Late 30's and can still run 2:30. If it means anything to her, she could be one heck of a masters runner and do well versus the open field too.
But age is a relentless competitor and you have to accept being slower.
For me it was age 40. My 10K dropped a minute Training hadn't changed. Most of my time trials and intervals were the same.
But in races, I just could not run as fast.