This data, along with some other general information about you, helps the app generate a profile that will be used to measure your WILLpower. Under Armour's WILLpower is a proprietary measurement, like Fuel points, of your overall effort. Your heart rate and the duration of your workout both influence your score, but so too does the position of your body. WILLpower is awarded on a scale of zero to 10, with it becoming increasingly harder to rack up points as you climb higher. So, you'll hit 3.5 pretty quickly, but getting to nine is going to be a pain. (Literally, you're probably going to be in pain if you push hard enough to be awarded nine WILLpower points.)
There's not much else to the app, however. You take the assessment, then start working out. You can set a WILLpower target, but that's about it as far as advanced features go. At the end of your session you're presented with a workout summary that gives you not just a WILLpower score, but also your average and peak heart rate, your average intensity, duration of your workout and the number of calories burned. Additional tabs break down your heart rate and intensity over time in bar graph form. The data is great for number nerds, but there isn't much you can do with it. Armour39 has no social aspects and, despite your workouts being synced online, there is no robust web app for digging deeper into your results. In fact, you can't even just use the app to quickly check your resting heart rate or delete a workout. You've got to connect the bug and initiate a workout before the app will spit any data out at you.
Like Nike+, Fitbit or Jawbone Up, Armour39 is meant to motivate you by quantifying your activities. The difference is, Under Armour isn't pitting you against anyone but yourself. WILLpower isn't meant to impress your friends and the system isn't intended for people who like to brag to their buddies about how fit they are. It's a way for someone who considers themselves an athlete to attach a score to their level of effort at the gym. Obviously, the effectiveness of the WILLpower system will depend on the particular user. For someone like me, who couldn't care less about how many steps he takes, but does want to know if he's really pushing himself as hard as he can on a run, Armour39 works well. However, if you're looking for something that's going to count your calories and monitor your overall level of activity, Under Armour has nothing to offer you.
The problems begin with the price tag: $150 is exceptionally expensive for a heart rate monitor, even one with some advanced hardware features. If the accompanying software were mature and robust, we might be a little more forgiving of the price. Being limited to newer iOS devices is already a significant knock against Armour39, and the fact that the app isn't even properly optimized for the latest generation of Apple handsets (which were already five months old at the time of its announcement) gives us serious pause. Ultimately, Armour39 feels like the genesis of a great product, rather than the culmination of a long R&D process. The company has identified a gap in the market, with a potentially large consumer base, but the combination of price, limited compatibility and a basic feature set undermine its chances of success.