7:30 AM ET

Anthony Robles is crutching quickly.

Robles, the NCAA champion wrestler at Arizona State who has one leg, is skiing in the air even though he has two backpacks around his wrists and a box in his hands. The crutches he uses are so strong and calloused that they can squeeze and push and pull just like hands. He can crutch a mile in 8 minutes.

Robles is going to the headquarters of the Desert Financial Credit Union in Phoenix to attempt to break the world record for pullups in 24 hours.

Robles and his wife paused for a moment in the middle of the room to get a lay of the land with 62 minutes left. A group of people from Guinness World Record are preparing to live stream the entire day.

Two ways to set a Guinness record. It is possible to film and document everything yourself and submit it to Guinness for an evaluation. It can take a long time to get back to you. To get the U.K.-based Guinness to come in person with cameras and judges is one of the perks. Robles' manager said that the total cost was around $15,000.

Several credit union employees have set up food and drinks on a table for the production team, just on the other side of a roped off viewing area with space for about 50 members of the general public. Robles is in the middle of a room with a pullup station. He has a green papasan chair a foot away from the bar and a wooden plank that he can use to jump onto the bar.

Before the 9 a.m. start time, he surveys everything and heads into the far right corner to a curtained off area for Robles, his wife, Laura, and mom, Judy. The story of a boy with one leg growing up to become the nation's most dominant college wrestler is unlikely, but the same kid could become the greatest pullup machine in history. He currently holds the record for the most pullups in a single minute with an 80 pound weight on his back. He's attempting to pull up 7,716 pullups in a day.

He will be done with this. Laura found out she's pregnant after he took over as head wrestling coach. He says he's ready to move on from his athletic career. He wanted to live up to the title of his book "Unstoppable: From Underdog to Undefeated: How I became a champion." He has been training for almost two years to go out with a bang.

"I'm excited about this next chapter of my life, I promised Laura that this would be it," Robles said, nodding toward his wife. After laying his crutches down in the back, he rests for a bit before starting his journey.

He says it will be the most difficult thing he has ever done. I am pretty sure I will do it. Then I can leave.

Robles attempts to break the pullup record in Phoenix. His gameplan? Knock out 12 pullups per minute. Caitlin O'Hara for ESPN

There have been more fitness fads in the past 50 years. I remember Bowflex. What's the name of the game? What about Jake's body? Some old-school exercises are no longer relevant. According to a recent story in The Atlantic, the situp is outdated and potentially dangerous to the spine and core. It's the same thing with crunches.

The pullup is next to the pushup and squat as the defending champion of strength training. Pullups with palms facing inward are considered chin-ups. Pullups are used by the U.S. armed forces as a training evaluator. It's very difficult to do them.

Pete says the pullup is a great exercise. You don't have to have fancy equipment. It's a good standard for testing strength.

Ten years ago, David Goggins was interested in that. Goggins had become a legend in the fitness world by the time he wrote his book. Goggins has been alive for three lifetimes.

He describes in the book how he wanted to set a world record for the most pullups in a day. Stephen Hyland, the legendary British fitness guru who is 69 years old, established the number 4,020 in 2011.

David Goggins with Senator Marsha Blackburn before former President Trump's State of the Union on February 4, 2020. Alex Brandon/AP

The absurdity of trying to do so many pullups over a long period of time made Goggins happy. It would require a certain amount of precision and recklessness. Goggins appeared on the "Today" show three times. He came down with rhabdomyolysis after turning his hands into hamburger meat. About 3% of people with rhabdo die from it every year, and Rhabdo is the body's way of screaming to stop doing physical activity. For people like Goggins, it is the number one concern.

It is part of the attraction.

Goggins kept going. He broke the record on his third try. The pullup record attempts of Goggins began to drum up interest. The grand finale of the book is the pullup record. The memoir sold four million copies.

Goggins made the pullup cool and set off a arms race. The record may have set a record for most attempts and most breaks over the last nine years. The current pullup record has almost doubled since Goggins was able to get to 4,030.

Robles focused on one-minute pullup records with a lot of weight on his back after reading the book. He helped boost pullups to the world record A-list, too, and he loved competing in front of large crowds.

Robles and pullups are very poetic. The sport of wrestling requires a kind of ruthless cruelness that is celebrated. Robles' chin was wiped across the mat over and over again during his first few years in high school. Robles used a style that became a metaphor for how he lived. He stayed grounded, his one leg bent under his torso, waiting for the right moment, then he would surge forward and topple people with his speed and strength.

He sees himself as a snake. I'm not that risky. I can hit when I'm coiled up. I'm deadly that time.

