In the past 15 years, stories about LeBron James' body have become a bit legendary with teammates.

Seeing him turn his ankle nearly 90 degrees only to tighten his shoelaces and finish with a triple-double. Watching him show up four hours before a playoff game to get in a sweat-soaked workout, then play more than 40 minutes and score 40 points. And the topper: the time James gained seven pounds during an Eastern Conference finals game.

Some Miami Heat teammates saw the scale and attest to it in amazement. James himself just shrugs and calls it "weird as hell." The truly wild part is that it was from 271 pounds to 278 pounds, though James is much lighter these days.

It all gives the impression that James is invincible. Of course, that isn't true. James' athleticism is the product of genetics and work -- not just in the number of hours, but also in his thoughtful and ever-evolving approach toward training and recovery.

A few years ago, James did run into a problem, a serious issue that for the first time truly threatened to derail his career. He had disc issues in his lower back that were zapping his strength and bounce. He didn't talk about them much, and he tried his best to play through them. But James -- video and stats showed -- was weakening.

Now, it's hard to fathom. Now, he's seen plucking a steal from midair in Phoenix last week and throwing down a windmill dunk that had people pulling out video from 2003 for comparison. Then, there was the dunk in Portland over Jusuf Nurkic, which had as much explosion and power as any move of James' long career.

That's just a recap of the past few days. From November, when James scored a Cavaliers career-high 57 points in a game, to February, when he averaged a triple-double for the month, James has repeatedly said this is the best he has ever felt. On Monday against the Milwaukee Bucks (7 p.m. ET on ESPN), James will play in his 70th consecutive game as he chases the first season in which he plays in all 82 games.

Back in 2015, however, James was laying on the court during timeouts, propped on a towel in discomfort. It brought to mind Larry Bird and Steve Nash, all-time greats who saw their careers zapped in their 30s because of back issues.

James needed two anti-inflammatory injections in his lower back in a 10-month span in 2015, one shutting him down for two weeks at midseason and another wiping out his preseason. And the possibility was left open that he might need more numbing shots, an indication he was dealing with something serious.

Concerned, James called in a specialist, a quiet and unassuming man who has been around the Cavs nearly every day for the past three seasons but who largely goes unnoticed, even as the product of his work is on display with James nightly. He is Donnie Raimon, James' personal biomechanist -- a specialist in human movement who combines biology and physical mechanics -- and the man who has helped James overcome those back problems.

Raimon is the reason James occasionally wears hats with a Navy SEALs logo during interviews, the crest with an eagle clutching a pistol and a trident acting as one of James' subtle messages he occasionally sends with clothing.

A post shared by Donnie Raimon (@donnieraimon) on Apr 16, 2017 at 3:08pm PDT

Raimon was a SEAL for 15 years and became a disciple of biomechanics when he used the science to help himself get over a severe neck injury suffered during a parachute jump that Navy doctors struggled to heal.

He purposely avoids the spotlight and doesn't do interviews. James generally doesn't speak about Raimon or his techniques, and he credits the Cavs training staff with working to keep him in the best shape.

"Between Donnie and Mike, it's a great one-two punch," James said.

Mike is Mike Mancias, who has been taking care of James' body since 2004 and is one of the most valued people in his circle. Mancias is in charge of much of James' recovery after games and practices. There are times when James works late into the night with Mancias and then starts again right after the crack of dawn, especially in the playoffs.

Much of Raimon's work with James happens before practices and games. Some of the work has gone viral in social media posts that show him putting James through ridiculous pregame paces using a physio ball. The results are on display in watching James' movements on the floor, where he looks as strong and fluid as ever.

In the 2014-15 season, James' first back in Cleveland, the back issues were weighing on James. The midseason injection helped, and he ended up carrying the Cavs to a gallant Finals loss to the Golden State Warriors. But it was evident in watching him at times that he wasn't quite himself. It was personified by at least one stat: dunks. James had a career-low 88 dunks that season, 46 fewer than the season before.

