In 2007, Bruce Jenner (center) posed with former U.S. Olympic athletes Gary Visconti (left) and Peter Vidmar before a news conference in support of Los Angeles' bid to host the 2016 Summer Olympics. Reuters

Long before he was known as the stepfather of reality-television star Kim Kardashian, the stepfather-in-law of hip-hop lightning rod Kanye West or even the husband of Kris Jenner, Bruce Jenner was among the most beloved amd celebrated athletes in America. Overlooking his athletic achievements may appear understandable given his ubiquity outside sports in recent months.

Almost four decades ago, Jenner became a household name as a U.S. gold-medal decathlete at the 1976 Summer Olympics in Montreal. His rise to athletic glory was a compelling story about triumphing over long odds, and his single-handed role in returning America to prominence in a sport it once dominated captivated the country. But Jenner’s role in popular culture in the 1970s sharply contrasts with his current public image as a prominent figure on the E Network reality-TV show “Keeping Up with the Kardashians.” Once an amateur athlete who graced the cover of Sports Illustrated, Jenner is now a familiar presence on covers of US Weekly.

Even the recent developments associate with Jenner’s possible transition from a male to a female, as evident through tabloid photographs of his altered appearance and vague confirmations by members of his family, have spotlighted his changing role in the view of mainstream America.

An exclusive interview with ABC News’ Diane Sawyer in May, and a possible docuseries on E reportedly await Jenner and his growing celebrity status. The increased name recognition could mean the 65-year-old will have the opportunity to serve as a high-profile figure for transgender issues in America at a critical point in the lesbian, gay, bisexual and transgender community’s fight for equal rights. There have been other celebrities who have transitioned from one sex to another, but none as famous as Jenner.

It has been a fascinating journey for Jenner, with almost all of it based on the events over a 48-hour period in Montreal. In a true underdog story, Jenner would go on to set a world record after dedicating several years to accomplishing a highly difficult feat.

“Bruce’s story was, he picked up and left home, left Iowa, and really self-coached himself,” American Dan O’Brien, the 1996 Olympic gold-medal decathlete, told International Business Times. In the 20 years since the Montreal competition, no American had claimed Olympic decathlon gold until O’Brien came along.

“And that’s really shocking to me,” O’Brien said. “To think that a guy got to that level by just ham-and-egging it, just working a little with this guy, working a little bit with somebody else, going to San Jose for a month, and then going back to Santa Barbara. That’s a very difficult thing to do in this event.”

Jenner’s life story from his childhood days to his Olympian years was straight out of Hollywood lore. A native of Mount Kisco, New York, he suffered with dyslexia as a child, when he was ridiculed by his peers. However, Jenner found confidence in sports, trouncing anyone who made fun of his learning disability.

He earned a football scholarship to little-known Graceland University in Lamoni, Iowa, where the track coach encouraged him to compete in the decathlon, a grueling 10-event gauntlet.

Unranked and relatively unknown, he would then head to Eugene, Oregon, to train for the 1972 Summer Olympics in Munich. Although a long shot, he managed to earn a spot on the U.S. team by setting a personal best in the final event: the 1,500 meters. He would finish 10th out of 34 in Munich, and use the letdown as a springboard to reach new heights. No American would earn a medal in the decathlon in 1972, and Bill Toomey’s gold in 1968 was the only medal the U.S. could boast in the event since Rafer Johnson in 1960. It was a far cry from the American team that had won six consecutive golds between 1932 and 1960, medaling 12 times overall during the same period.

Virtually obsessed, and possessing a hypercompetitive nature, Jenner trained on a reported shoestring budget of $9,000, which was obtained by selling insurance part-time. He set up a hurdle in his tiny apartment to continue a home-training regimen that already included between six and eight hours of work a day.

The hard work and determination would pay off, and Jenner earned his gold four years later in the decathlon, a competition so demanding that its winner is often dubbed the World’s Greatest Athlete. To an extent, Jenner also played a critical role in the athletic proxy wars of the Cold War, securing the decathlon’s top prize for the U.S. in 1976 after the Soviet Union had taken both gold and silver in 1972, as he finished well ahead of the Soviet bronze medalist Mykola Avilov.

Jenner has said many times he knew immediately after the victory that his athletic career was over. He famously left his pole-vaulting equipment at Montreal’s Olympic Stadium, with his future in doubt after achieving his ultimate goal.

