The format of The Ultimate Fighter has changed little over the years. Fighters live and train together, then fight their way to “a contract” (though, usually, multiple fighters end up in the UFC).

But the show has evolved a bit over the years. If you were frozen in a cave after Season 2 and thawed out to see Season 24, you’re probably wondering what happened to the “challenges,” when the UFC and show producers tested fighters’ worthiness by having them tread water, split logs or compete in some other sort of activity not really related to fighting.

In Season 1, before anyone stepped into fight, fighters turned up three times to greet entertainer Willa Ford, who would explain the competition and its stakes.

In the first two challenges, the losing team had to pick a fighter to be sent home without fighting. Coach Randy Couture picked Jason Thacker, whose unfortunate story was the subject of a harrowing Chuck Mindenhall piece that prompted an outpouring of support from the MMA community and this thank-you video from the man himself:

Then Josh Koscheck’s surprising lumberjack skills forced Couture to send home another fighter — Chris Sanford, a controversial choice over Chris Leben.

“We didn’t come here to lift logs or carry someone around on an easy chair,” Nate Quarry said as he stared into America’s soul in a confessional.

The third episode packed in a lot of memorable moments: Dana White’s “Do you wanna be a f—in’ fighter” speech, Bobby Southworth’s weight cut and Southworth’s knockout in one of the first MMA fights on U.S. television. But the only reason Southworth had to go through that weight cut and fight is that he lost an individual challenge involving kayaks and weights.

So these challenges weren’t mere sideshows. They dictated team strategy. Teams might pick a fight to eliminate someone they thought was good at challenges but not as good in the cage. Quarry wondered aloud if his team could benefit from getting someone the same height as his teammates, all the better for carrying logs and beams together. Rich Franklin cleverly forfeited a challenge after letting two of Matt Hughes’ fighters wear themselves out.

But by Season 3, producers had seen enough.

“We eliminated the physical challenges a while ago because we ran into a situation where it was, in the end, not great for the fighters physically, and it didn’t have a positive impact on the reason why they were there, which was to fight,” then-Spike executive Brian Diamond said. “So we basically segued that into the coaches’ challenge, where we make it something fun and interesting and light.”

(It’s still hard to top the first coaches’ challenge, in which Ken Shamrock showed off his pool-hustling skills against a stunned Tito Ortiz, though Conor McGregor and Urijah Faber chucking watermelons from a helicopter was amusing as well.)

Amir Sadollah, talking TUF with fans assembled before the 13th season finale, said he wouldn’t mind seeing the challenges return. “I would throw some challenges in there. Some Survivor-type things. They should probably not put me in charge of that.”

By TUF 3, the now-familiar format took hold — Dana White flips a coin, the winning coach can choose either the first draft pick or the first fight, and whoever wins sets the next fight. Also, each winning fighter advanced to the next round, a change from TUF 1 and 2, in which some fighters had already fought twice before the semifinals while others hadn’t fought at all.

Starting with TUF 7, fighters had to fight before they unpacked.

The Ultimate Fighter keeps a lot of secrets. But no one was shocked more than the TUF 7 cast members who strutted into the UFC training center and quickly realized they had far more than 16 people in the room.

Enter Dana White, with a devious smile and another classic sound bite at the ready:

“What I get tired of every season are the pussies and posers who come on this show. … It makes me sick to my stomach because I think of all the guys who wanted to be there. I found the (bleeping) solution. … This season, you’re going to fight your way onto the show.”

Silence. Jaws dropped. “I think some of them crapped their pants,” quipped coach Quinton “Rampage” Jackson on camera. “I smelled it.”

TUF had experimented with a “fight to get in” in Season 2. They brought in nine fighters per weight class with the intention of making the weakest fighters, based on assessment in whatever fitness tests the coaches had in mind, fight each other and send the loser home early. They wound up getting no extra fights out of the idea. In the heavyweight class, Eli Joslin left and Kerry Schall was hurt. Kenny Stevens was called out as the weakest welterweight and was given a chance to fight for his spot, but he couldn’t make weight.

In TUF 7, despite the short notice (24 hours), everyone made weight. And the fights were all pretty good. Dana White was happy: “We came up with this concept to get rid of the pussies and the posers. There’s none here in this room today.” (And yes, we do need to ask when we’re going to stop using “pussies” as a synonym for “weaklings.” It’s the 21st century, guys, and scores of stand-up comics have pointed out how the word really doesn’t fit by any logic whatsoever.)

It’s good how they surprise guys with it. Too many guys were just showing up to be there. They weren’t showing up ready. - Ed Herman

“It’s good how they surprise guys with it. Too many guys were just showing up to be there. They weren’t showing up ready. I made that same mistake. I wasn’t as ready as I could’ve been showing up.”

