Fitbit HR Inaccurate

Yeah, I've never been interested in getting a HR monitor device. I started off with the zip and now have settled on the Alta.

indy_cruizer wrote: »

I had the HR and have since switched to the jawbone UP24

Was there much of a difference between the two @indy_cruizer ?

I have the HR Charge. I put my info in on that class-action suit. I'm uncertain if it matters if the number is showing low. but it would be really unfortunate if I think I am working 150 BPM and I am only at 130BPM.

I liked the idea of a heart rate monitor for my workouts and I knew a wrist based monitor wouldn't be as accurate for a workout. I ended up getting a Garmin Vivofit 2 with the hear rate monitor. It started out great and tracked my heart rate so I could get in to the right zones for cardio. Well, it's stopped working now and I don't recommend it. My 15 year old plus polar heart rate monitor works great though, just doesn't have any tracking since it's much older tech, just give you an average at the end.

I pretty much just use my Fitbit as a very expensive pedometer. It is accurate for counting steps. The resting HR is consistent with professional measurements I've had. I don't know or care about HR during other activity.

NorthCascades wrote: »

Yep. My girlfriend returned hers because it was about as accurate as rolling dice when she was exercising. It seemed better when she was sitting down relaxing, but you don't need a heart rate monitor for that.

fitmom4lifemfp wrote: »

It's been pretty well publicized that wrist-based HRM's are not as accurated as the ones with chest straps. Kind of a no-brainer.

While this is true, it's not what we're discussing. Plenty of wrist-based optical sensors work accurately and reliably, Fitbit's just isn't one of them.

It really doesn't matter what wrist-based device you're talking about - none are as accurate as a chest strap that is actually detecting your heart rate straight from the source.

Also, how is FitMom4Lifemfp's response "not what we're discussing"? The topic is about the inaccuracy of the Fitbit HR. Seems pretty on point to me.

MandaB9780 wrote: »

It really doesn't matter what wrist-based device you're talking about - none are as accurate as a chest strap that is actually detecting your heart rate straight from the source.

Mio's wrist-HRMs are accurate. It's very slightly delayed compared to a chest strap, but the exercise community has embraced them because they're accurate and useful. Fitbit's HRM isn't just "slightly delayed," it's off by an average of 20 beats per minute (!!), it's wildly inaccurate. Yes, it really does matter which wrist-device you use, because some are much more accurate than others.

Here is a comparison of a Garmin wrist-HRM against a chest strap. The wrist one isn't flawless, but it does a good job.



Here are two images comparing the Fitbit Charge HR to a chest strap for the same exercise. You can see vague similarities; the Fitbit does not do a good job.

MandaB9780 wrote: »

Also, how is FitMom4Lifemfp's response "not what we're discussing"? The topic is about the inaccuracy of the Fitbit HR. Seems pretty on point to me.

The point isn't that chest straps are better than wrist straps (which isn't really true anyway for most people), and the Fitbit doesn't perform as well as other wrist straps. We're discussing the Fitbit's HR system specifically, not what body part is best.

DorkothyParker wrote: »

Is the offage reading higher or lower during periods of intense exercise?

That's what I want to know

DorkothyParker wrote: »

Is the offage reading higher or lower during periods of intense exercise?

It isn't consistent. It can be wrong in either direction, with an average error of 20 bpm (ignoring times when it could not read at all).

srecupid wrote: »

Need2Exerc1se wrote: »

I pretty much just use my Fitbit as a very expensive pedometer. It is accurate for counting steps. The resting HR is consistent with professional measurements I've had. I don't know or care about HR during other activity.

True but the selling point of the HR is the HR. 20 BPM in either direction is a big difference. Personally I just use a basic vivofit 2 for counting my steps and put on a chest strap monitor for cardio sessions. If a wrist based wearable witb hear rate monitor doesn't have a good heart rate monitor then you might as well save the $50 or so and get the model without it

That's a good point. Luckily mine was a gift.

Actually not so lucky since it was a gift from a close relative who expects me to wear it all the time and quite frankly I don't care what my HR is at every given moment or how many steps I take per day.

My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm

Need2Exerc1se wrote: »

ubermofish wrote: »

My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm

The instructions say to do this during exercise but I have a hard time getting mine to stay up there. It naturally wants to slip down to my wrist because the wrist is smaller. I usually get tired of pushing it back up and just let it go where it wants to go.

You gotta make it pretty tight

MandaB9780 wrote: »

It really doesn't matter what wrist-based device you're talking about - none are as accurate as a chest strap that is actually detecting your heart rate straight from the source.

It's not quite that simple.

Both electrical and optical measurement has some error, and both have a greater level of error at the higher range. At normal range the difference in relative accuracy is pretty negligible, and at the top end that goes from negligible to not very significant.

Factors that affect accuracy include device fit and placement, sampling frequency and with opticals they become vulnerable to skin tone and hair growth as well.

I think the materiality is that for the vast majority of people optical measurement is good enough. That said, the FitBit range do seem to come off worst in most tests I've seen results for.

If, on the other hand, you're interested in rate variation, recovery time, cumulative fatigue and sports performance, then undoubtedly an electrical measurement is superior. For that stuff you're spending 4-5 times the amount of money on a device though.

But when does it cross into personal responsibility? If one has a medical condition that requires them to very closely monitor their pulse (the first thing that's coming into my mind is someone on digoxin who would need to hold their dose if their resting HR is below 60BPM), then it would be rather foolish for them to rely on a more inaccurate piece of technology. If I used a continuous glucose monitor to track my blood sugar (imagine it like how a fitbit measures HR), it would still be my personal responsibility to do a true blood glucose test (pricking my finger and checking it with my meter versus reading what the CGM thinks I am) if I am going to be making a diabetes decision that is highly dependent on my blood sugar (such as determining how much insulin to take to correct for a high blood sugar reading).

I was looking at some stats from my last workout at my university's gym. The elliptical machine I used said my average HR was 144 (3.1 mile distance, about 300kcals burned, 35 min duration, though my hands weren't on the HR bar the entire duration of the workout), while my charge HR says that my average HR was 135 (260kcals burned).

Useful information here. I am thinking about getting a hrm because my resting pulse has gotten super low (high 30s, low 40s consistently) , and my rate during activity has also dropped significantly, just to get more data before seeing a cardiologist.