Also akin to NikeFuel, WillPower is only effective if you buy into it. WillPower takes into account how long you worked out, your gender, height, weight, and heart rate, giving you a score between 1 and 10. Personally, I only got as high as the 5.5 mark, so I probably wasn't pushing myself very hard, but I'd like a more meaningful metric.
What's more, since it lacks an accelerometer, one thing the device doesn't track is the number of steps you take during your exercise session. While running isn't the only workout routine that I do, it's the activity I did the most during my review period. In addition to the other information, I would have liked to know how far I traveled, but the gizmo doesn't have a GPS sensor, either.
I applaud Under Armour for how user-friendly its Armour39 app is. Once it loads, you just set up your profile, input a few key stats like weight and height, and you're off. You can sync the app to the fitness tracker; view a calendar of past sessions, where you can review stats and take notes; and access a settings menu to mess with the profile and device info. In addition, there's an assessment mode that involves running at various speeds for about 10 minutes, which allows the system to record your progress over the long term (the intention is for you to do an assessment once a month).
You don't need to have your iOS device with you to use the Armour39 -- the bug will sync once you're back in range -- but it's a lot handier to keep it around. If your iPhone is near, for example, you can get a breakdown of heart rate and intensity by regular intervals.
That's great, but there was one instance in which I left my iPhone in the locker after starting my workout, only to return and find that the app had restarted and my session was lost. It happened only once, but my confidence in the Armour39's ability to keep my workouts straight was shaken. The company said that it has not been a widespread problem, but it is looking at customer feedback and any other issues.
Also, the Armour39 app unfortunately is available only on iOS for the time being. The company plans to release an Android version, but it doesn't know exactly when.
For those who don't have an iOS device and can't wait, Under Armour will offer a watch accessory for $199.99 that syncs with the device and displays exercise stats in real time. The watch, however, is also unavailable, and the company doesn't know when it will sell that device, either.
The sole reliance on the app -- while solid -- is also a bit of a weakness. There's no Web site with more comprehensive stats and data, something I appreciated with Nike and Fitbit. Also, there isn't much of a social element, and you can't share your progress with friends and family against whom you may be competing. It was the social element that I found motivated me the most with some of the fitness gear.
Armour39 occupies its own place in the universe of fitness trackers. Rather than a casual device, Under Armour has gone after hard-core athletes with its system. Still, at $149.99, the Armour39 is priced the same as the FuelBand, close to the $129.99 Jawbone Up, and a good bit more than the $99.95 Fitbit Flex, which offers the most bang for your buck.