Robles dominated the 125-pound weight class during his four years at Arizona State University. He ended with a 122-23 record and took home a National Championship in 2011. Hunter Martin/Getty Images

He was able to control his opponent. He put a 125-pound blanket on their backs and brutalized them from the top position. Phil Knight called him the greatest athletic accomplishment he'd ever seen when he won a national title in 2011. Robles does pullups, drawing himself toward the sky, is a beautiful coda to the sports story that began on the wrestling mat.

The more he thought about Goggins' book, the more he wanted to do the 24 hour challenge. Around the same time Robles decided to break Goggins' record, a lonely former Army Ranger in Georgia made the same decision.

Brandon was going to be an army lifer. He became a member of the Rangers after a long Army career. He was discharged from the hospital after a medical check found he had ulcerative colitis. Around the time his marriage fell apart, he was unsure of what to do with his life. He decided to take a job as a personal trainer in Columbus, Georgia.

He would ask himself what he was supposed to do. He would shrug. He had no idea.

After reading Goggins' book, he began writing down the pullup record on paper. His training wasn't very good. He would power through 11 or 26 on the pullup bar while working out.

He did 26 because he always threw one in for his Airborne Ranger in the Sky who was killed in Afghanistan. Army Rangers try to think of and honor dead soldiers every day. One extra rep is tacked on to every set for the Airborne Ranger in the sky. He says the goal is to keep the soldier's memory alive.

Tucker sat down with a potential client to sign her up for a gym membership and begin to map out her goals. She pointed at a note on the wall in the office and asked what it was.

Tucker chuckled and said that he had come up with a stupid goal for himself. Don't pay attention to it. She was asked for her name.

She waited until he said her last name. "Kubik" is a word

Tucker stopped writing the "K"

He said that it was weird. Do you know someone named Ron?

Her eyes grew larger. She said that she was her brother.

The Army Ranger who did extra pullup reps every day in his honor as he looked for meaning in his own life had electricity shoot up his spine as he sat down with Ron's sister. Mary finished up her application after they talked about Ron for a while. She pointed at the board. She told them to try to break the record.

Tucker said it would be difficult to put together a team, find camera people and pay for the Guinness application, so he blew her off.

She said she was an eventplanner. Everything will be set up by me. We can do this together.

So they did. Tucker set up shop in the back of the gym after reading about the record in the book. Tucker followed a very strict strategy he had built for himself: three pullups every 30 seconds, with almost no breaks, over and over and over again for 24 hours.

Brandon Tucker, a former U.S. Army Ranger, performs a muscle up in January. Tucker holds the current record for performing the most pullups in 24 hours. Alex Skowronski/Columbus Dispatch via USA Today Network

He blew past Goggins' original record by the halfway point and still felt good. Tucker couldn't sleep when he tried to sleep for half an hour. After 30 minutes of staring at his eyes, he came back out.

Brandon Tucker did 7,715 pullups in less than 10 minutes. He couldn't believe the damage done to his hands and his muscles were sore. He tried running his hands through a bucket of rice to dry them and soothe them between sets. There was still more skin torn off than left behind.

After sleeping for 12 hours the next day, he couldn't stand up to leave his bed. He didn't notice how badly his calves and toes had been damaged. His calves were barking for a week after he jumped onto the pullup bar.

Tucker was barely able to stand up as his dad fixed him some food in the other room and he waited for his mom to make him lunch. He kept thinking about the number 7,715, and how he'd set a goal, and then he demolished the world's most renowned fitness record.

He couldn't help but think how difficult it would be for the next person to beat it, and he wondered if that person was him.

Robles had a plan if Tucker was the culprit. He wanted to do a lot of pullups for a long time. He did as many as 750 pullups per hour and did as many as 4,700 pullups in nine hours. He was fond of the idea of getting ahead of the pace and building a buffer.

Robles' record attempt is no different than any other game day, it's always a little different. Robles was surprised when Guinness' stream went live at 8:55 a.m. before the 9 a.m. start.

Robles jumped out of his chair and onto the bar when he was told the clock was at 9 a.m.

Laura yelled "you got this" as the attempt began.

He goes through 12 pullups in 13 seconds. Robles wants the clock to read 1 minute as he hits the bar, then he wants to rip off as many pullups as possible in the next 15-20 seconds, before anchoring down in his chair. He wants to do it all over again for 1,250 minutes of the day's total minutes.

It's difficult to watch Robles work out on the bar and then collapse into the chair and stare at the clock. He had to work for 45 seconds to catch his breath.

He scored his first 12. Several TV crews are filming live, as well as the Guinness stream on the internet. Two paramedics in orange shirts that simply say "Medical" on the back eat breakfast as Robles' two officials talk about his first set.

Guinness requires the counters to track every single pullup individually and then confirm the total when Robles stops. Guinness guidelines require two new counters every four hours because of how tiring it can be to count a preposterous athletic feat in front of them.