“I had no plans, nothing,” Jenner told the New York Times in 2008.

However, he did have access to a friend’s hotel suite. “So there I was in this amazing suite, just beautiful, and I’m looking around, and there’s this piano -- the place had a grand piano -- and I thought, ‘Huh, maybe I should learn to play the piano.’ I mean, I was extremely satisfied [with his Olympic win], but also devastated by the finality of it all.”

There wasn’t a future in athletics or a career as a concert pianist, but, unlike a sizable number of Olympic champions, Jenner found a way to parlay his greatest athletic accomplishment into so much more.

Jenner banked the 1976 success in numerous ways. He would appear on the iconic Wheaties cereal box, land television and movie roles, and embark on a lucrative motivational speaking tour. He also earned corporate-representative gigs for powerful brands such as the credit-card giant Visa, with such jobs continuing to roll in more than a decade after Montreal.

In 2002, Jenner told Sports Illustrated just how much he’s relied on his singular Olympic accomplishment.

“Nobody’s worked one performance better than I have,” Jenner said in the wide-ranging profile. “I was in that stadium for 48 hours, and now you can’t get rid of me.”

Decades removed from one of the greatest Olympic performances in history, Jenner’s list of accomplishments plays out more like that of a hyperactive Renaissance man than an athlete stuck in neutral after he realizes the mortality of his superhuman abilities.

Jenner’s post-Olympic career became the benchmark: piles of cash, fame and respect from adoring fans.

Very few Olympic athletes since have replicated the same luxuries and status.

O’Brien set records in the U.S. and world championships, yet failed to qualify for the 1992 Summer Olympics in Barcelona. It was Dave Johnson, O’Brien’s partner in Reebok advertisements in the early 1990s, who would earn a bronze in Barcelona. It was the lone U.S. medal in the competition since Jenner’s in 1976.

O’Brien said he felt content with his success to that point, although Jenner made sure to remind him that greater feats lay ahead.

“There was a time in my career, when I failed to make the [’92] team, [but] I was happy to be the world-record holder, I was happy to be America’s best guy,” O’Brien said. “But Bruce never let me forget that I didn’t have that one thing: the Olympic gold medal. In a contradictory kind of way, he motivated me to get the one thing I was missing, and that was the gold.”

Then came the 1996 Summer Olympics in Atlanta. O’Brien would beat Germany’s Frank Busemann by 118 total points, and further endorsements and opportunities would follow.

But O’Brien never came close to replicating Jenner’s success outside the stadium.

“You dream about doing it like Bruce Jenner: You come out of the Olympics, sign on the dotted line for $10 million and never have to run on the track again,” O’Brien told Newsweek in 1997. “Nobody’s all over the place like Jenner was, except maybe Tiger Woods -- and he wasn’t even in Atlanta.”

Indeed, it’s difficult to find an athlete who won one gold medal and did more with it than Jenner. Legendary swimmer Michael Phelps landed numerous endorsement deals, but that’s been due to 18 gold medals between 2004 and 2012.

Since the days of O’Brien, the U.S. has won the decathlon in the past two Olympics: Brian Clay in Beijing 2008, and Ashton Eaton in London 2012. Neither is a household name nor do they figure to be, in perhaps a clear indication of how the decathlon is no longer a springboard for post-Olympic success. Eaton is the current world-record holder, yet it would be difficult for the average American sports fan to recognize his name, let alone pick his face out of a crowd.

O’Brien fondly remembers his time with Jenner, describing him as “an inspiration.” He recalled the last the time they saw each other in 2012, when Jenner returned to Eugene for the Olympic trials and was in the process of filming “Kardashians.”

“Bruce was the happiest I’d ever seen him,” O’Brien said. “He was always upbeat. That’s what I love about Bruce. He always seemed extremely confident and happy to me.”

Changes in Jenner’s appearance in recent months have surprised a lot of people, including O’Brien. He now finds Jenner unrecognizable.

“Bruce and I, we got a chance to hang out in the 1990s, and I’d see him from time to time. We’re very friendly. But we didn’t stay in touch, we weren’t close. So, when I see all this happening, it’s like I don’t even know who that guy is.”

Bobby Ilich contributed to this report.