Part of the problem was that Webb did enough to make the extraordinary look altogether attainable. In July 2007, at an otherwise subdued meet in Belgium, a series of pacesetters guided Webb through the opening laps of the mile before he was left on his own, his stride somehow lengthening as his closed on the finish line. His time, 3:46.91, broke Steve Scott’s 25-year-old American record by almost eight-tenths of a second.

In an interview afterward, Webb sounded euphoric — not necessarily because of what he had accomplished, but because of what he believed was still possible. He was convinced that he could run even faster. It was his modus operandi: anticipating rather than reflecting. Besides, he was only 24.

“I bet if you asked a lot of people about the races when they ran their best, it always kind of feels that way,” Webb said. “It felt incredible.”

Yet it was also the start of a slow decline. Two weeks later, Webb injured his hamstring, which hindered him at the world championships. Over the coming months, with the 2008 Olympics not far off, Webb continued to train the only way he knew how: white hot. He hit the weight room particularly hard.

“I wanted more, more, more, more, more,” Webb said.

It turned out to be too much. He was left off the Olympic team after placing fifth at the United States trials.

When he was in the thick of his career, Webb avoided watching video clips of his races, especially the good ones. He thought nostalgia would breed complacency, and nothing had the potential to make him more nostalgic than his American record. “I didn’t want that to be the end,” he said.

So it was only in recent months that Webb was able to take a hard look at the race and come to terms with the physiological damage that the record probably caused.