Ski braggarts beware. A company called MapTrek can now confirm whether tales of heroic speeds and vertical feet are fact or fiction. The firm rents armbands with tiny global-positioning satellite transmitters that record a skier's location every five seconds. When you return the device, the data is downloaded and printed onto a map with "electronic breadcrumbs"
retracing your every move. The map charts miles traveled and vertical feet skied, and is even color-coded for speed. MapTrek plans to add head-mounted video cameras so skiers can star in their own action films. Resorts are itching to wire skiers to study traffic patterns, while parents and backcountry adventurers like the idea of a homing device. Founder James Gibson has mapped out Vail, Copper Mountain, Colo., and Sierra-at-Tahoe, Calif., among other resorts. The cost is about $35 per day. The GPS armband may be to skiing what a mirror is to aging. "Skiers have a great self-image of racing down a slope at 50 mph," Gibson says. "They may be surprised when they hold the truth in their hands."