Fitness trackers have come a long way since they simply counted your steps. Now many of them are bona fide smartwatches, helping bring your phone to your wrist while also providing a boatload of metrics you can use to track both your fitness and your health.
That emphasis on data and metrics is one main reason I was eager to try Fitbit’s newest flagship smartwatch, the Fitbit Sense. Replacing the Fitbit Ionic—its predecessor and my daily fitness tracker—the new Fitbit Sense promises a whole host of data at your fingertips, including tracking of your breathing rate, heart rate variability, skin temperature, and oxygen saturation levels, along with tried-and-true workout data you’d expect from a fitness tracker.
Since I found the Fitbit Ionic reliable, comfortable, and accurate enough to serve as my fitness tracker for nearly two years, I was excited to see what Ftibit’s newest iteration of it had to offer. So I put it to the test—and was pretty darn pleased in the process.
How I Tested
Our panel of fitness experts helped us determine the criteria to focus on when testing fitness trackers and fitness smartwatches, including measures like accuracy, ease of use, battery life, comfort, style, and other features.
I tested the Fitbit Sense for one week, taking it off only when it needed to be charged. During that time, I wore it on my left wrist and kept another fitness tracker I’m testing on the right to serve as comparison. Over that seven-day period, I used the Fitbit Sense to track outdoor walks and runs, (virtual) indoor cycling classes, and at-home strength training sessions. I also wore it to sleep each night and while showering.
Ease of Use
Although I’m super familiar with Fitbit, I was initially thrown by the new design of the Sense: Unlike the Ionic, there are no actual buttons on the watch—it’s touchscreen only, with one larger haptic button on the left side. The haptic button (which you cover with your thumb to engage) took some getting used to, but once I figured it out, the rest of the setup was smooth sailing. The button, though, ended up bugging me a little during regular use.
Everything with the Fitbit Sense is done on one app on your phone, a welcome change from some of the other fitness trackers I’ve tested, where you need to download one app for the watch’s configurations and another to actually look at your data.
One thing I really appreciated with the Fitbit Sense is that it’s customizable, so the more you use it the easier it becomes to use. For instance, the Sense has a huge listing of exercise shortcuts on its workout screen—including things I’m not really into, like golf, swimming, and martial arts. Swiping through that list to find the workout I needed was a bit of a drag, but I soon realized the watch remembers your recent workouts. So my most-used types stayed right at the top of the list, making them very easy to find. The Sense also allows you to set shortcuts and move icons around, so you don’t have to go scrolling through multiple screens to find apps you use more often. For instance, I use the alarm and timer apps frequently, so I moved them onto the first screen.
One thing that wasn’t quite so intuitive, though, was its outdoor workouts settings. The first time I used it for a run, it defaulted to no GPS (which made my pace and distance way less accurate). I didn’t realize I needed to turn it on in the running settings, but after I did, it stayed that way and didn’t cause any other issues.
Accuracy
The main reason I stuck with my Fitbit Ionic for so long was that it was solid on the distance-accuracy front: When I’d run with friends, their watches would generally have our distance as several hundredths of a mile greater than mine—not a huge deal, but it made our pace look slightly quicker. But once we ran a measured road race with our respective watches, it turned out the Ionic was pretty much right on target.
And the Fitbit Sense follows suit: There’s a measured distance within my neighborhood run that I know is exactly 0.5 miles, and the Fitbit Sense registered that either right on the nose or within one or two hundredths of a mile. When my runs were over, there was no surprise with my pace (some other fitness trackers tend to overestimate distance by a tad, which results in some esteem-boosting vanity pacing, but that’s not an issue with the Sense.)
When I manually measure steps on the Fitbit Sense, it stays accurate with that too. The 50 steps I counted walking back and forth in my apartment measured 51 on the Sense.
As for heart rate accuracy, I noticed the Sense tracked some kinds of workouts more closely than others. The Sense measured my heart rate during my walk-runs like a champ—showing steady peaks in the 160s during run intervals, falling down to the 120s during walking recovery (making it right in line with the fitness tracker I wore on my other wrist). But during my indoor cycling workouts, which include tons of high-intensity intervals, the Sense seemed to lag about five to six beats per minute under the other devices I used. (I also used a heart rate forearm band during these workouts, since it pairs with my Peloton app.) In a couple of indoor cycling workouts too, the Sense’s heart rate plummeted to the 120s when I was at peak work—more than 30 beats per minute below what it should be—for about 30 seconds before it caught back up.
