LEXINGTON, Ky. — From his lonely practice lane, a catwalk over a local gym and gymnastics facility, Dallas Robinson chases his dream of being an Olympic sprinter.

His 60-meter strip of artificial turf could not be more remote from the world of most elite sprinters, a world filled with big egos and endorsement contracts, where coaches fret over thousandths of a second and agents fret over millions of dollars.

And Robinson could hardly be more different from those sprinters. He is 6 feet 4 inches and runs remarkably fast despite being 210 pounds, roughly 40 more than many of the competitors he hopes to join at the Beijing Olympics this summer.

His dream sprang out of nowhere, prompting Robinson to quit a $100,000-a-year sales job so he could train. He left behind a comfortable, normal life for a job in a tire store, driven only by a nagging sense that this is what he is supposed to do.

“I believe I’m going to end up in the Olympics,” Robinson, 25, said. “I don’t know how I’m going to get there. But I guess if the mountain were smooth, you wouldn’t be able to climb it.”