The laws of moviedom decree, of course, that Mark will soon lose, and his well-earned sense of invincibility will shatter. The Smashing Machine bounces between Mark’s home and Japan, where the Pride Fighting Championship takes place. That’s where Mark, a much-celebrated champion, is taken down by an illegal but nevertheless humbling move. After the fact, the match is ruled a tie, but the stink of defeat never dissipates.

The real battle, in any case, is at home. Mark’s dependence on opioids for the punishing extremes he endures is becoming desperate. The Smashing Machine is based on John Hyams’s 2002 documentary of the same name, and part of the nature of that film was the curiosity of Mark’s extreme violence in the ring and his otherwise sweet passivity. In Safdie’s film, Mark is asked in the doctor’s waiting room if fighters hate each other during a bout. “Absolutely not,” he replies.

But while we don’t doubt Mark’s sincerity — he’s as earnest as he is muscle-bound — Johnson also exudes an inner turmoil, and a struggle to keep his rage at bay while nursing mounting wounds to his ego. His body is so stiff, it’s like he could snap at any moment.

That’s the case for Mark, most of all, around his wife, Dawn Staples (Emily Blunt), a former Playboy model who’s shown as alternatively supportive and insensitive to Mark’s situation. They feud often, sometimes immediately before a match, sometimes over how to make his shakes. When he tries to give up opioids, he takes her late-night drinking as a provocation. “Treat me like a man,” he tells her.

It’s an awkward, perhaps judgmental characterization that would be all the more glaring if it weren’t for Blunt’s tact as a performer. But it throws The Smashing Machine off course, especially when the movie seems to want to lean more on its other central relationship: that of Mark and his friend, trainer and sometimes competitor Mark Coleman (played by former Bellator champion Ryan Bader).