But these fights have a drawback: One slip-up or one bad decision can keep a good fighter or good personality out of the house.

In the TUF 8 prelims, Eliot Marshall lost a curious decision to Karn Grigoryan. He only made it back into the house through an injury to Antwain Britt, who had beaten top prospect Ryan Jimmo.

In the Team UK prelims for TUF 9, Michael Bisping rated veteran Che Mills as one of the favorites. He landed a few good shots against James Wilks, then got caught in a heel hook and tapped out. Wilks went on to win the season. Mills went back to smaller cards but wound up in the co-main event of a major UFC pay-per-view just a couple of years later. Then the show lost a compelling character in Alex Reid, who’s enough of a celebrity in the UK to be on Celebrity Big Brother. He lost an entertaining fight against Dean Amasinger.

Nam Phan looked like a bit of a ringer coming into TUF 12, boasting experience in Strikeforce and Sengoku. His preliminary opponent: Mike Budnik, who had the terrific back story of making the transition from the X Games to a strong MMA career. Phan said with a laugh that he was a little surprised:

“It was so weird! They’re pairing me up against a tough guy. The guy’s got a winning record and a lot of tough fights in WEC. Maybe they don’t want me to get in the house, you know! … I told my academy I’d be going to Vegas for six weeks. I felt like it was life-or-death. This is my career. If I don’t get on this show, I’m not going to make it in mixed martial arts. I’ve gotta get on this show, I’ve gotta make it. If I didn’t win that fight to get in the house, I would’ve stayed in Vegas another six weeks and pretended like I got in the house.”

It was especially strange because Phan was fast-tracked through the audition process. He said he was supposed to fight in the fifth season but signed with Strikeforce instead, suggesting Andy Wang to take his spot. When he returned for the 12th season, he didn’t have to start from scratch.

“I didn’t really have to go through the whole audition. They already knew who I was. They said just go to the interview in Vegas.”

The preliminary bouts were dropped for TUF 10, the heavyweight season featuring Kimbo Slice and Roy Nelson. The UFC and Spike surely didn’t want to risk a Kimbo loss in the first episode, and given the talent pool in that class, they may not have found 32 fighters worth bringing in.

TUF 11 reinstated the preliminary bouts and added another layer — the wild-card bout. Only 14 fighters were in the house, and two first-round losers were given a chance to fight again. The show also stuck with a single weight class, which meant fighters were asked to fight a lot. Here’s Kris McCray’s itinerary for the first few weeks of 2010, according to Nevada commission records:

Jan. 23: beat Cleburn Walker by first-round submission (preliminary fight)

Feb. 8: lost to Josh Bryant by three-round (sudden victory) unanimous decision (round of 16)

Feb. 16: beat Kyacey Uscola by second-round submission (wild-card fight)

Feb. 23: beat Kyle Noke by three-round (sudden victory) unanimous decision (quarterfinals)

March 2: beat Josh Bryant by three-round unanimous decision (semifinals)

McCray lost to Court McGee in the June 19 finale and lost his next two UFC fights before getting dropped.

The wild card led to some ridiculous politics. Here’s a piece of advice for future TUF contestants: When a vacancy arises in a tournament, run up to Dana White and/or the coaches. Throw the nearest piece of furniture, preferably in a direction in which no one gets hurt. (The message might be lost if someone ends up in the hospital.) Say you’ll cut off your leg to make weight, and you’ll fight Daniel Cormier and Stipe Miocic with both arms tied behind your back just for the opportunity to get back into the cage.

The wild card and the fights to get into the house have been cut and reinstated several times. In TUF 13, when the fights were dropped, Keon Caldwell struggled in training and decided to leave the show. A displeased White was determined to weed out similar fighters in the future, even to the point of using one-round fights for TUF 15, when the fights aired live. Some seasons went on without risking any cast members in a preliminary round, while others bid an early farewell to intriguing talents such as Tonya Evinger, Valerie Letourneau, Tara LaRosa and Nordine Taleb (a veteran of TUF: Canada vs. Australia who couldn’t fight his way into the TUF 19 house).

(Why it hasn’t occurred to anyone to use wild-card slots on people who impress but lose in their “fights to get in the house” is beyond me. The ideal TUF format: 12 fighters per weight class, with six preliminary winners and two “wild cards” advancing to the house. The 28-fighter brackets just invite more fight schedules like McCray’s.)

The stakes of the tournament have also changed a bit over time. The winner still gets a few handsome rewards and a UFC contract, but the show acknowledges that a lot of fighters will go on to carve out UFC careers. Some seasons have had a novel hook. TUF 20 determined the first women’s strawweight champion. TUF 21 pitted two rival South Florida gyms against each other. TUF 24 pulled together 16 flyweight champions from other promotions in an effort to find a worthy challenger for dominant Demetrious Johnson. Some tournaments have been pre-seeded, like March Madness.

