BRECKENRIDGE, Colo. — It’s 6 a.m. on a January day, dark as night, and a handful of local athletes are skiing as fast as they can — uphill.

Each of the 31 participants is wearing a headlamp, and nearly all of them are wearing skis that weigh less than an average pair of hiking boots. One of them is Sharon Crawford.

Crawford, 75, who lives in Frisco, Colo., about 10 miles away, is no stranger to uphill ski racing. In fact, she is no stranger to any type of race that involves strain, endurance or pushing one’s body to the limit.

This event, a part of the Breckenridge Ascent Series, took Crawford from the base of the Breckenridge Ski Resort, which has an elevation of 9,600 feet, up a black-rated trail for nearly two miles and more than 1,500 vertical feet. The fastest racer, Jill Sorensen, knocked it out in 32 minutes. Crawford clocked in at 1 hour 2 minutes.