TOKYO — Allyson Felix stayed on the track for a long time on Friday night after finishing the 400-meter race.

She fell on her back after peering up at the scoreboard and seeing her name behind those of Shaunae Miller-Uibo of the Bahamas and Marileidy Paulino of the Dominican Republic.

Allyson Felix, Lane 9, third place, 49.46.

She had done it. Ten Olympic medals.

When asked if her reaction — lying on the track, staring at the sky — was exhaustion or emotion, she said it was “probably a combination.”

She has competed in so many 400-meter races in so many places over so many years. It always hurts, she said. On Friday, the pain was diluted by joy.

She had tied Carl Lewis as the most decorated American athlete in track and field. She had run her second fastest time ever, faster than her silver medal performance at the 2016 Olympics in Rio de Janeiro.

And she had done so on her terms: as a mother, an activist and an entrepreneur.

Coming into these Games, with nine Olympic medals (six golds and three silvers), Felix was already tied with the Jamaican sprinter Merlene Ottey as the most decorated female Olympian in track and field. She also has 18 world championship medals, including 13 golds.

But this Olympic berth — her fifth — meant something else altogether.

“This one is just so different,” she said, her first bronze medal around her neck. “It’s hard to describe because I feel like all the other ones, I was just really so focused on the performance. And this one, it’s so much bigger than that.”

She had heard the doubters, the skeptics. A 35-year-old couldn’t come back from an emergency cesarean section and regain championship form. And to think she could qualify for the U.S. Olympic team again? That she would even consider herself a medal contender at the 2020 Games?

Even her placement on the track, all the way out in Lane 9, as one of the slower automatic qualifiers out of the semifinals, was an indication of her underdog status.

“Nobody thought I was going to be here,” she said, making exceptions for her family and her coach, Bobby Kersee. “I’m a fighter. The last couple of years, it’s what I’ve done. I just needed a chance.”

And as she fought for more chances for herself, she flung the doors open for future generations of female athletes.

After giving birth to her daughter at 32 weeks, she shared her story widely, visiting Congress to discuss racial disparities in maternal mortality. She called out Nike for the way in which it treated pregnant athletes, and pushed for brands to provide protections for those looking to start families.

She came to these Games sponsored by Athleta and wearing spikes from Saysh, a company she launched weeks before the Games. Her final races at the Olympics have been run quite literally in her own shoes.

And she came to Tokyo supporting fellow Olympian mothers, having recently announced a partnership with Athleta and the Women’s Sports Foundation that will provide grants to female athletes with children. The grant has already been awarded to Gwen Berry, a hammer thrower, and Aliphine Tuliamuk, an American marathon runner.

“Obviously, we’re working to change industry standards,” Felix said. “Hopefully I’ve brought some attention to those things. That’s what I’ve tried to do.”

As she described her ongoing advocacy, she was interrupted by the Jamaican women’s 4x100-meter relay team. They had just won gold. But they wanted to see Felix and celebrate her, too.

It took a lot to get here, Felix said, beaming as she described a FaceTime conversation with her daughter, Cammy, shortly after the race. Cammy is starting to get the whole running thing: “Momma’s at work,” or “Momma’s running.” As Felix FaceTimed her family, she realized that her daughter should have been asleep. “We’ll deal with that later,” she said.

Before the race, she said, she had contemplated what she would tell her daughter about the Olympics whenever she is old enough to understand.

“The biggest thing I want her to know is when you go out and you do something, you do it with character and you do it with integrity, and you do it to the best of your ability,” she said. “That’s all anybody can ask of you. And if you do that, you’re proud of that and that’s enough.”

She can’t wait to get home, and is counting down the days until she can see her family again.

But Felix may have one more race in her. She is expected to join the U.S. 4x400-meter relay on Saturday and perhaps add one more medal to the collection.

But on Friday night, she focused on enjoying her accomplishment. She had come back for another Olympic cycle in exactly the way she wanted.

Gone were the days when anything other than a gold medal brought tears and disappointment.

“I was thinking about this before,” she said, smiling. “It’s really hard for me when I don’t win to still have joy.

“Tonight, I have joy.”