And special guests appear from time to time, sometimes awkwardly. A couple of seasons before she coached on the show, Ronda Rousey led a grappling session and then visited the house to watch a UFC event with the guys on TUF 15, who had been cooped up in the house far longer than previous TUF contestants. Dominick Cruz warned her she was going into a “lion’s den.”

“It’s a lot of guys to fend off at once,” Rousey said.

Maybe Rousey, Cruz and the producers were expecting something different. What they got was a house full of guys who, predictably and wisely, didn’t want to make idiots of themselves while wearing microphones in a house that has cameras everywhere.

And because this was the “live” season of The Ultimate Fighter, with each fight broadcast live over a 12-week season, the fighters had spent twice as long in confinement as previous casts. It’s safe to say things had gotten a little weird:

Aside from the tournament format, most aspects of The Ultimate Fighter were remarkably consistent. The graphics and music didn’t change until the show moved to FX for the 15th season, which was also the only season with live fights.

A lot of the crew stuck around for much of the show’s run, for which Diamond praises executive producer Craig Piligian:

A lot of people really like working on the show, and we’ve pretty much maintained a consistent crew through the years. ... They can anticipate how to deal with certain situations and how to capture it. A lot of these guys are pretty athletic and quick on their feet. - Brian Diamond

“He knows how to run the operation in such a way that we’ll never miss anything, but he’s also not burning his people out at the same time. A lot of people really like working on the show, and we’ve pretty much maintained a consistent crew through the years. Which is helpful. There’s no learning curve, and everybody knows what the basic play is going in. They can anticipate how to deal with certain situations and how to capture it. A lot of these guys are pretty athletic and quick on their feet.”

Many changes through the years were subtle. The UFC built a second entrance to its training center to allow the crew to get in and out without getting mixed with emotional fighters heading to or from the cage. TUF 1 had more exposition and explanation than future seasons, along with graphics telling us which day we were watching -- “Day 13” was the start of Bobby Southworth’s weight-cutting saga; “Day 21” was the day Dana White and company sat down with Southworth, Chris Leben, Josh Koscheck and Nate Quarry to sort through an incident in the house.

A more compelling change: Losing fighters stay in the house. That came as a surprise to the TUF 5 cast, which didn’t know the rules had changed until Allen Berube lost the first fight and cheerfully strolled back into the house to announce he was staying. Some fighters worried about others sticking around when they don’t have incentive to train seriously and may get rowdy while the survivors are trying to sleep. That’s called “foreshadowing,” given what happened with Berube and company later in the season.

TUF 2’s Tom Murphy was glad he didn’t stick around after losing his bout. “I don’t think I would’ve wanted to stay in the house. I wasn’t there to promote myself and to be a spectacle. I was there to compete against these other athletes.”

Not that losing in the early seasons was a ticket to a better place. Defeated fighters went into a strange sort of limbo, still isolated from society but no longer a part of the show.

Murphy elaborates: “They had two different houses – condos with a bunch of rooms. You’d just kind hang out by the pool, go to the gym. You don’t do too much. It was awful. They still wouldn’t let you call anybody, they wouldn’t let you do anything. They let you watch TV and they took you out to eat every now and then or to a movie, but you weren’t allowed to talk about what you were doing.”

But at least he didn’t have to participate in any more challenges.

For the sake of posterity, though, let’s take a look back at the gone-but-not-forgotten TUF challenges:

Season 1

Episode 2, light heavyweights: Each team of four fighters had to carry its coach, sitting in an easy chair strapped to a big plank of wood, over and under some bars before trudging through Lake Mead. Team Couture nearly dropped Randy Couture in the water, with Jason Thacker struggling in particular. Couture was forced to let a fighter go. He said kind words about Thacker’s resilience, but the Canadian was out. He got consoling hugs from several fighters and coaches, not just on his own team. Bobby Southworth pulled him close and told him, “Keep your chin up, square your shoulders. Stand up strong. Walk out of here like the warrior you are.”

Episode 2, middleweights: Carry telephone poles, saw them apart, carry the pieces, reattach them, carry them across the finish line. Led by Josh Koscheck’s wizardry with a saw, Team Liddell won easily. When Couture narrowed his potential cuts to two, Chris Sanford immediately went after Chris Leben, Apprentice-style. A chastened Leben responded with humility, and Couture kept him.

