Women's 1,500 field one of the deepest at trials

— -- EUGENE, Ore. -- During a 20-minute period on the track, the country's best female middle-distance runners raced to get from the first round to the semifinals in the 1,500-meter event at the U.S. Olympic track and field trials.

The competitors spanned three decades in age and life experience over the three heats, making it one of the deepest pools of athletes fighting to make the Olympic roster.

And while the representatives in most sports at next month's Rio Olympics will be similar in age and experience, the 1,500 -- at least in the early rounds of the trials -- offers up a smorgasbord of athletes.

There were current college students, recent college graduates and one runner who skipped collegiate running all together, a mother who gave birth four months ago and two high school students, an American record-holder and others who barely got into this event.

In the first heat, 16-year-old Kate Murphy and 19-year-old Christina Aragon lined up alongside Sarah Brown, who gave birth to her daughter, Abigail, four months ago. Later, two-time Olympian Jenny Simpson and American record-holder Shannon Rowbury lined up against 20-year-old wunderkind Mary Cain.

Rowbury said it's an interesting race because it incorporates aspects of speed, quickness and endurance. And while many middle distance and distance runners peak in their late 20s and early 30s, younger or older athletes might excel in one of those skill sets and still be able to compete at the top level.

Rowbury needs to look no further than her own career: "I made my first Olympic team at 23 and I set the American record at 30," she said.

And Rowbury knows she wasn't the same athlete or person at 23 as she was 30. But athletes aren't concerned with the ages of their competitors - to them, it doesn't matter on the track.

Brown, who failed to qualify for the semis, spent her post-race interview partially in tears as she discussed how much it meant to just be back out on the track, racing again so quickly after giving birth and how it was a win for herself and her daughter.

"Seeing it through, for her, meant a lot to me," she said. "The best moment of this will be going out there and seeing her."

That reflective tone was nowhere near Aragon's interviews, which were best-described as bubbly. She talked about how she spent most of the winter competing in high school gymnastics and moved over to track after gymnastic regionals in April.

She said getting her race number was one of the most surreal moments of the trials, which, to runners like Brown and Simpson, is old hat by now.

"That was pretty cool -- the iron on bib? I don't even know if this thing comes off," she said.

Cain, often referenced as the future of American middle distance running despite her recent results, was comfortable in front of the media, making jokes and even signing an autograph for a fan who had made his way to the interview area. After five minutes, she dismissed herself, explaining that everyone knows she could talk forever if she allowed herself.

But when it came to Murphy, a handler shuffled her off, explaining she couldn't do any more interviews. She was too young to do too many, he explained.

Now, the runners will head back to their own space -- whether that be to their parents, spouses or friends. For the next 24 hours, they get to be who they are. But come 5:03 p.m. on Friday, all 24 runners will get back to the track. Their ages will be just a number, and their experiences will be nothing other than what got them to that point. And when the gun goes off, they will be just runners racing for three coveted spots.