To become really useful (and hence marketable), GPS watches had to first become, well, watchlike. That point was finally reached around 2010, and as of 2012, you could buy a GPS watch the same size, shape and general style as any other fashion watch on the market. Some models, such as a 13-millimeter (0.51-inch) thick prototype released in February 2012 by Epson, were actually smaller than many non-GPS sports watches [source: Tucker].
Small size does not mean a small number of features, though, and here's where GPS watches really became useful training tools. Knowing exactly where you are at any given moment is nice, but unless you're in the middle of nowhere or trying to choose a club in the middle of an unknown fairway, the application is limited. GPS watch manufacturers saw this, and expanded their products' versatility by adding in features from other sports devices such as bike computers, pedometers and heart rate monitors.
Many GPS watches can sync with other devices using wireless signals, such as ANT+, a small, energy-efficient system. These additional devices often measure biometrics: bodily systems measurements such as heart rate, which athletes can use to gauge the intensity of their workouts. Other sensors included with GPS watches may include shoe-mounted cadence monitors that track the rate of a runner's stride and bike-mounted sensors that detect wheel speed and the force that a rider is exerting through the pedals. Computer software that comes with these watches lets users download array of workout data collected by the watch either wirelessly or through a USB port. By entering basic information such as height, weight and age into the watch, the tech-savvy athlete can have a precise, sport-specific tool, a 21st-century version of the athlete's training diary.
This combination of location and biometric data is the meat of what makes a GPS watch worth the expense. But as in many tech-device scenarios, it's easy to get overwhelmed by the options available. GPS watch prices vary, but with prices in early 2012 ranging from $100 to more than $400 for various models, they're still not a small expense. How can you choose the most appropriate GPS watch for your needs?