Episode 3, light heavyweights: An individual challenge — pull yourself on a kayak, then carry weights. Last-place finisher has to fight but can pick the opponent from the other team. Alex Karalexis flew through it, prompting this wisecrack from Mike Swick: “He was hauling ass. And that tells me that man did not wanna fight. I have not seen that man move like that seriously in the two weeks we’ve been here. No one has seen him move like that.” Lodune Sincaid jokes that he would have had time to write a novel and knit a sweater and still beat Bobby Southworth, who more or less gave up and started thinking about his weight cut. But once Southworth made weight, beating chosen foe Sincaid wasn’t much of a challenge.

Episode 4, middleweights: Chris Leben volunteered to tank the challenge so he could pick a fight with Koscheck, seen as a valuable challenge-winner but an inexperienced fighter at the time. But Willa Ford had a surprise. The team that won the challenge, some sort of obstacle course with medicine balls, would pick the next fight. Team Liddell's Koscheck and Diego Sanchez won, spoiling the Leben/Couture strategy. Liddell picked Sanchez to dispatch Karalexis in the cage.

Episodes 5-6: No challenge -- Dana White decided to get it over with and put the feuding Koscheck and Leben in the cage together. Koscheck eliminated Leben — for the moment.

Episode 7, light heavyweights: Six-way tug-of-war. Team Couture finally won, while Team Liddell questioned Sam Hoger's effort. Couture made the gutsy call to send Stephan Bonnar against tournament favorite Southworth, and the future finalist pulled out a split decision.

Episode 8, middleweights: Leben returned because of Nate Quarry's injury, and he and Josh Rafferty dragged 200-pound bags through mud faster than their Team Liddell counterparts. For some reason, they sent the sulking, overmatched Rafferty against eventual champion Sanchez.

Episode 9, light heavyweights: Stack cases of water for the right to drop the opposing coach in a dunking booth. Team Liddell won, and Sam Hoger griped that his team was praising Forrest Griffin and ignoring his contributions. Griffin beat Alex Schoenauer in the cage.

Season 2

Episode 2, welterweights: "Capture the dummy." Luke Cummo came up with the bright idea of wrapping up two guys from Team Franklin, making it easy to Team Hughes to drag the dummy home, and Josh Burkman duly took out Melvin Guillard.

Episode 3, heavyweights: Each team has to tread water and keep a team banner above the pool's surface. Rashad Evans struggled and blamed himself for Team Franklin's loss. But Team Hughes botched the fight pick, sending Rob MacDonald against the underrated Brad Imes.

Episode 4, welterweights: "Hangman," in which fighters hang from monkey bars and attack each other, with the winner being the last one hanging. Jorge Gurgel embedded himself in the bars to win it for Team Franklin, but Marcus Davis insisted on challenging himself against eventual champion Joe Stevenson.

Episode 5, heavyweights: To Dana White's amusement, the heavyweights competed in the Octagon, scrapping to remove each other's socks. "I guess it's something wrestlers do," White said on the show. "Or little kids at pajama parties." Mike Whitehead's sock-pulling technique led Team Hughes to victory, and Hughes talked trash for the rest of the episode -- until Rashad Evans beats the injured Tom Murphy.

Episode 6, both classes: The breaking point was probably the “scarecrow” challenge, in which a welterweight climbed up on a standing heavyweight, then pulled himself around the heavyweight’s body as many times as possible without touching the floor. Joe Stevenson was impressive, making more than 200 revolutions around big Mike Whitehead and talking smack to Jorge Gurgel, who was loosening up take his turn for Team Franklin. But when Stevenson finally fell after more than an hour and a half of work, the poker-faced Franklin revealed his plan. He forfeited. Gurgel wasn’t happy, but Franklin calmed him down, and he recovered far more quickly then Stevenson and Whitehead did. Still, Team Hughes won the fight, more or less — team pariah Jason Von Flue beat Gurgel.

Episode 7, heavyweights: Mud wrestling. Seriously. Evans and Imes got Dan Christison out, then quickly ganged up on Whitehead to claim the win for Team Franklin. Hughes critiqued their performance in the van ride home, and future Kimbo Slice opponent Seth Petruzelli eliminated Christison.

Episode 8, welterweights: "Randy Says," a Simon Says game in which Couture called out various striking combinations. Team Hughes won, and Luke Cummo went on to beat Anthony Torres.

Episode 9, heavyweights: A variant on Season 1's tug-of-war game, which seemed unfairly stacked against smaller heavyweights Evans and Keith Jardine. Team Hughes won the challenge but lost the fight, with Evans upsetting Whitehead. (Well, at the time it seemed like an upset.)

A quick note on quotes: When quotes are taken from TUF broadcasts, books or other sources, they are attributed as such. Unattributed quotes are taken from first-hand interviews for the book Inside The Ultimate Fighter, which was never published. See the intro to this series to see what happened to that book.

Next week: The talent pool gets deeper, then shallower.