Dwayne Johnson has probably never heard the words “you need to get bigger” in his professional career. But in preparation for playing real-life MMA fighter Mark Kerr in The Smashing Machine, Johnson got that exact note from the film’s director Benny Safdie. In a career-defining role as Kerr, the blockbuster movie star beefed up to a never-before-seen size in all the years as an actor, or even during his WWE days. And it’s been worth it. Critics and audiences have praised Johnson’s turn as Kerr for both taking on the fighter’s physicality and deftly tackling his emotional journey outside of the ring.
For The Smashing Machine, Johnson partnered with his long-time trainer Dave Rienzi, who had around six months to get him film-ready and prep Johnson to fight during WrestleMania. Rienzi, an IFBB Pro bodybuilder and founder of Rienzi Strength & Conditioning in Sunrise, Florida, has helped Johnson get fit for other films such as Black Adam and the Fast and Furious franchise. But The Smashing Machine required Johnson to put on as much muscle mass as humanly possible to emulate the physique of a two-time UFC Heavyweight Tournament Champion. Training for the role required studying Kerr’s well-documented time in the public eye so that Rienzi could mold Johnson in his image. At the same time Rienzi was careful to keep Johnson injury-free amid all the fight scenes. The result: a near mirror image of the former MMA star.
Rienzi, who affectionately refers to Johnson as “DJ,” spoke with GQ about his training to transform him into his “hulking size,” his high-protein diet, and the one thing that audiences still don’t give him enough credit for.
GQ: When did you first start training with Dwayne?
Dave Rienzi: That was back in 2012. My wife, who’s also his business partner and production partner [and ex-wife], was managing his career at the time. She was looking for someone who had a background in science and an expertise in body building and nutrition. We just hit it off from the start. When I first met DJ, we were chopping it up about training, and I think we both share the same love for training and bodybuilding. I believe the first prep we did together was for WrestleMania that year.
So when Dwayne came to you saying he was going to work on The Smashing Machine, which is based on the real-life MMA fighter Mark Kerr, did he give you any guidance on what he or director Benny Safdie wanted?
When the opportunity popped up, he and I connected and started studying old tapes of Mark to just understand [how] Mark looked—how he moved in the ring. DJ and I identified some key points that we were going to start working on to emulate Marks’ physique. So we had a bunch of things in mind, and then Benny comes in, and we’ve never heard this ever from any director, but he’s like: “Dwayne, I need you to get bigger.” [Laughs.] We were already planning on gaining muscle and getting bigger for the role, but Benny really wanted us to dial it up even more. And at the same time, Dwayne was preparing for WrestleMania. Prior to filming, we had probably five to six months to mold him into Mark. It’s interesting. A lot of times we’re doing training, like for Black Adam, we were molding him into a superhero. But this was different, because Mark is a real person. Mark obviously had a lot of muscle back in his day and really distinct characteristics to his physique that we wanted to really work on and bring to life. Mark had these massive traps and really developed, round shoulders. So it was a matter of putting on the mass to match Mark’s, and also developing the areas that we could attain the silhouette of Mark Kerr so when DJ’s clothed in a shirt, you can see that trap development. You can see those shoulders. Then with the prosthetics and the wig, you’re like “Oh, it’s Mark Kerr.”
Yeah, those traps and delts were pretty epic. What moves were you giving DJ to hit those specific target areas?
We definitely added way more volume than we’ve ever done in the past. So we had our traditional push, pull, leg rotation, but we added in a separate shoulder day to get even more volume on the shoulders. And then we were layering in shrugs like two to three times a week with dumbbells and the trap bar. I’m pretty sure DJ was throwing more shrugs in there on top of it just to keep developing those thick shoulders. You know, we hadn’t done shrugs in years. We shied away from them because when you’re talking about shoulder health, when your upper traps are often too developed, it starts to affect the dynamics of your shoulders. I know DJ was having a really fun time packing on that size and seeing that Mark Kerr physique evolve. I was on set for the entire seven or eight weeks that they were shooting in Vancouver, and he had so many fight sequences that he had to do. The first training sequence we did in the gym, where he was shirtless weightlifting, Bas Rutten [Mark Kerr’s coach during the filming of the documentary The Smashing Machine: The Life and Times of Extreme Fighter Mark Kerr for which the film is based on] was on set too. This was Bas’ first time seeing DJ without his shirt, and I remember DJ’s doing curls or upright rows or something like that and Bas was like “Oh my god, there it is. He’s Kerr.” He was blown away by the transformation and how much DJ embodied Mark. That for me was the highest compliment. If his old trainer is like “He’s Mark,” you know we did it right.
