HRV and SPO2 accuracy on Sense?

[hawaiichica]

Just got Sense. The resting heart rate measurement seems accurate at rest, however I have concerns about the accuracy of the HRV and SPO2. For SPO2, I have a separate Pulse Oximeter. When compared, the Sense reading is always a bit lower. So far, the HRV result I've gotten is very low. Considering the averages for my age and my overall health, this seems very off, and I will be testing HRV on another device. Has anyone else noticed these issues?

Moderator edit: updated subject for clarity and label.

[Shellyb66]

My hrv is 25ms as well. Am overall healthy resting heart rate 64, 0xygen 96 , so not sure if this is right considering we are all getting the same hrv

[Elsa2]

I too have this going on, I’m a healthy active person but this HRV score of 24 makes me wonder about some dark underlying issue and yet there’s no information provided to make sense of it from the app. Definitely a short coming - I just got my watch and I’m regretting it now that I see the accuracy of some other products for HRV.  Frustrating 

[Micsb]

HRV 24 is allright, research show that this will be impacted by age, gender and race. For me hrv rmmsd should average at 31ms being white, male and 45 years old. My Sense so far has measured it between 23 and 35ms. It is a great indicator of when you are restituted vs exhausted. Best at comparing your own daily hrv measurement, less useavle for comparing with others.

0 is very bad.

[t.parker]

I am curious what Fitbit understands as HRV as HRV usually is given as quantified number and is a result of data analysis. It is more like a score which can be easily interpreted. Raw RMSSD without any context and analysis would be useless for a regular user. So what does Fitbit show as a result? If it's raw RMSSD then @Micsb may be in fact right. Most people would have rather low RMSSD (depends on the age group though). I compared my average RMSSD against my age group:

Interesting thing is that for the majority of the population in my age group is RMSSD = 33ms (approx). So the question stands - what is the result value given by Fitbit and how should it be interpreted by users?

[SunsetRunner]

Yeah HRV is garbage on Fitbit I slept in a very in comfortable polar H10 chest strap last night to compare and verify what I was seeing from Fitbit! The polar showed 62ms HRV Fitbit versa 2 showed 15ms fitbit should delete this HRB option entirely as the 15ms reports I have been getting from Fitbit sent me into a spiraling panic as it means my life is soon to be at its end! I am a former pro athlete in late 40’s all my annual checkups have me as very healthy “elite athlete “ demographic versus Fitbit putting me in the 85 year old out of shape Democrats it relates to HRV

[SunsetRunner]

Demographics * and I slept uncomfortably I hate Apple auto spell 

[t.parker]

@SunsetRunner FYI you can edit your posts. You will see the option after tapping 3-dots next to your reply 🙂

[SleepBandit]

Soooo glad you wrote this.  I don't think the HRV is accurate at all on the fitbit.  I played college sports, run 8-minute miles, lift weights regularly, was told by my doc when then did my stress test cause I am just over 50 that I process oxygen at an "athlete level".   My BP, resting heart rate 56/57, cholesterol, etc. are excellent.  Yet my HRV says I am 85 years old.  It was 25ms last evening.  I don't trust this feature at all.    

I think we all need to take this fitbit for what it is - a novelty.  This is not a health device.  

[SunsetRunner]

Exactly I just finished doing splits for 60 minutes on my rowing machine chest strap had me peaking at 225bpm (I am in your age group) dropping to 60bpm in under three minutes at rest and the Fitbit last night showed me at 11ms too funny thanks for the confirmation of the same situation because I guess you never know!

Enjoy the holidays

[SunsetRunner]

I also have no readings for these in last 3 days.  Shows sleep.  That’s it. Ive reset the watch as well.  Feel  liked I got duped on this purchase. 

[SleepBandit]

Thanks!   Same to you!    

[SleepBandit]

I think the issue is if you're in very good shape the device has a hard time figuring out what's going on.   When I got my heart study they kept me overnight.   I wore a halter monitor.  The nurse comes in from the hall and I am with the night nurse giving blood.   The hall nurse is like "is everything ok in here?"   Yes, why?   "his heart rate is 47."  LMAO!    So I am just not sure the fitbit is able to deal with these types of variables.  

