It's fair to say that, while it's not yet for sale, The Apple Watch is the fitness tracker to beat. For athletes, the device's capabilities are on par with the best trackers: It can monitor pulse and heart rate as well as steps, distance, and calories, and talk to your iPhone. Downsides include the need for a phone to function — a burden for most — and it's not waterproof, so it isn't your best choice for the pool.
But the biggest advantage of the Apple Watch is that it's built by Apple, which plans to leverage its App store — as well as the company's new hires like Ravi Narasimhan, former vice president of biosensor-maker Vital Connect — to turn those sensors into devices that could theoretically measure blood glucose levels, body temperature, or hydration levels. For now, it remains the most talked about tracker there is, if for the design, Apple fan hype, and perceived potential.
[Coming Early 2015, apple.com]