The finish line is above 10,000 feet. I’m gasping for air. Tunnel vision. End in site. Finish line approaching. Gotta puke. . . oh, no. Slight deviation from plans!

How had things gone so suddenly awry? The first 13.1 miles of the Vail Pass Half Marathon at the Teva Mountain Games had been such sheer pleasure. The climb was steep, yes, but my pace seemed perfect and my company, a friendly runner who matched my speed until the altitude got the best of him at mile 8, made the time whisk by.

The sky was blue. Sunlight filtered through spring green aspens, and distance passed quickly and easily even with the continuous, grinding climb up 2,900 feet.

The organizers of this “half marathon,” however, had stitched an extra .6 miles at the end. I assume this was to bring the finish line to an accessible parking area. So as I crossed the 13.1 mile sign, I kicked hard. The slope rose up in front of me as I accelerated to give it all I had left.

I closed on the finish line with tunnel-vision creeping in from the edges, lunged the last few feet, staggered three steps and hurled what little water was left in my stomach onto the gravel. I guess the altitude really did get the best of me!

The leaders had finished the race fast. Colorado-based Glenn Randall, the 2010 winner of the Pikes Peak Ascent, won this half marathon for the men with a time of 1:23:23. Morgan Arritola from Ketchum, Idaho, a Nordic skier who raced in the 2010 Vancouver Olympics, finished first in the women’s race at 1:37:44.

It was a tough run. But I felt good about my finish of 1:58:02, which put me at 28th overall. As my first half-marathon, I found the event well organized, fun and beautiful. I’m not so sure about that extra “bonus” .6 miles at the end, though.

—Contributing editor Sean McCoy is based in Denver.