I love smart clothing. If made right, smart clothing could be the key to unlocking the future of health and fitness technology. Smart clothing, or clothes with sensors that measure different aspects of your health and fitness, is still rare, with only a handful of products on the market. The Hexoskin Smart Shirt ($399 for a complete starter kit with one garment) has made some great inroads into this space. Available for both men and women, it's a workout top with almost invisible sensors for measuring heart rate and breathing, plus a small tracker device that connects to the shirt to capture your motion, like cadence, steps, acceleration, and so forth.

The Hexoskin Smart Shirt has some flaws and costs a pretty penny, but with so few comparable products on the market, it's hard to say whether the price is too high. A comparable line, the Athos Smart Workout Pants and Shirts cost $298 for a starter kit, although they measure muscle use, sets and reps, heart rate, and (in the shirt only) breathing. So Athos is really made to be worn only during workouts. The Hexoskin shirt, on the other hand, has other sensors that let it double as an all-day tracking device. You can even wear it to quantify your sleep.

The Tracker and Compatibility

The Hexoskin tracker device is a small, Bluetooth-enabled device that's smaller than a credit card and fits into a secure pocket on the side of the shirt. Inside the pocket is a little connector that fits into the device and lets it collect data from the sensors. The device then sends the information it gathers to your phone, where it's collected in a companion app for iOS or Android.

The device has three LEDs on it, and after using the thing for several weeks, I still have no clue what they mean. I know there's a blue light that needs to flash when pairing with Bluetooth, but other than that, I simply have no idea what the lights mean. The app doesn't have an explanation (I wish it did), and it's certainly not intuitive enough to figure out on your own. On the bright side, the device worked, so maybe it doesn't matter if I know what the lights mean. C'est la vie.

A USB charging cable comes with a Hexoskin device, too, and the battery lasts about 14 hours. The device can store about 150 hours worth of data, so if you forget to upload your workouts for a day or two, it's no big deal.

Wearing and Washing Hexoskin

I don't know if you'd want to wear the same shirt all day long and then to bed, but the point is you could. Or you can buy additional shirts for $169 each. The shirts, which are made of polyamide microfibers, feel similar to bathing-suit material. They're machine washable on the gentle or "hand" cycle, although you do have to disconnect and remove the Hexoskin device before submerging it.

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As I mentioned in a recent article on smart clothing, fit matters tremendously. Clothes need to fit you for comfort, but with smart clothing, the sensors in them have to make good, consistent contact with your skin, too.

The Hexoskin Smart Shirt feels comfortable, but the women's tank rides up. There are sensors both at the chest, in the elastic band of a built-in sports bra, and the waist. The women's tank comes with a belt designed to hold the lower part of the shirt in place, but on me, it still rode up. I removed the belt and was more comfortable without it, and my data still came through just fine.

According to the sizing guide, my measurements pegged me at just barely fitting a medium, and I wish I had gone for the small. There's way too much room in the boobs. Keep in mind that the sensors need to touch your skin, so you can't wear a second sports bra underneath if the tank is loose. Size down, ladies!

The Hexoskin App

The Hexoskin app shows you whatever data point you want to see being plotted on a graph in real time: heart rate, speed, cadence, and so forth. The other measurements appear at the bottom next to their icons so you can check in on other stats at a glance. You don't have to leave the screen on, however, and can put your phone out of sight if you prefer.

The app comes with a lot. A huge list of activities are supported, from badminton to snowboarding. You can use it not only to track your workout times, speed, breathing, and heart rate, but also to conduct a heart rate deceleration test, which is an indicator of health. Faster deceleration from maximum heart rate is better, and the app is pretty clear about showing what your results mean. You can also use it to test your heart rate variability, which is an indication of whether your body has recovered enough from a previous workout to get at it again full-force today.

Unfortunately, Hexoskin's app isn't the most suave looking thing I've ever seen by a long shot, and it could stand to be a heck of a lot more responsive, too. Perhaps the most frustrating aspect of the mobile app is setting it up. I learned through a lot of trial and error that if you don't make a complex enough password, the app rejects you from creating an account, but it doesn't tell you that a weak password is the cause. Instead it says the service is unavailable. Rookie mistake.

Another problem with the Hexoskin app is that it doesn't sync your information automatically to the Web account. To get all your details online, you have to connect the Hexoskin device to your computer via a USB cable, download a piece of software, run it, and log in. In fact, you have to do this step to see complete details in the mobile app, too, as some of your history and Timeline information will be blank until you do. The information should transfer and sync wirelessly, because that would make the whole system simpler, seamless, and more elegant.

Smart Shirt, Middling App

Though expensive, the Hexoskin Smart Shirt is a great product that tracks a wealth of information about your workouts and activities. The mobile app has some wonderful functionality, too, but it could use some love and attention from the design side. The same can be said for the tracker device and its incomprehensible LEDs. Unlike the Athos apparel that should be coming to market any day now, the Hexoskin shirts don't measure muscle output. So if you're looking for detailed advice on, say, whether you're favoring one side while you lift weight or cycle, lean toward Athos instead. But if you're more interested in heart rate and breathing, and want to run some fun heart health tests on yourself, Hexoskin will probably keep you busy for a while.

If smart clothing sounds like overkill for your fitness needs, check out the best activity trackers instead, as well as my advice on how to choose a fitness tracker that's right for you.