Review: Fitbit Charge HR

I find myself in a quandary about activity trackers. I'm already a very active person—a competitive athlete, even (I race bikes). Do I need one? How can a little rubber band help me improve my health?

A simple step tracker isn't worth the wrist real estate. But the latest trend in wearables has piqued my interest: heart-rate tracking. Specifically, continuous, all-day heart-rate tracking that's just as accurate when you're sitting at your desk as when you're jogging in the park. It's a challenge for wearables for two big reasons: non-stop heart-rate monitoring takes a toll on device battery life; and it's a lot more difficult to capture accurate heart rate readings from your wrist, which is often moving, than from a monitor strapped snugly across your chest.

The new Fitbit Charge HR is one of many new wearables that can read your heart rate. As your heart beats, your capillaries expand and contract due to changes in blood volume, and Fitbit's band uses two bright green LEDs (proven in scientific studies to be more effective at monitoring heart rate than other wavelengths) to shoot light into your flesh and detect these blood volume changes beneath the skin. The lights flash continuously—by monitoring your heart rate non-stop, you can glean information like your true resting heart rate or how intense your workouts are. You can also learn when you're getting stressed out and get a better estimate of how many calories you burn each day, which are particularly useful for maintaining or achieving weight and blood-pressure goals. Color me intrigued; I strapped one on.

The Charge HR comes with some detailed guidelines on how to ensure you're tracking your heart rate correctly. You're supposed to wear the band one finger width above your wrist bone, and double or triple that distance during exercise. Also, after last year's recall of the Force wristband due to skin irritation issues, the company has explicit guidelines for keeping the device clean and dry if it gets sweaty.

I was impressed with the depth of the instructions (and also that it didn't give me a rash), but I wasn't as impressed with its heart-rate tracking as I'd hoped. Fitbit's mobile app automatically breaks down heart rate into three zones: peak, cardio, and fat burn, based on the often used (and often inaccurate, and in my case extremely inaccurate) method of calculating max heart rate based on 220 minus your age. By this math, if you're 30, your max heart rate is 190.

When walking, running, cycling at a casual pace, or at rest, the Charge HR's heart-rate tracking seemed accurate, measuring the gamut from my resting heart rate in the low 50s to "fat burn" levels in the 130s. Above that, it got wonky. It could sometimes measure "peaks" into the 160s, but according to a heart rate strap, I spent a good amount of time in the 180s. I set a custom zone up to my actual max heart rate in the app, but it was unable to detect a heart rate that rapid. I should hedge here—my results may be an edge case, since my hummingbird heart baffles even my cycling coach. This is a problem average Fitbit users should be aware of, albiet one they may not encounter regularly.

In almost every other aspect, the Charge HR excelled. Like all Fitbits, it tracks steps, distance, calories burned, and floors climbed, which, being more experienced in this space than almost any competitor, it does with aplomb. The form is similar to that of the Charge, which came out in late 2014, but with a watch band-style clasp. The band is made of an exceedingly soft, supple rubber that feels velvety to the touch: smooth on back, textured with a diamond grid pattern on top. I really like the material, except that because it's stiffer than a traditional watch band, it can be finicky to notch its buckle tongue into the band's adjustment holes, and secure the end of the band into the free loop.

Fitbit's sleep-tracking algorithms, while not incredibly detailed, are accurate. I wore the band to bed every night, and it could ascertain what time (down to the minute) I hit the sack, as well as what time I woke up. Unlike other sleep trackers, there's no need to press a button to indicate bedtime or the morning wake-up call. In the app, it relays when you were asleep, restless, and awake in a color-coded sleep pattern graph. It's not quite as detailed as the Microsoft Band's sleep analytics, which can differentiate between light, deep, and REM sleep. But it's still useful in getting a handle of your overall sleep quality. The Charge HR takes into account motion and heartrate in its sleep analytics, unlike previous FitBits that only tracked movement.

The mobile app remains a well-designed, easy to navigate tool for looking at your data, monitoring your fitness progress, and also tracking your food intake and water consumption. I was also able to easily port that information over from MyFitnessPal, where I already do most of my tracking.

I had only one other major complaint about the Charge HR: It's not waterproof. For a device designed for all day, everyday, and athletic wear, I want to be able to strap this thing on and leave it on until it needs to be charged. It is water resistant—that is, sweat, rain, and splash-proof—but on multiple occasions I forgot to put it back on after showering, losing over half a day's stats. And once, I accidentally left it on in the shower (it was fine).

So back to my original quandary. This wearable is not for hardcore athletic monitoring. For that, go for something like a Garmin Forerunner 920XT or a Polar V800 and a heart-rate strap. That said, the Charge HR is a good tool for monitoring daily activity and moderate workouts, and for getting better insight into what your body is doing while you're focused on, well, living life.

Fitbit also sells a cheaper Charge that does everything except track your heart rate. It costs $130, and the Charge HR costs $150. That extra $20 for heart-rate monitoring over the Charge? It's a no brainer if you're just tracking a few 5-mile runs or regular gym sessions per week. And the charts and data gathered in the Fitbit app can be enlightening, and even entertaining—you can pinpoint when you ran to catch the bus, or climbed three flights of stairs to the office (although there's no guarantee that this novelty factor won't eventually wear off).

While this Fitbit may not be the Cinderella slipper of my wearable dreams, I would absolutely recommend it to family and friends.