GYM JONES WAS CONCEIVED in a windowless room in a decommissioned bread factory in downtown Salt Lake. The name was bestowed by Twight's wife, Lisa, a martial-arts student who sometimes carries knives hidden in her boots and who told me wryly that she has "a knack for marketing." Mostly, Twight used the space to train friends and himself. He was still climbing hard enough that he wanted a dedicated space in which to keep in shape, and mainstream facilities didn't cut it.

"We wanted to do stuff they wouldn't put up with," he says. "Throwing medicine balls, dropping weights on the ground, working genuinely hard, and creating something with our own spirit, especially the music."

Ah, yes, the music. Few things had fueled Twight's angst-ridden ride as a climber more than punk rock's Sturm und Drang: Sisters of Mercy, the Damned, Skinny Puppy, and a trove of others, spliced together on mix tapes that he blasted into his ears while hacking up some heinous frozen cliff. His 2001 collection of climbing essays, Kiss or Kill: Confessions of a Serial Climber, contains stories with titles cribbed from song lyrics, like "Glitter and Despair" and "House of Pain." Twight's worldview could be so nihilistic that one friend nicknamed him Dr. Doom.

Twight made money in various ways—from sponsorships, from training elite soldiers in alpine fitness and survival techniques, and from serving as a distributor for Grivel, an Italian climbing-gear company. His interest in starting his own gym evolved in part from experiences he'd had with a then-fledgling program called CrossFit, developed by Greg Glassman, now 52, a charismatic former gymnast from Santa Cruz, California, whom everyone simply called Coach.

CrossFit emphasized old-school exercises and movements like squatting, jumping, pulling, pushing, and so on. Glassman had a gym in Santa Cruz but mainly shopped his product through daily workouts posted on crossfit.com, the Web site he launched in 2001. He contended that CrossFit was all most athletes really needed, because it had the remarkable ability to develop strength and endurance simultaneously. It relied on weight-loaded drills combined with "natural movements" performed with grueling intensity. The circuits were christened with colorful names, like Fight Gone Bad, or after Navy SEAL CrossFitters killed in action. Glassman even created a mascot, Pukie the Clown, a Bozo-like character with a cascade of vomit flowing from his mouth.

Twight first tried CrossFit in December 2003, when Glassman invited him to Santa Cruz to attend a certification seminar. He was plenty fit—he could run up 2,000 vertical feet in 45 minutes—but not compared with other workshop participants. They competed against each other in Fight Gone Bad—a three-lap, five-station circuit involving rowing, dead lifts, box jumps, overhead dumbbell presses, and medicine-ball throwing—and Twight finished dead last. "There wasn't enough oxygen in the state of California for me," he said.

Both humiliated and fired up, Twight flung himself into a CrossFit regimen for the next four months, then tested its effectiveness at a Utah ski-mountaineering race called the Powder Keg. He finished in a satisfying 11th place, against a tough field of experts. Convinced that Glassman's style of training was a genuine secret weapon, he became a CrossFit "affiliate"—not exactly a franchisee but a booster for the CrossFit mantra.

After a couple of years, however, Twight says he began to grow disillusioned with the program. CrossFit thrived on a regimen of unstructured daily workouts, but Twight discovered that, while this bolstered his overall fitness foundation, it came at a cost in terms of sport-specific performance. Twight soon found that his power output had increased in certain arenas but his long-range endurance had faltered. He noticed the same thing surfacing among his athletes.

"In December 2006, I gave a test to guys who were training with me that I thought was indicative of their progress," Twight says. "They underperformed to a degree that made me say, OK, everybody's benched for two weeks. I'm gonna go home and figure this out. That's when I realized that we weren't making progress because we weren't planning our training to make progress." CrossFit, he said, conditioned people for CrossFit. "But the gym is not our sport," he says. "Everyone here trains for something else."

Twight recommitted himself to the concept of periodization—modulating volume and intensity over the course of multi-month training cycles. "The biggest disappointment with CrossFit came from treating training as competition (stopwatch, posting comments, etc.)," he wrote to me later. "Our intensity declined, form degraded, and our attitude turned negative as shit got hard, because the training was not designed to support athletic performance outside of the gym. Now we build in recovery periods to assure proper intensity and form. We insist on progressively harder intervals (the last should be the fastest). We don't train to failure. We mimic work/rest intervals common to the sport-specific task."

Twight still relied on CrossFit-style circuits for the foundation-building phase of his training, and when videos of his work on 300 emerged, showing the actors performing the familiar circuits, Coach blew a gasket. Not only had Twight split from the tribe; he was cashing in on his newfound knowledge. Commercially, CrossFit was doing much better than Gym Jones. (It's on track to earn more than $13 million this year. Twight, whose operations remain private, earns roughly $200,000 a year with Gym Jones.) But Coach remained bitter, angered that so much attention followed the film training, and he accused Twight of pilfering copyrighted CrossFit material for his military seminars.

"Here's proof of the authenticity of Mark Twight's program," Glassman wrote in an e-mail. "Mark was caught stealing my work, re-copyrighting it and selling it to the Navy … Gym Jones is an excellent program. I am its author/inventor/developer."

Twight laughed when I told him this, though he acknowledges using some of the CrossFit teachings. "Is what we do derivative?" he said. "Of course it is. Everything is. C'mon, we're just picking shit up and putting it down. I won't let my personal falling-out alter my respect for what Greg's done and what he's taught me … but it wasn't the end-all, be-all. My mistake when I separated was not separating fully enough. I was lazy and I fucked up. But what I do now comes from a lot of places—his material, my material, and many others."