Her last recorded split was 33:32 at 10K.

Eight days shy of her 40th birthday, Keira D’Amato, the former American record holder in the marathon and the half marathon, dropped out of the Chicago Marathon after the 10K mark. She had talked before the race about running the American record.

On the marathon broadcast, her coach, Ed Eyestone, said D’Amato had developed some arch pain during her taper. Her last recorded split was 33:32 at 10K. After the race, he clarified in a text message to Runner’s World that the pain was in her left foot and said she would have imaging done when she returns to Utah.

D’Amato ran 2:19:12 in Houston in 2022, breaking the American record that had stood for almost 16 years. In 2023, she ran the American record in the half marathon, 1:06:39. (Both records have since been broken.)

But in the most important race of the past four years, the 2024 Olympic Marathon Trials in February in Orlando, D’Amato struggled in the heat and dropped out at mile 20.

This summer, she overhauled her training: She made a coaching change, and she moved from her home in Richmond, Virginia, to Park City, Utah, to train at altitude for the first time under veteran coach Eyestone.

In the days before the race, D’Amato told Runner’s World that her training had gone well, but she didn’t know what to expect, given her inexperience with altitude. Runners’ times during workouts are generally slower at higher elevations than they are at sea level, so she couldn’t use those workouts to predict her performance.

Today, on the flat streets of Chicago, an injury got to her before she could find her answer.

Eyestone is undeterred: “She will live to fight again!” he wrote.