Murderball begins with sobering close-ups of Mark Zupan, quadriplegic and wheelchair rugby warrior, methodically girding himself: In brief interview snippets, he matter-of-factly lays out his condition, how he got this way, and then goes about the business of kicking ass. Other interviewees are treated similarly, and before long you’re in the thick of a bunch of maniacs launching themselves at each other’s wheelchairs, ostensibly trying to gain possession of the ball and score, but seemingly trying to lay as much waste to each other as possible. “Transcends wheelchairs early,” I scribbled down; “it’s a sports movie.” No Triumph Of The Spirit here, just a tribute to the kind of dedication that leads to the impressive sight of a dozen men banging on the sides of their chairs and howling as loud as any football team about to crush the enemy.

But Murderball, despite its many merits, turns out to be unable to focus on any one thing, be it a unique breed of sports obsessive or otherwise. Instead, the movie is stitched together out of dozens of three- or four-minute snippets, flitting back and forth from diverse topics and subjects, never settling on one. It’s a movie without focus, and while it remains consistently engaging, it could’ve stood to settle on just a few people or topics to follow in depth. Instead, we learn about everything from sexual rehab (a video demonstrating just how the newly disabled can engage in intercourse) to the intricacies of US-Canadian paralympic rivalries (which unfold with a degree of intensity appropriate seemingly only to “South Park”), but none of it in detail.

At its best, Murderball is a jock documentary, a refreshingly blunt and macho film for a documentary niche market normally devoted to celebrating only cute children and society’s outsiders. Rubin and Shapiro avoid keeping the wheelchairs in the frame unless they’re making a point. All head-on interviews are from the chest up, and they avoid perfectly the problem of using their quadriplegic status as a crutch for sympathy or excuse for lazy filmmaking. Obviously whittled down from hundreds of hours of footage, Murderball rarely lacks for an appropriate shot. But there’s too much here, not too little.

Take Keith, whom we meet early on as a newly crippled quadriplegic. Bitter and taciturn in rehab, he returns home to dolefully examine the beloved motocross bike that led to his accident. Then Keith simply disappears from the film until the very end, when champion Zupan visits the hospital and gives a recruitment talk for wheelchair rugby. Keith’s eyes light up, he tries Zupan’s chair, and a new jock is born. Later, Zupan mentions Keith in a press conference as an example of the benefits of the sport. End of story. Using Keith as a mere prop for the other characters seems both reductive and plentifully unnecessary: Keith deserved either his own story or nothing at all.

While Murderball has too much in it, it’s never boring. Between the constant, adrenalizing games, there’s a bracing matter-of-factness to the quadriplegics, saving the film from potential bathos at every time. Shapiro and Rubin attempt a few ill-advised poetic touches (animating one player’s dream of flying over the moon, able-bodied), but it doesn’t suit them. Their métier—and the players’—is action. Which makes the finale even more frustrating: After spending a whole movie skirting Triumph Of The Spirit clichés, Shapiro and Rubin show the climactic game in sentimental slow-mo, complete with the Polyphonic Spree on the soundtrack. (They do better when sticking with the grimly pulverizing tunes of Ministry.) Up until that point, though, Murderball is a consistently entertaining—if too schizoid—look at a fascinating subculture.

—Vadim Rizov