Robles goes through 12 in the next minute and 12 in the third minute. He's at 36 pullups, and it's 9:03 a.m., and the people in the room are cheering him on. Robles listens to a mix of music. His open ear is supposed to be used by his trainers to help him improve. Robles smiles at the crowd for one of the only times of the day, which makes them happy.

He has 218 pullups and the first sign of trouble is on his face. His trainers let him know that his heart rate was too high. Between the first 19 sets and the stimulation of a crowd cheering for him, Robles felt off.

If they can get his heart rate down a bit, he's been told to cut his reps in half. Gary Lewis said it was a mini anxiety attack. He'll be okay.

Lewis is an interesting person. When he was 60 years old, he was a former TV producer who was dabbling in managing athletes' careers. He was expecting to retire by now. He adores Robles and marvels at his ability to never accept the limitations of the body given to him.

Michael Jordan is one of the athletes Lewis has worked with. I have never met Anthony Robles. Nobody has his mental makeup.

Robles rests between sets as his wife Laura massages his forearm. He promised her this would be his final attempt to break such a physically taxing fitness record. Caitlin O'Hara for ESPN

Robles' heart rate is fine and his pullup count has gone up. He's shoveling down energy bars and water between sets to make up for the calories burned. Three credit union security guards stopped by to watch him as he went to the bathroom.

He is back on the bar by 10:00 a.m. They've been working together for almost two years and their bond is special. Robles' head goes up and down quickly as he listens, and he has a lot of eagerness in his eyes. He's the star of the show and everyone in his satellites watch him. He looks like a new boxer between rounds, trying to absorb every word of his coach.

Robles is ahead of the record-breaking pace with 745 pullups. There are more flags going up. He has a knot on his forearm and his wife and trainer hit him with a massage gun.

They warm up small heat packs in a slow cooker when that doesn't work. One of the packs got too hot and ripped a dime-sized piece of skin off Robles. He is not going to be taken lightly. Robles has never met his father. He was ostracized and pushed around for being the kid with one leg, and even though he fell in love with wrestling, he took a lot bigger than the ones his wife is using. There is a wrist burn.

He hits 1,000 pullups at 11:01 a.m., and he's at 1,912 when two new counters come in. Robles' friends and wrestling coaches have been told to be ruthless about his pulls. Robles had had a few sets where his chin didn't come completely over the bar. They are told that they can't count them.

Robles is 1,100 ahead of the pace to break the record at the six hour mark. The plan was for him to get out of the gate and take a break around this point.

Robles walks out of the room on crutches. Robles is going to lay down on an air mattress in an old bank vault, but he won't be able to see it.

Two kids, a boy and a girl, both under the age of 12 are standing at the roped off area. The boy says that Robles is going to do it. He is going to be the pullup king.

Robles stretches while talking with his mom Dr. Judy Robles, an assistant dean at Arizona State. "I'm not really nervous," she said. "I know he's going to do it." Caitlin O'Hara for ESPN

He focused on his speed and power when he first started doing martial arts. He briefly held the world record with 62 pullups in 60 seconds at the 2 minute warning of a Jets game.

Robles ended up in a credit union lobby, crutching back from a half-hour break, because he wondered how he'd do in a more punishing test of his body.

Robles is at the bar at precisely 3 p.m. He is at a high pace and is at 2,380 by 1:45 pm. He needs 5,000 more to get within striking distance, but these are the dog days of the challenge, with a waning crowd.

Laura and Hicks are working over his wrists with the massage guns, and Robles is trying to get to 2,500. Robles is on track for around 8,500 pullups, even with some breaks built in. He's at 2,691 by 5 p.m., when Hicks helps him grab his crutches to head for the vault for a planned 45 minute break.

His mom decided to leave the room at the same time as she changed her outfit. She is an assistant dean at Arizona State and has been keeping an eye on her son. When she asked why her baby boy didn't have a second leg, the doctors shrugged and she never got a better answer. After giving birth to Anthony, she dropped out of high school and got her GED. She earned her doctorate a few weeks ago. She is as strong as her son.

Dr. Judith Robles was replaced by Anthony Robles' mother, Judy, after she returned to the room. They like the Raiders.

For the first time all day, she doesn't have a computer. He is going to do it.

Robles is at the bar again at precisely 5:45 p.m. The crowd of 25 roars when he starts cranking out eight. He needs this second shift of supporters to get him through the night.

At 5:52 p.m., he did his first one and then dropped down from the bar with a horrified look on his face. A bag of ice is pulled out by a man who is massaging his bicep.

The game plan was for Hicks to leave by now. He decided to stay on because he loves Robles. It was difficult to not notice that he was staring up at Robles all day and that he was pushing his chin over an imaginary bar with Robles by his side. It had been almost two years since the two of them were at a pullup bar.

