ask me all the time how they can get arms like Chris, and there are some things that I can share, but having his genetics doesn’t hurt. I like to call the top of his arms the “Hemsy horseshoe” because of the shape of them. They’re just crazy. But another key to it is the fact that while we train the whole body during the week, every single day hits arms. That started when we had our first costume fitting for Thor when we were training together, and we saw the arms were the main feature being shown off. I remember Chris turning to me and saying, “We have to hit these arms.”

The work day on set is long, somewhere around 12 hours. I’ll put together a special cart with training equipment that I’ll roll from stage to stage when we’re filming. The cart has a preacher curl bench with an EZ bar, bands, and adjustable dumbbells. This way, Chris is able to get a pump between scenes and make sure those arms are popping. The go-to weight with the dumbbells during those quick pumps are about 25 pounds each, just a little weight to get everything dialed in.

What goes into creating the programs we find on the Centr app?

I’m the head programmer for the app, but there are also programs that Chris developed himself, like the Centr 6. I still remember when he called me to say he had created a workout where you do six rounds of six exercises for six reps. On the app the program goes for six weeks, training six days a week. Everything people see on the app is based on training we do for all of Chris’ projects. For example, the Power routine was created around the routine we did for Thor. We’re always creating new ideas and developing exercises to add to what is already on there.

Check out Limitless with Chris Hemsworth starting November 16th on Disney+.

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