Dr Alexis Colvin talks about the benefits of lightweight marathon blankets

Sixty-five volunteers for New York Road Runners gathered early Sunday on the west side of Central Park to tackle an unusual job: stripping 52,000 metalized blankets from industrial-size rolls several hours before the start of the New York City Marathon.

Piles of the blankets soon formed large, shimmering shrubs on the side of the road, about 100 yards beyond the finish line, where they awaited the sweat-soaked masses.

“They’ve really become part of the mystique,” said Lee Troop, an elite-level coach.

Heatsheets, as the branded blankets are known, have become synonymous with the marathon. Designed to help ward off hypothermia, the blankets are as much marketing vehicle as medical device. This year’s version, which measured roughly 6 feet by 4 feet and weighed three ounces, featured advertisements for United Airlines, Foot Locker and Tata Consultancy Services, the marathon’s title sponsor.