Battery Life
Smartwatch trackers are hard on battery life, so I wasn’t expecting much here. Still, I got two solid days of heavy use—which included one GPS-based workout and three non-GPS ones—on a full charge. As the 48-hour mark approached, the watch remained at 35%, so it actually could have lasted another night, but I knew I was going to use it for a workout first thing in the morning and wanted it charged up for that.
Comfort
Thanks to a design change with the Sense, the band is even more comfortable: The default band tightens and tucks in on the inside of your wrist, meaning there’s no way for the excess tail end to come loose or catch on things. It’s also a soft silicone, which makes it breathable and nonabrasive during sweaty workouts.
The Sense also has a streamlined profile, making it way less likely than bulkier watches to catch on clothing.
Style
With its sleek design, I’d feel just fine wearing the Sense on nearly any occasion. I tested the dark gray version, which I found to be understated and subtle, but the Sense also comes in a really pretty white-and-gold version, if you’re looking for a little more pop.
Syncing
Workouts appeared almost immediately after pulling up the app on my phone, so syncing was a breeze. There was a slight delay in nighttime metrics like sleep tracking when I woke up—I’d need to refresh a few times before seeing the data—but it only took a few minutes to show up.
Water Resistance
The Fitbit Sense is water resistant, meaning you can shower with it. However, Fitbit doesn’t recommend you do so, since it raises the risk of exposure to shampoos, soaps, or conditioners, which can mess with your device. Full disclosure: I learned this after showering with my device for a week (and my Ionic for about two years), and I didn’t notice any issues. I also wore the Sense during a run that started misty at first and later developed into some full-fledged rain, and it held up just fine in that too.
Other Features
One area I think Fitbit really shines is in its nighttime tracking, and the Fitbit Sense is no exception. Like many trackers, it gives you a sleep score, which it determines based on a whole host of sleep-time metrics. But it also breaks up your sleep into cycles, giving you the time you spend in light sleep, deep sleep, and REM sleep—and the time you spend awake (the latter being super sensitive, meaning it picks up on awakenings you might not even remember in the morning). It also gives you an estimate on your sleep “restoration,” which it calculates based on the percentage of time your heart rate while sleeping is below your resting heart rate and the percentage of tossing and turning you do. I’ve found the sleep resting heart rate particularly helpful to monitor, since I’ve noticed I tend to spend more time in sleep above my resting heart rate the more stressed I am or the more I go overboard on my workouts without allowing for adequate recovery.
Along with sleep data, the Sense also tracks a bunch of other health metrics, including heart rate variability (the time between heartbeats, where a higher number may be linked to better health measures), breathing rate, skin temperature (displayed as a deviation from your baseline, which it gathers the first three nights you wear the watch), and oxygen saturation. It’s interesting to see your “normal” for these metrics—and to see if you deviate from that in any way—but it’s important to know that this tracking is not intended to be used for medical purposes, as Fitbit’s medical disclaimer states. These metrics were a big reason why I was eager to test the watch, but for a health worrier like me, I realized they could be toeing the line into information overload if I wasn’t careful with how I used them. (I will admit to a slight morning freakout when I noticed a pretty solid dip in my heart rate variability from the night before.)
The good news for people like me is this is pretty easy to prevent: These data points are tucked into a separate Health Metrics page on the app, meaning if you don’t want all that info at your fingertips all the time, it won’t be staring you right in the face—you’d have to seek it out.
On the smartwatch front, the Sense acts as a helpful extension to your phone for when you’re not able to get to it (say, when I’m clipped in during a cycling class). The Sense allows you to respond to texts with preset options (which you can tweak to customize in the app) or through a talk-to-text option. What was especially helpful? The “retry” button: The microphone tends to struggle with clarity (especially, as I noticed, when you’re out of breath), so you may need to try a couple of times before it gets it right.
The Bottom Line
The Fitbit Sense does everything you’d want a fitness tracker to do and comes in clutch on the smartwatch side too. Its additional tracking metrics are just a happy bonus—and that’s probably the best way to think of them for right now.
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