Photo: Greg Broom

The Basics

Haven't smartphones made these irrelevant?

No. And the reasons extend beyond the annoyance of training with a phone strapped to your arm. Instant speed, altitude, and heart-rate data shrinks the feedback loop. With a purpose-built training watch, you can make constant adjustments to ensure you're hitting your targets. Slowing down every few minutes to check readouts on your phone or worse, waiting until you get home to download it, isn't the same. And if you're a swimmer, the waterproof thing matters. Every unit here is fully submersible.

How accurate are they?

These watches will all peg your location to within 10 feet — close enough to discern which side of the road you're running on. Improved software helps these devices figure out missed segments when buildings, tunnels, or other obstacles block your sky view. You're out of luck if you're underwater, though — getting a GPS signal below the surface just isn't physically possible.

Will these work with my heart-rate monitor?

As with any other wireless system, the answer is yes, as long as both devices speak the same language. Learn this term: ANT+ (pronounced "ant plus"). It's the most popular wireless protocol for athletic devices, due largely to the open alliance of manufacturers that back it, which guarantees broad interoperability. There are other formats out there, but the sports world seems to be converging on ANT+ for now.

Buying Advice

If you've never trained with a GPS watch, now is a great time to start. The hardware and software interfaces are remarkably refined. Even older GPS watches rarely break down; they might not be as accurate or full-featured as newer models, but if you already have a GPS watch that you're happy with, you might want to wait a couple of years. Next-gen models will likely connect to cell towers — letting friends track your progress online — and feature Bluetooth Low Energy, a new protocol that will allow these devices to talk to smartphones, which could usher in a new wave of training apps.