As you mentioned, you were trying to put as much muscle mass on him as you could. How did you balance that with also ensuring he had good mobility and endurance?
That was another key thing: packing on that size and making sure Dwayne still had that explosiveness. Mark was very explosive in the ring. He was powerful with lots of fast-twitch muscle fibers. So it was a balance of layering certain movements or various tempos of movements so that DJ could have that explosiveness. We did lots of posterior chain work as well, so the glutes, hamstrings, lower back. And the other piece too of it all was that he was training for WrestleMania, so he was doing ring work for WrestleMania and then he was doing ring work for MMA training with Greg [Rementer, supervising stunt coordinator]. It was structured in a manner that as he was gaining muscle, he was using his body explosively in the training for the film, so it all really came together nicely where we didn’t lose any sort of mobility or speed as DJ packed on that size.
How does ring training for WWE differ from ring training for MMA?
The MMA stuff is a lot more on the ground. That would probably be the largest difference. MMA is a lot more on the ground, a lot more jiu jitsu-type of stuff. I would say the MMA training was definitely more intense for sure. In WWE, you don’t want to get beat up or injured. I think because DJ worked with so many top-tier MMA stunt doubles and stunt coordinators, he got a lot of different training in various mixed martial arts. So it was definitely a learning experience for him. But I think his background in wrestling really helped him in the film, like for those fight scenes, because he knows how to pull back on a punch to make it look realistic. He knows how to take punches to make it look realistic. Once they were filming and they weren’t getting the shot. The guy was supposed to hit DJ with a certain punch and it just was not looking right. So it got to the point where DJ was like “Listen, man, I need you to hit me on the chin. Let me take this punch. Actually punch me.” And he did, and they got the shot. That’s just DJ’s level of commitment to the film.
Were there any injuries he had sustained during training or shooting where you had to work around it so he could continue to train?
I will say filming was intense. We had probably 18 different days where we were filming fight sequences, so there’s wear and tear on the body just from all of that. And even though you have stunt coordinators, you’re going to get hit here and there. It’s still putting your body in awkward positions. So I would say he was definitely feeling a little beat up towards the end of filming. But another piece of getting Dwayne into shape was on the nutrition side. That’s why I was there for the entirety of the filming because there was a lot of nuance in tweaking and adjusting his training and his diet based on the physical toll he was experiencing. So recognizing how depleted his body was getting while maintaining his muscle mass required a lot of eating. He was having six to seven whole food meals, one shake a day. It was high protein and high carbohydrates. What we didn’t want to do was dirty bulking because it just inherently leads to excess weight gain that you don’t want and a sort of sloppy look that just doesn’t look right. He was eating more than he’s ever done for a film.
What else did you do to help him gain mass?
In addition to eating, we were definitely pushing more intensity with the training: pushing heavier weights, layering up on volume. We had a full posterior chain-focused day we would do during the week. We typically wouldn’t do that, because I would usually include that in his regular leg training, so this took it to a whole other level. Obviously lots of volume on the shoulders. We kept his traditional leg day on the weekends because that’s one of his favorite things: training legs heavy on the weekends. He would send me pictures on a weekly basis, so I could adjust and tweak the training program based on the progress I was seeing. Another piece too was cardiovascular endurance because you can’t perform like Mark without it. We did cardio, fasted in the morning, and we could incorporate high-intensity intervals to really get that heart elevated. And then we’d run like every other day or four times a week.
Were there any rest days?
He would take Saturdays off after the week of filming, just to have nice recovery, so those days he would really just take it easy. Maybe do a little light cardio, some stretching, some foam rolling. He loves to train. I would say his back has always been a really strong point. So we hit every muscle group twice a week, with the exception of back, where we would just hit that once a week, and that allowed us to put all that extra volume and intentionality onto, again, bringing in those Mark Kerr shoulders and traps, while also adding muscle mass to the legs, chest, and upper body.