When James' summer workouts in 2015 were again slowed because of his back issues and he needed another injection in training camp that fall, James reached out to David Alexander, a Miami-based trainer with whom James had been working for several years. Alexander sent James one of his valued employees in Raimon. James eventually hired Raimon full time, and Raimon moved to live near him in Akron.

Raimon focused on strengthening James' core muscles and exercises that improved his posture, taking stress off the lower back. Before games, Raimon tries to activate James' core with intense work. Then, James will wrap himself in heat pads to stay warm, which he also does at halftime. Last season, James set a career high with 145 dunks. He is behind that pace this season, but he's making up for it in sheer power, as last week showed.

"LeBron is probably one of the best I've seen as far as just, every day you see him just doing stuff with Donnie every day," Cavs coach Ty Lue said. "He does a really good job of taking care of his body, and that's why he's able to play the way that he does."

Cavs officials and James himself will tell you there's no one reason James has been able to overcome the back issues. There's a team effort in taking care of James from a full staff of Cavs employees and doctors, plus his fastidious nature and physical gifts.

The Cavs have one of the largest player-support staffs in the NBA. In addition to Manicas, the team employs athletic trainer Steve Spiro, physical therapist George Sibel, strength and conditioning coach Derek Millender and performance specialists Yusuke Nakayama and Alex Moore, who contribute to James' care.

Raimon, though, is employed by James privately, and the Cavs grant him limited access. Often, James and Raimon have to do their work in the hallways in visiting arenas. When James went to play for the Heat, he had the same arrangement for Mancias, who would often treat James in the hallways before games. Mancias eventually was hired by the Heat. Mancias has worked for the Cavs during both of James' tenures.

Several NBA players have personal trainers who work with them during the season. Star players tend to get extended privileges. Michael Jordan famously worked with trainer Tim Grover. Kyrie Irving works with veteran trainer Robin Pound, who got some special access from the Cavs and has moved with Irving to Boston, where he now works in conjunction with the Celtics staff.

During last NFL season, the New England Patriots made headlines when coach Bill Belichick reportedly cut the access of Alex Guerrero, Tom Brady's longtime trainer. It can be a delicate balance to have a private trainer work with team staff, but James has navigated it successfully for years. The teams love the results and give James the latitude that few other players would be granted. The trust hasn't been abused, numerous sources said, even if it does create some awkward moments.

"It's every day. Around the clock every single day, working on my body," James said. "Either with treatment or working on my body in the weight room. Continuing just to build strength throughout the season when everybody else is kind of tearing down ... not putting too much pounding on my legs when I'm on the court, but being very efficient. I've kind of figured that out in my 15th season."

"James was having to lay on the court when resting during games. It brought back unsavory memories of Larry Bird and Steve Nash, players who had their careers derailed by back issues."

James is known to personally spend seven figures a year caring for his body, and Raimon is part of that tab. So are personal chefs and masseuses. He also gets private treatments with liquid nitrogen to help reduce inflammation. James' home facilities rival those of professional teams. In his home in Akron, James has a fully outfitted workout gym, hot and cold tubs and a hyperbaric chamber.

Ultimately, even with all the support, James feels like taking care of his body has been a personal journey he has had to figure out largely by feel and by mixing work with experimentation. The rewards he is seeing his season -- saying himself that he's aging like fine wine -- have allowed him to pause to evaluate the ongoing process.

"I just think over time you kind of learn how to grow with it and how to deal with it when certain situations happen," James said. "It's very challenging, and you just have to go through it, and there was never someone I could talk to when I was coming up that was a part of this league that I could kind of lean on. I've learned everything on the fly. And I'm not talking about the game. Obviously, I've had coaches, I've had teammates and things of that nature. But as far as being an NBA player, how to approach it, how your body and how you continue to stay consistent, I've learned all of that on my own."

ESPN's Dave McMenamin contributed to this story.