[SunsetRunner]

Fitbit is good for basic monitoring there aren't any activity watches that do more than a “fair” job of calculating HRV and SPO2. I was also concerned when these features first appeared (as they erroneously reported numbers equating to a person twice my age) then after diving into the research I realize like in life there is no shortcuts if you want HRV or SPO2 accurately then you need the tracking devices designed specifically for that purpose. I believe it was an error due to market competition that these features even show up on a smart watch.

It is a great tool to track diet water intake and daily exercise with a clock face. If whoop had a clock face I would prefer that device for fitness tracking but for a watch Fitbit is really the best of the smartwatch devices available although they all perform in a lesser function as related to devices specifically designed to track a single key performance indicator.

[Hazza85]

I’ve been getting lately 90% to 93% spo2 levels during my sleep but on a oximeter when I wake up it says 99% 

how accurate is this spo2 sensor (versa lite )

my HRV is average between 50ms & 78ms

with a RHR of 56 to 59 

[Micsb]

It might be accurate if the oximeter measured spo2 after you woke up, whereas the Sense measure it during sleep. For reference, I usually have 95-97% during night, and a week ago it decided to measure spo2 during a short nap to 99%. According to several articles on the internet, spo2 is normally lower during sleep. My own non sciencetific tests with the Sense, show a correlation between ventilation in the bedroom during night and the Sense reported spo2. It seems sensitive enough to register impact on spo2 due to ventilation changes, in my case off or on.

I doubt HRV measured by Sense is compareable with measurements done with chest straps, other devices or under other conditions. Some research uses average HRV over a whole day. I am convinced the resisistance in the blood fluid and elasticity of the veins will impact the HRV when measuring blood flow on the wrist compared to measuring the electrical impulses from the hearth. I only use it to gauge the variations and I assume Fitbit, having collected this data from a large popultion, use it to estimate the responsive score under stress levels. 

Even from before I had Fitbit when I frequently used my polar, incl chest strap to monitor HRV, I only used the results to look at my own variations. The test protocol, was a 5 min measurement period resting, at the exact same time each day. There would be large variations between morning, midday and evening. I am very carefull comparing my HRV with anything else but my own, or at least others of the same demographic measure under the exact same conditions. Here Fitbit has the advantage of measurement results from a very large population, measured by the same devices under the same conditions.

[Micsb]

Here is an example of how mich HRV will variate during the day, even changes in sleep schedule can make significant impacts on the result. Please bote that below is not measured by fitbit devices and might not directly compareable with our results.

HRV being largest between 2200 and 0200

 

[SunsetRunner]

All valid points thanks for that detailed explanation. I have confirmed with my trainer and MD who both suggest a HRV baseline is most critical at the same time saying they would not trust any baseline not taken from a chest strap or laboratory stress test. Further, they would only feel comfortable with results of a full blown medical examination which is the only indication they would use to determine overall heart health. (Of course that is what they would say)

[Micsb]

Hi Wolfric, I agree on both statements. To properly evaluate the reported value a baseline is required, as we are comparing with our own HRV and not other persons. Polar recommended in their usermanual to take one week of complete rest in order to find the restitution level. From hereon I could see the impact from training. 

I find the Sense measured HRV being a good indicator for restitution and when I should consider to take a restday. It seems to be consistent in how it measures HRV, it correlate with changes in RHR as sciencetific research show and is pretty spot on to show a drop when I have had a glass of wine too much the day before.

The convenience of having this measured automatically everyday is awesome. It just seems limited only going back 1 month and not being able to register a personal baseline.

I assume this has something to do with the national health authorities and general fear of lawsuits, that they have to be very carefull about having measures reporting good or bad health and then take the blame if it proves wrong. Dont want everyone running to the doctor when HRV drops due to drinking too much and only getting a few hours of sleep. Just see on this forum how quick everyone are at blaming fitbit for doing unnescessary visits to the doctor.

[SparkyDad]

100% agree!

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Have you tried the Whoop yet. Heard it’s much better

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Same here. Day 1: 22. Day 2:18. And to make matters worse my resting heat rate is rising to FitBit has me ready to go to the ER in the mind.  I feel fine otherwise. 

[SunsetRunner]

Whoop is better for sure but I want a watch as well not just a band. If and when they ever come out with a proper watch I will definitely switch to whoop. I do have a whoop tried it for a year and went back to Fitbit for the lack of a functioning watch. I am not a slave to my cell phone so the need to have the cell phone near me all the time was a big reason for me not keeping the whoop strap. Although technology wise I believe whoop was superior to Fitbit.