Fitbits description about it:
24/7 Heart Rate Tracking with PurePulse 2.0
With an all-new multipath sensor, Sense delivers PurePulse 2.0—Fitbit’s 24/7 continuous heart rate tracking for exercise, sleep tracking and everything in between.
Here are some mentions in different reviews since the Sense launched regarding PurePulse 2.0, with key points underlined:
"The Sense boasts improved heart rate tracking with its PurePulse 2.0 technology, which uses a new multi-path heart rate sensor. Basically, that means it’s checking your heart rate in more ways and in more places, which, when combined, should provide a more accurate picture of what your heart is doing. This is something I would have liked to spend more time testing, but early results were promising. I would spike my heart rate doing some exercise and then would manually count my beats per minute using a stopwatch and compare it to the Sense. Not only did the Sense generally stay within a few BPM of my manual count, but it would usually get up to speed faster than the Garmin Fenix 6 Pro Solar, which seemed to have a bit more lag."
- The Verge
https://www.theverge.com/21450123/fitbit-sense-review
"Sense uses Fitbit's new PurePulse 2.0 heart rate monitor, which the company says has an improved algorithm to offer its "most advanced heart rate technology yet." However, I didn't have the best experience with it during my workouts.
To test it out, I wore the Sense, Apple Watch Series 6 , and Polar H10 heart rate monitor, and compared my stats. Throughout three separate runs, I found my average heart rate on the Sense was always off by about 10 to 20 beats per minute (BPM). Now, contrast that with the measurements from my Apple Watch and Polar strap — both of which were only about one to two BPM off from one another.
Throughout my runs, I noticed the Sense struggled to keep up with change in pace in real-time. For example, when I was at a light jog, the BPM on the Sense matched the rest of the devices. But when I'd ramp up my speed and increase my heart-rate, it would take a while for it catch up with both the Apple Watch and the Polar H10.
I also tested it during a quick, 15-minute kickboxing session and ran into the same issue. But this time, the average BPM was off by about 20 BPM."
- Mashable
https://mashable.com/review/fitbit-sense-smartwatch-review/
"We took the Sense for a pretty intense spin session and noticed no unexpected dips in heart rate that indicate an issue with fitness trackers. Our heart rate shown on the watch face mirrored our efforts on the bike, with only a slight delay as you'd expect from any wrist-mounted heart rate monitor."
- Techradar
https://www.techradar.com/reviews/fitbit-sense
"My “biggest” problem with the Sense, however, was heart rate-tracking during exercise. This may be due to the new Pure Pulse 2.0 algorithm, but in general, my workouts had average bpm readings that were about 5 bpm lower than my Apple Watch SE and the Polar H10 chest strap. That’s not that serious of a change. However, I did notice that sometimes the Sense lagged by as much as 10-15 bpm compared to the Watch SE and Polar H10. This wasn’t uncommon in the early days of wearables testing, but I can’t remember the last time I saw two trackers that were more than 5 bpm apart in real time.
This lag didn’t occur all the time, or even in every type of exercise. I only encountered it while running outdoors. Upon reviewing my heart rate data after my runs, however, the graphs from the Fitbit Sense, Apple Watch SE, and Polar H10 corresponded with each other. That leads me to believe Fitbit’s exercise app might struggle to keep up with real-time data for certain exercises. For instance, I didn’t have this problem with strength training, walks, or yoga sessions. This isn’t going to be a problem for everyone, but if you are someone who trains according to heart rate zone, it’s not ideal. I’ve asked Fitbit whether this might be an exercise app issue, but have not yet received a response. Regardless of whether it’s an algorithm or app issue, it’s more of an inconvenience than a sign the Sense is irredeemably inaccurate."
- Gizmodo
https://gizmodo.com/the-fitbit-sense-is-one-hell-of-an-ambitious-smartwatch-1845097433
"First example, this relatively easy paced run , compared to the Garmin HRM-PRO chest strap and Apple Watch SE, both of which were fairly similar, except the Fitbit Sense was often 20+ bpm high..... // .. You can see how for the first 10-12 minutes it’s all over the map – in some cases by 20BPM. It’s nuts.... // ... having a third device to compare against (more soon), I can say without question the Fitbit is wrong here./// .... Or we can go with one of my other faster paced workouts, with a few intervals tossed in. And the Fitbit Sense was wrong almost the entire time, by at a minimum 10bpm (which, is a lot). And sometimes 15-20bpm. It’s the yellow line at the bottom. /// ...In fact, the only thing that performed worse than it was the Whoop 3.0 strap, because…well, Whoop. In fact, during a few runs, I started wondering if Fitbit had licensed the tech from Whoop, since it was often equally as bad and often failed in semi-similar ways. The yellow line of the Fitbit Sense, and the blue line below are similar during these intervals. Low, slow, and inaccurate. // .... Look, it’s bad. And even when it somewhat appears close above – that’s only because you’re skewing your expectations by the parts it’s 10-20bpm off. Being 3-5BPM off looks ‘normal’ by comparison, but that’s still wrong. And bad."
- DCRainmaker
https://www.dcrainmaker.com/2020/09/fitbit-sense-in-depth-review-all-the-data-without-the-clarity.ht...
Conclusion:
It seems to me like the PurePulse 2.0 really won't be much better than the old one, and won't be enough for those/us who do intense gym workouts and HIIT. While it is a mixed result, some of these reviews point out the same issue that is found in the Versa 2, which is that it rarely keeps up with the BPM during intense workouts. This means that I will continue to have to bring my Polar H10 to the gym.
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My History:
I bought the Versa 2 on release day and was extremely hyped about it. Quickly I realized it's flaws however ,especially considering the HR monitor. It just wouldn't measure my HR correctly during workouts.
Several indepedent tests had the same result as me;
The HR monitor on the Versa2 worked fine while doing nothing, but as soon as I hit the gym it totally missed everything. Weird part is; it got it mostly correct whenever I was running. No matter if I was outisde running or on the mill, it was pretty accurate with a variation of 2-3 BPM from my H10. But as soon as I did a gym workout session, it completely missed.
Compared to the Polar H10, which is highly accurate, the results during one month of gym workout 6 days a week was:
- missed average HR of 15-20 BPM
- missed peak HR of 15--20 BPM
- missed burned calories with 200-300
Where the Versa 2 showed lower numbers than the H10.
I've discussed thjs issue in the forums and had several other avid gym-goers with other types of accurate HR monitors try it out, and they all had the same results. Obviously I scoured the forums and talked to customer service about this issue and did everything they recommended as well as everything they didn't; having the watch sitting lower down not so tight, having it higher up real tight, switching arms, all kinds of different distances and tightness levels etc. I even tried shaving where the watch sits to ensure maximum readibility.
