"In 1990, she set the record, and then back in '91, she broke her own record, which was held for many many years," said Dr. Tris Carta, the Road Race committee president.
Her times are still the second- and third-fastest for women in MRR history. And despite her lack of training in years, she's proud of that.
"I feel a lot of pride in having run the second fastest time on a course that I know there was a lot of amazing runners who also ran on," O'Brien said.
These days, O'Brien is a different type of champion. She's a classically-trained violinist, and teaches students.
"I have a private violin studio with 30, 40 students. I teach at a private school -- I'm the orchestra director. I plan in a band so it's, like, all music," she said of how she spends her time. She's also a wife and a mother.
Now, you may think she picked up the string instrument when she finished competitive running, but it's actually the other way around. And the two are connected in her mind.
According to O'Brien, "I started violin when I was 8 and I learned the discipline of practicing because you really have to practice to master any instrument. And I think, you know, when I started running and basically training, that's what makes a good athlete is the training."
Being a musician and an athlete was a natural match. "So I think I had that understanding of you have to put the time into it to do it well."
Now she gets to see the next generation of runners, this time as the 2016 Manchester Road Race honorary chair.
"To be able to come back to such a special race and important race in my running career--it's feels great."