HR works very good when still

[SunsetRunner]

As I do weight-training the HR is all over the map. When I stay still it gets corrected within 3 seconds. Once I stand up it's all over the map again. Showing a lot less than what I am.

[jharla1]

My first weight training workout with the Sense was this morning.  The HR was very very disappointing.  It was routinely below by as much as 20 bpm.  By the end of the workout, compared against my Versa 2 I was a good 75 calories burned less, with noticeable differences between fat zone and calorie burn.  Several times I used the treadmill heart monitor as well as timed it on my own pulse and it wasn't anywhere near (again, around 20 bpm light).

Pretty disappointed.  Perhaps it's a software fix so not going to just send it back yet.  But am currently charging the Versa 2 to continue using in the meantime.

Still ran into problems with the button pressing when lifting, even with just the button on the left.  Haven't done a deep dive though to see if you can lock the watch during workout (you couldn't on the Versa 2, which is why I wanted to upgrade... constantly hit the right button on my gloves pausing the workouts mid set).

[Dman1138]

Just got my sense and resting HR seems about the same as my Versa. HR is definately 10-20 bpm lower then my Versa would measure during exercise.

[Rich_Laue]

Is the watch right on the wrist? The flexin of the wrist is the problem, try moving it up the arm, right above the wrist joint. This is what Fitbit reccomends. 

[Dman1138]

I'm wearing the Sense in the same location I've had my Versa for 2 years, so I don't think thats the issue.

[mikecyprus]

How do you know its the Versa more accurate and not the Sense? 

[Laly04]

I’ve tested the Sense on elyptical last night, along with Polar chest strap and watch: it took Sense about 2.5 min to catch up the HR, then it kept it almost at same rate as the chest strap as long as the workout was constant. When doing intense short intervals, it was delayed in catching up by 10-15 bpm for at least 30 seconds.

Did weights training today, by the time I would have finished a set of 10 rep, Sense would catch up the bpm but still showing less than in reality; I haven’t tested it with the Polar though, forgot it at home.

Sort of disappointing for the first Fitbit device 😕 owned.

[SFN]

I'm having the same issue.  Resting HR is accurate, but when I checked my HR manually several times during exercise, the Sense seems to be running 20-30 bpm low.  My Versa was very accurate at rest and during activity.  Flipping the Sense to the underside of my wrist improved the accuracy, but I prefer not to have to do that, since you then have to tap the screen to see stats because the auto screen wake trigger gets confused by wearing that way.  And half the time, tapping the screen tried to pause/end my workout or started cycling through the stats due to delayed response and "overtapping".  Hope Fitbit will fix this HR issue with an update!