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This article was originally published in Trail Runner Magazine in September, 2002.
For some, the allure of trail running is getting away from controlled distances, pace and calories burned. Trail running is about adventure, exploration and purity, not obsession of gadgetry. But once in a while, curiosity strikes, and knowing the details of your run can both entertain and help you gauge your training. Being aware of how many calories you’ve burned, for example, can help ensure that you’re putting enough fuel in your body to stay strong.
Here’s the low-down on a few devices that measure distance traveled, pace, time and calorie output, among other sometimes-helpful features.
Timex Ironman Speed + Distance System
The “wow factor” of this device is hard to beat. A sleek Global Positioning System (GPS) receiver (attached to your upper arm with an elastic band) links to a wrist instrument that looks like an ordinary sports watch. In fact, the watch itself has all the features of a regular Timex Ironman watch (clock, timer, alarm, etc.), while the GPS system allows you to track your mileage with atomic-clock (really) accuracy. The satellite tracking is accurate to 1/1000 of a mile. Flipping through the manual for about two minutes can tell you everything you need to track your running progress, and the watch display is easy to read and understand.
The downsides are that the receiver unit is a bit bulky (about the size of a deck of cards, though lighter), and “fatal GPS errors” can occur as the batteries run low (after approximately eight to 10 hours). The lack of an altimeter helps keep the interface simple, but it would be a nice feature, especially since the device could supply very accurate readings.
Weight: GPS monitor: 6.2 oz., watch: 1.8 oz.; MSRP: $200 (for 50-lap model); www.timex.com
Freestyle’s digital pedometer, the Tracer, calculates distance covered by measuring foot strike and accumulating total distance based on the length of your stride. No visits to the track are necessary; the instructions suggest taking 12 steps, measuring the distance and dividing by 12 to calculate personal stride. But since step lengths can vary on trails, the accuracy of the Tracer can’t be exact; the more smooth the trail, or the more your step-lengths average out between the up- and downhills, the more accurate the Tracer will be.
The pedometer is clipped to your shorts or hydration belt (as close to your hips as possible), and although the stride-counter makes a slight noise with each bounce, the small profile of the Tracer is relatively unobtrusive.
Other features include a step counter, clock and calorie counter (estimation only) based on the number of steps taken and your body weight. The digital display is easy to read after you run, or if you remove the device from your waist. Trying to read data while the Tracer is on your waist belt could land you a lot closer to the trail than you’d like.
Weight: 0.9 oz.; MSRP: $25; www.freestyle.com
Nike SDM Tailwind
Instead of measuring each step taken, the SDM (Speed and Distance Monitor) Tailwind uses a patented “speed sensor” technology to measure speed and distance. The speed sensor is an accelerometer (used in car alarms and airbags) that works by measuring the acceleration and declaration of your foot hundreds of times each second, recreating the actual motion of the foot through each stride. This technology proved extremely accurate. The orb-shaped SDM Tailwind is about three inches long, and clips onto your shoelaces. Initial thoughts of dead weight on the top of our feet dissipated, as the shape and weight of the Tailwind made it minimally obtrusive.
The Tailwind is the most intuitive measuring unit we tried, with just two function buttons that alternate between modes. It measures calories burned (based on gender, weight and age), distance speed, average pace and distance covered. The distance feature is handy for logging total miles over a period of time, and can be zeroed out whenever you want to start fresh.
Weight: 1.8 oz,; MSRP: $125; www.nike.com