Heart Rate Monitor Problems with Blaze and Surge

[RichardLA]

I've owned my Blaze for about six months now. During that time it has been replaced once after FitBit approved the replacement. This RMA was due to the heart rate monitor failing. Unfortunately, the replacement is doing the same thing as the original. As I mentioned in my support case, when I start a walk, the HR monitor works fine until my heart rate increases (usually above 120 bpm) and also when the altitude changes. The altitude doesn't even need to change that much. It seems to happen when there's maybe less that 100 feet of difference in elevation? I think the most contributing factor may be due to the buildup of persperation on my wrist underneath where the sensors sit. These trackers are supposed to be "moisture resistance", correct? I know I'm not the only one who owns a FitBit and also sweats.

I went through all the recommended suggestions: no lotions/sunscreens on the area where the sensors are at, clean wrist, clean sensor area, remove/re-add tracker to FitBit app, unpair/re-pair bluetooth with phone, reset the tracker, etc. Nothing corrected the problem with the original and the replacement. I could, however jiggle the tracker on my skin and it seems to, I guess, make a better contact once in awhile. At that point the heart rate will come back, but often times it drops off again. It will resume a steady monitoring once I get back to a level walking path or walk downhill.

I began to think that, maybe it was the shape of my wrist. I began wearing my tracker underneath my wrist, since my veins are right there. That seemed to help but the HR monitor still "flatlines" under the previously-mentioned conditions. Interestingly enough, I happened to see an online ad in a private forum that I'm on. The user was selling a Surge, along with the REPLACEMENT that FitBit sent him. Guess what? He also mentioned the same HR monitor problem that I am describing here, as to why he was selling it. So now I've come to the conclusion that there is either a software glitch or firmware glitch in the tracker, or both. I further suspect that FitBit knows about this problem but is refusing to acknowledge it because it may require redesigning all the code that makes the FitBit do all the things that it does. I am stating that I SUSPECT that this may be the case. I don't work for FitBit, nor am I one of their software developers. I just find it odd that I happened upon someone else who was selling his pair of trackers due to the same problems that I'm reporting here. I also want to add that I think FitBit has a great product here. It does some amazing things, but the HR monitor reliability is a very serious flaw in my opinion. FitBit is refuting these and quite frankly, it doesn't surprise me that they are.

Moderator edit: word choice

[shipo]

@RichardLA, I strongly suspect you are not wearing your Blaze snugged down enough.  I've experienced inconsistencies with the heart rate monitor on my two Surges when worn too loose, and as soon as I snug them down a notch, the issue is solved.  And yes, I sweat, a lot, so much so my Surge has a layer of condensation under the screen.  In fact, so much so I actually had a car, which had passed me while I was running up a long 8% grade, turn around and tease me he had to turn on his windshield wipers after he passed me.  🙂

By the way, the blood flowing through your veins and arteries are not what the HRM is sensing, the sensor picks up the capillary action just below the skin.  Said another way, wearing the tracker under the wrist or in the normal outward facing position will make no difference in accuracy (as you've discovered).

[bbarrera]

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@RichardLA wrote:

I've owned my Blaze for about six months now. During that time it has been replaced once after FitBit approved the replacement. This RMA was due to the heart rate monitor failing. Unfortunately, the replacement is doing the same thing as the original.

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@RichardLA Read this article:

http://www.wareable.com/sport/optical-heart-rate-tech-the-experts-speak-9763

In particular this quote: 

"It's physiology not technology. It's a matter of the unpredictability of the blood through the wrist in an area you can't control. Ear tech is going to beat the wrist because it suffers less physiological interference."

sums up the reality of optical HRM on the wrist. Its also why optical arm bands are better than wrist trackers, but only one company has embraced the arm (Scosche Rhythm+).

I thought this quote in the comment section was priceless:

"You would not buy a watch that inaccurately measures time so why buy a heart rate monitor that inaccuracy tracks heart rate. You can afford to miss a few seconds, surely accuracy around HR is quite the opposite. Go buy a sundial"

Just a little comic relief to a serious topic. Anyways, a lot of good info in that article from two optical HRM pioneers (and a chest strap company for balance). 

What Fitbit doesn't like to tell you is that physiology varies from person to person, and that impacts wrist-based optical HRM accuracy. What works for @shipo may not work well for you and me, its an indisputable fact that wrist-based optical HRM works well for some and not others, and for some activities and not others. Even more interesting is that optical HRM accuracy varies from device to device, for me (cycling) the Surge is least accurate, and Blaze is nearly as good as Apple Watch. All three are completely inaccurate when I'm working out with barbells and dumbbells. Some of that is likely related to fit, as some tracker designs are better at a) keeping outside light away from the sensor, and b) minimizing motion.

I own a Surge, Blaze and Apple Watch. IMHO Apple does a much better job of describing the factors affecting optical HRM technology:

"Many factors can affect the performance of the Apple Watch heart rate sensor. Skin perfusion is one. A fancy way of describing how much blood flows through your skin, skin perfusion varies significantly from person to person and can also be impacted by the environment. If you’re exercising in the cold, for example, the skin perfusion in your wrist may be too low for the heart rate sensor to get a reading.

Motion is another factor that can affect the heart rate sensor. Rhythmic movements, such as running or cycling, give better results compared to irregular movements, like tennis or boxing.

Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance. The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings."

My biggest issue with Fitbit is they won't allow importing HR (and GPS) data, and they won't allow pairing a tracker with bluetooth chest strap.

[RichardLA]

@shipo, Thank you for your response.  I assure you that the tracker is secure on my wrist.  If it was not, then I would think that the HR monitor would flatline regardless of what my heart rate, altitude, and amount of persperation is.  As I mentioned, it only seems to flatline when I reach a higher BPM, in combination with the other two factors.  There is no difference in how secure the tracker is on my wrist from one condition to the next.

Regarding wearing my tracker under my wrist, why would the HR monitor reliability be better than wearing it on top of my wrist?  There's definitely a difference in how the HR monitor on the tracker functions.  At least in my experience.  In either position, the HR monitor continues to flatline under the described conditioins.

[RichardLA]

@bbarrera, thank you for your comments.  🙂