Gymnast Gabby Douglas was a darling of the 2012 London Games after winning gold in the women's all-around. Four years later, critics on social media have been particularly harsh. (Jayne Orenstein/The Washington Post)

As younger U.S. teammates added to their medal haul Sunday, Gabby Douglas, the Virginia Beach native who captivated the gymnastics world in winning all-around gold at the 2012 Olympics, struggled to a disappointing and emotional finish at the Rio Games.

After finishing seventh in a field of eight in her lone individual event, the uneven bars, Douglas fought back tears when reporters’ questions about her performance turned to questions about a wide range of criticism that has been directed at her, much of it on social media: about her stance during the playing of the national anthem, her expression in the stands as Simone Biles and Aly Raisman vied for all-around honors, and a perception that she has distanced herself from teammates.

Douglas said she had avoided the Internet while in Rio because of the “negativity,” which she said she didn’t understand.

“When they talk about my hair or me not putting my hand up on my heart or me being very salty in the stands, they’re really criticizing me, and it doesn’t really feel good,” Douglas said, her eyes tearing up. “It was a little bit hurtful.”

There are many ways gymnasts can medal at the Olympic games in Rio. Here's how the competition works. (Video: Jayne W. Orenstein/The Washington Post/Photo: Jonathan Newton/The Washington Post)

The exchange followed a memorable afternoon for Biles, 19, who won her third Olympic gold in as many events — becoming the United States’ first Olympic women’s vault champion. Her 0.713-point margin was staggering for gymnastics, and Biles earned it by performing two of the sport’s most difficult vaults, the Amanar and Chen, to finish with 15.966 points. Russia’s Maria Paseka took silver (15.253), and Switzerland’s Giulia Steingruber claimed bronze.

Biles was one of six U.S. gymnasts to compete Sunday, the first of three days of individual apparatus finals at 13,000-seat Rio Olympic Arena.

Madison Kocian, 19, took the silver medal on uneven bars, edged by Russia’s Aliya Mustafina by less than 0.100 points. And Alex Naddour, 25, of Gilbert, Ariz., became the first U.S. man to win an Olympic medal on pommel horse in 32 years with his bronze.

Biles, who had qualified for the vault final with the top qualifying score, was last to go, which gave her the benefit of knowing the mark to beat.

Unlike uneven bars, the vault isn’t for long, lithe body types or the tiny sparrows of the sport. It’s well-suited to the powerful, explosive Biles, who is 4 feet 9 of solid muscle.

For her first vault, she performed the 2½ -twisting Amanar, earning 15.900, by far the highest mark of the competition. She could have easily opted for a safer second vault but stuck with her plan of doing the more difficult Chen that she had spent the past eight months perfecting. She earned even higher marks for that.

Finishing fourth was India’s Dipa Karmakar, who like the 41-year-old Oksana Chusovitina competing for Uzbekistan, attempted the so-called “vault of death,” which demands 2½ somersaults. Neither landed it cleanly, but fans cheered the boldness of their attempt. Afterward, Chuovitina was honored with a video tribute to her seven Olympics, and she acknowledged the crowd by forming a heart with her hands and placing it on her chest.

The struggles Douglas endured, both on the arena floor and in the 20-minute exchange with reporters afterward, tugged at the heart as well.

The teenaged darling of the 2012 Games, Douglas joined an elite few in qualifying for a second U.S. Olympic gymnastics team at 20 — an extremely difficult feat, given the number of gyms around the country that churn out Olympic-caliber teens to supplant veterans every year.

In terms of physical maturation, the sweet spot for a female gymnast is brief. And given the pressure of training and intensity of competition, the burnout rate is high.

Douglas’s post-competition interview began in a cheerful tone, even as she acknowledged that she had come to Rio hoping to achieve more. While she contributed valuable skills to the U.S. team gold medal through her uneven-bars routine, Douglas had hoped to defend her 2012 all-around title.

But she qualified third, behind Biles and Raisman, and was barred from the all-around final by the Olympics’ two-per-country limit.

“You always want to picture yourself being on top and doing those routines and being amazing,” Douglas said. “I pictured it differently, but that’s okay because I’m just going to take this experience as a really good, positive one.”

The tenor of the interview changed when a reporter asked, “Do you think your Olympics got ruined?”

After a pause, Douglas said it had been “an amazing, crazy — also fun — experience.”

She was asked what she would have done differently at the Olympics, other than score higher. She looked puzzled, so the reporter recounted various criticism.

“Obviously I wanted to finish on a better bar routine,” Douglas said. Then she spoke of difficulties she had endured during these Games and apologized if her gestures or facial expressions had been misconstrued.

“Everything I’ve gone through has been a lot this time around,” Douglas said, “and I apologize if [I seemed] really mad in the stands. I wasn’t. I was supporting Aly. And I always will support them and respect them in everything they do. I never want anyone to take it as I was jealous or I wanted attention. Never. I support them, and I’m sorry that I wasn’t showing it.

“I’ve been through a lot,” she added. “I still love them. I still love the people who love me. Still love them who hate me. I’m just going to stand on that.”