KANSAS CITY • At a training session ahead of the United States Gymnastics Championships, Simone Biles wore a leotard with a bedazzled goat on the back.

It was a reminder, in case people somehow forgot, that she is the greatest American gymnast of all time.

With a combined 25 world championship and Olympic medals, including 18 golds, Biles stands alone atop the medal standings.

The 22-year-old got to this point by fearlessly performing elements that no one else has dared go near, and as she began her quest on Friday night for a record-tying sixth national title, Biles became the first woman to perform a triple double (two flips with three twists) in a floor exercise competition.

Although she had trouble on the landing and had to steady herself by putting both hands on the mat, the judges ruled she had completed the element, awarding her 14.35 points for the routine, the highest total for the floor exercise.

Of the wobble, Biles, ever the perfectionist, revealed she had too much adrenaline flowing to control her power on the triple double.

"It's such a hard skill that I shouldn't be mad," she said, "but I'm so mad about it because in training I've never done it before."

It was the third time in her career that Biles had introduced a new element to women's gymnastics.

She tried another novelty later that evening, a double-double dismount off the balance beam, and landed it with a slight hop.

Although the dismount was not as big a breakthrough as the triple double, it was another first.

"I feel like you should never settle just because you are winning or you are at the top," Biles said. "You should always push yourself."

The triple double is a skill that, until this point, had been done only by the men and it is still a rare feat.

None of the men at the national championships are expected to try one and most of Biles' competitors cannot even do a double-double.

"If you had told me 10 years ago that someone would be doing that, I'd be like, 'That seems a little hard and dangerous. I don't know,' " Nastia Liukin, the 2008 Olympic all-around champion and NBC Sports analyst, said. "Of course, if anyone can do it, it's obviously her."

When Biles' coach, Laurent Landi, approached her about working on the triple double last year, she had her doubts.

She played around with the skill a few years ago, but only in a foam pit, which protected her from getting hurt if she messed up.

"My first reaction is no," Biles said. "Then he has to push me towards it until I'm ready to do it myself, and I'm like, 'OK, it's really not that bad.' He almost makes the impossible possible sometimes, and I don't know how he does it."

Now Biles has such a command of the move that she often bounces out of the landing, a sign that she has more than enough power to complete it.

After taking nearly two years off from competition after the 2016 Olympics in Rio de Janeiro, where she won the all-around title, Biles has been as dominant as ever, winning six medals, four of them gold, at last year's world championships.

Much has changed, though, within the US national team.

Biles is one of its oldest members, the designated leader of the team and an important example to the younger gymnasts.

She is also the only remaining member of the Rio Games team and the only active elite gymnast who has publicly identified herself as a survivor of the sexual abuse perpetrated by Lawrence Nassar, the national team's former doctor.

Although she is still figuring out how and when to best use her voice, Biles has always led by example and she remains at the vanguard of her sport.

If she completes the triple double at the world championships in Stuttgart in October, the trick will be forever known as the Biles II.

Two previous innovations - a floor exercise pass that succeeded at the worlds in 2013 and a vault she landed last year - are simply called the Biles because each was her first addition to a particular event.

The double-double dismount from the balance beam will also be called the Biles if she makes it in Germany.

"They are being pushed by Simone," Tom Forster, the performance director for the US national women's team, said of her competitors.

"Let's be honest. Everyone is trying to keep up."

NYTIMES