Heart Rate Inaccurate During High-Intensity

[SunsetRunner]

OK, I'll admit I was initially contributing to the Charge HR thread on this topic but as I now have a Blaze, thought I'd continue here.

Did some high intensity work this morning, 6x500m, to see how the Blaze's HR monitoring would cope. I ran a compairson with my Polar chest strap, and yes I know they will differ 🙂 , that's why I've got the chest strap.

BPM at end 1st interval

Polar 162

Blaze 141

2nd

Polar 167

Blaze 159

3rd

Polar 170

Blaze 163

4th

Polar 174

Blaze 139 (kinda lost it there - think I was starting to sweat!)

5th

Polar 178

Blaze 162

6th

Polar 180

Blaze 166

So, all in all, a bit off but I think, given the Blaze's bigger size, I need to find a better position for it during these sort of work outs. I wasn't really comfortable with it. But to be fair, it did pretty well for itself first time out, even if lagging behind and sort of lost it a bit in the middle. Inever really expected it to cope with this sort of activity.

[AdamMSC]

Thanks for posting this!

[SunsetRunner]

@SunsetRunner thanks for the info, I put your data into a table to calculate the % difference between the two trackers:

Interval   Polar   Blaze   % Difference

1             162     141      -12.96%
2             167     159      -4.79%

3             170     163      -4.12%
4             174     139      -20.11%

5             178     162      -8.99%

6             180     166      -7.78%

Short of interval 1 & 4 (which you mentioned the reason for the discrepancy) seems like not too far off compared to what I consider a more accurate method of HR detection (chest strap).

[mitwess]

your results are actually better than i would have thought. the fact is almost all optical hr sensors are not good at tracking interval training. this is something fitbit should just be more upfront about to consumers, that their hr tracker is good at slow trends but less accurate at rapid hr changes. dcrainmaker.com has had a lot of good material on this, most sensors just cant track quick large hr changes very well.

[SunsetRunner]

---

@mitwess wrote:

your results are actually better than i would have thought.

---

Well this morning the Blaze really impressed me. OK, not high intensity intervals but rather a steady 30mins row, with HR at 135 - 145. Throughout the whole row the Blaze was either spot on the same as my Polar or only one or two beats out. More often, the same. The finishing HR was 143 from the Blaze, 142 from the Polar. The total clories burnt was 313 according to the Blaze and 316 from my Concept 2 / RowPro combo.

I'm very happy with my purchase. I'll put up my next split intervals when next done, as I think I've sorted positioning of the Blaze.

[adammiarka]

---

@mitwess wrote:

your results are actually better than i would have thought. the fact is almost all optical hr sensors are not good at tracking interval training. this is something fitbit should just be more upfront about to consumers, that their hr tracker is good at slow trends but less accurate at rapid hr changes. dcrainmaker.com has had a lot of good material on this, most sensors just cant track quick large hr changes very well.

---

You mean like this FAQ about what affects heart rate accuracy? 

https://help.fitbit.com/articles/en_US/Help_article/Heart-rate-FAQs#ImpactsAccuracy 

[SunsetRunner]

Mine was really off yesterday during a run. It was randomly showing my HR at 90 (I was closer to 150 during my intervals), and this morning during a 3mph walk, it insisted my HR stayed at around 155 (which is completely off).

[bbarrera]

---

@adammiarka wrote:

You mean like this FAQ about what affects heart rate accuracy? 

https://help.fitbit.com/articles/en_US/Help_article/Heart-rate-FAQs#ImpactsAccuracy 

---

Not there, being more upfront means not overselling it on this page:

https://www.fitbit.com/purepulse

[SunsetRunner]

Tested again on the treadmill for 15 minutes. 3mph walk. Blaze claimed my HR stayed between 150 - 160. I was most definitely nowhere near that range. Played around with how high it was on my wrist, but didn't have any luck getting it to be more accurate.

[vinotauro]

Not sure why there's a ton of inaccuracies. I wore mine during my shoulder workout. It stayed accurate every heavy sets (I also palpated heart rate to compare)

[Koshka]

I must admit I am finding it less accurate than my Charge HR for lower intensity exercise. The Charge HR was inaccurate for high intensity exercise and during stuff like weight lifting. I wore a HR monitor, the Blaze and my ChargeHR (Charge HR was on a separate account) while walking on a treadmill at about 2.6 MPH with an incline. The HR monitor and Charge HR were very close to each other. The Blaze was saying my HR was in the 120s and 130s. But that was no where close to where I was which was really around 100 to 105. I've noticed this several other times. I am doing something fairly low in intensity and the Blaze says my HR is way higher than it is. Yes, I am following instructions on how to wear it.

[SunsetRunner]

Another day another row and this comparison just to show how fickle the Blaze is. Not even close, pretty much ever. Thought I had it in the right position, tightness etc too. Pah! Back to the drawing board 🙂

For Info, the spike down in the RowPro/Polar graph is when I stepped off the rower to answer the door 😄

[SunsetRunner]

Oh dear, Blaze fails again today. Did 2x10 mins and Blaze was miles off.

To be fair to the Blaze though, I did try it in a different position, on the inside of my wrist. It never really got close, so don't think I'll try that again.

Oh, @SteveCordingley said I'd let you know.

[dvdmon]

I'm going to see if I can get my old Polar (with chest band) working and compare, but unless I'm having some serious health problems, I think the Blaze is completely unreliable except when sitting or standing around.  If I start walking, I go from 110 or 115 to 150 within a few minutes, and that's walking pretty slowly - probably about 2.5mph.  It will go up and down a lot, maybe getting has high as 160 and back down to 125 seemingly rendomly.  It also will just stop giving me a number for a while.  At the gym yesterday doing 3.5mph on a flat surface it was staying in the 180's for a few minutes at a time, going as high as 189.

I really hope that Fitbit releases an update that fixes the issue.  The Charge HR was not great, but at least, given a little time, it would catch up to what you currently were doing.  With the Blaze, it just seems like it's all over the place!