How Much Data Do You Need?
Credit: Photograph by Justin Steele

3. You're a Wannabe Pro
This is me. And if you, too, love beating last-year's time in your local trail run, ramping up for a triathlon, training for an open-water swim, you'll want to check out sports-focused body monitors, like those from Garmin and Polar, which now produce a mind-boggling range of features. Different models aimed at various sports mix and match from a laundry list of sensors that include GPS, heart-rate monitors, accelerometers, gyroscopes that measure force, and magnetometers that measure rotation. Onboard chips crunch the data to produce athletic metrics useful to everybody from mountain bikers to snowboarders to marathoners.

Endurance athletes have long used the hallmark metric of this category – heart rate – to establish so-called training zones, heart-rate brackets that produce different fitness effects, like expanding your aerobic capacity or building your tolerance for lactic acid.

The latest generation of these devices can do so much more than track heart rate: for instance, telling me how many strokes I've taken in one length of the pool (a measure of efficiency) and even my running metrics, like ground-contact time (the milliseconds my feet spend on the ground between strides).

"If you're implementing that data correctly, it can tell you a lot about your stride – if it's too long, too short, what your mechanics are like," says Devor. That's what helped me: After years of painful running injuries, I've found a Garmin watch that allows me to monitor – in real time – running metrics related to risk of injury, including stride cadence and average vertical oscillation, meaning how much I bounce up and down with each step. By working to improve each metric, I'm now running faster than ever, without pain. My pick is the the Garmin fenix 2. Suffice it to say you won't find it in my sock drawer any time soon.

Your Tracker: Garmin fenix 2

There's little the fenix 2 can't do to better your sport. Our two favorite features: It crunches numbers such as your height, weight, and pulse to tell you how well you've recovered since your last workout, and it can estimate your V02 max to predict your best possible time for any running distance.