The room is silent. A medic takes the lead when the medical team arrives. He rubs his hands over Robles. They're whispering in a room full of people, but it's so quiet that you can't hear what they're saying.

The paramedic asked Hicks to look at a spot on Robles' arm, but he couldn't tell if it was a tear or not.

Let's give it time.

There are four minutes left. Then seven. Robles only makes it halfway after trying a second pullup. He hops on the bar for a second time. He only makes it halfway before falling. There is more whispering as the paramedic looks at his bicep.

If you were my son, I would tell you to stop, said the paramedic as he looked up at Robles.

Robles reaches down and pulls his black sleeveless shirt up over his head as Laura stands beside him. Nobody would like to say it out loud. You can hear the crunch of the paper towels on Robles' eyes as he rubs some around his eyes. In the room, it's gone beyond silent.

Robles reached for his crutches as the paramedic said he would be afraid to risk further injury.

Team Robles disappears behind a small curtained off area as he heads away from the bar. The room is staring at the black board with the bright red numbers on it, Robles' count at the time of the injury.

Out of view for most of the room, the paramedic stands and walks away from the pullup area. He found a spot next to the mounds of wraps and sandwiches and leaned against the wall. The paramedic would have started crying if everyone else in the room hadn't been crying.

Laura Robles comforts Anthony as he decides whether to stop the challenge. The former wrestling champ attempted one more set before calling it off. Caitlin O'Hara for ESPN

Robles had crutches and was going to stand in front of the Guinness cameras. Lucas announced that Robles had injured his bicep and turned it over to him.

Bruce Lee said, "Not failure, but low aim, is the crime." Even if it fails, it's wonderful. He thanks everyone who came out and said he felt great after his break, but then something popped in his bicep.

Robles starts to cry as he breathes in a lot of air, maybe more than he ever did during the pullup record attempt. He says that it hurts. Whether I was going to break the record or not, I did my best. I was going to die at that point. I wasn't able to do that. It was still my finest.

She is probably going to fall apart according to Graham. Employees of the credit union talked about Robles all day long. The bond between bankers and their athletes probably sounds funny to anyone with an ounce of cynicism. Robles has the ability to unite credit union workers, paramedics, 12-year-olds and anyone in between.

Graham tries to read "The Man in the Arena" but she can't. The entire room is a mess.

It's a good mess. This had been a success. The crowd is standing and clapping.

Robles thanked the people who came out to support him. "I'm going to get this checked out, then we'll see what to do next," he said many times. Robles gets into the passenger seat of his car in the parking lot.

Anthony Robles went to the emergency room 12 hours later.

Robles wipes away tears after ending his attempt. He's vowed, with his wife Laura's blessing, that he'll be back once he's fully healed. Caitlin O'Hara for ESPN

A few weeks before his death, Robles is on a call talking about his last athletic challenge. He says he's done everything he could. I don't have anything to prove.

He is a wrestling coach at Mesa High and Laura is a real estate agent. Robles likes to help out on the dirty side of her business.

He promised Laura that this would be it and then stopped.

He is looking away from his camera. He talked about how he wants to be a good father to Laura.

He says he's about to become a father. I am the head coach of a high school program that is special to me. Those are the challenges I will face in the future. I don't know how to be the best dad. I don't know how to be the best coach. How can I make a difference to these kids? My life is going to be that.

Robles was told in the emergency room that he tore a bicep but not the bicep itself. Robles might not have been able to do a pullup again if the doctor hadn't listened to the paramedics.

Tucker's record is so difficult due to that. It makes you wonder what the actual maximum human capacity would be. Tucker believes a human could do as many as 10,000 pullups. Robles said he thought he could get to 9,000. Anthony could have done many more things. I know it and he knows it.

This story has a plot twist that you probably smelled fifteen minutes ago. Robles said on the call that he's looking forward to having kids and coaching Mesa High and demo-ing some walls for Laura, but he's ready to go on another run at the pullup record as soon as his arms are strong.

He was crying behind the curtain when Laura said, "I know how much this means to you." Let's go if you want to go for it a second time.

He will return it by the end of 2022. He may have some competition. Tucker and Robles have both heard from other fitness-heads who say they are coming for the record.

Supporters congratulate Robles after he stopped his attempt. With his wife Laura's blessing, he's vowed that he'll return once he's fully healed. Caitlin O'Hara for ESPN

Tucker thought Robles would beat his 24 hour record, so he started scheming out a plan to beat it with an 80 pound weight on his back. He admits he might get sucked back into the pullup record that David Goggins introduced to the world if he goes after something.

He says it's not about the records for him and Anthony. I hope he breaks it because I will always know what I did, the price that I paid to set the record, and that someone else paid that price as well.

Robles says that he can live with not breaking the record if he doesn't get injured. He sounds like a man who really believes he will win the world pullup record.

He says he's ready to uncoil one final time.