As a decorated college runner at Notre Dame and then at the University of Tennessee, Dylan Jacobs dabbled with a device that many of his teammates considered indispensable.
But on those rare occasions when Jacobs succumbed to peer pressure and slapped a GPS watch around his wrist, he almost immediately remembered why he had resisted the temptation in the first place.
“The runs just felt so much longer,” said Jacobs, 23, a three-time N.C.A.A. champion who recently turned pro. “That was one of my main problems with it. I wasn’t enjoying myself or looking around.