Your smartwatch is lying to you
Summary
TLDRThe video script discusses the discrepancies in resting heart rate readings among various wearable devices. It highlights the issue of manufacturers using different algorithms, potentially misleading users about their fitness levels. The script compares the resting heart rates measured by Fitbit, Mi Band, and Apple Watch, and explores the possibility that sleeping heart rate could be a more accurate indicator of health. It calls for standardization and transparency in how these devices measure and report resting heart rate.
Takeaways
- 📊 Different wearable devices use various algorithms to measure resting heart rate, leading to inconsistent results.
- 📉 Example: Fitbit measured 53 bpm, Mi Band 51 bpm, and Apple Watch 44 bpm for the same person, illustrating the disparity.
- 🩺 Resting heart rate is typically defined as the heart rate after about 5 minutes of inactivity while awake.
- 🔍 The lack of transparency in manufacturers' algorithms makes it difficult to understand how they calculate resting heart rate.
- 🌙 Some manufacturers, like Garmin, WHOOP, and Oura, calculate resting heart rate based on nighttime measurements.
- 😕 Nighttime heart rate measurements can be misleading, often showing lower values due to physiological changes during sleep.
- 📉 Using lowest nighttime heart rate as resting heart rate can give a false sense of fitness.
- 🤔 There's a correlation between sleeping heart rate and resting heart rate, but they're not perfectly aligned.
- 📚 Current studies indicate sleeping heart rate might be a better health indicator than daytime resting heart rate.
- 📈 Until standardized measurement methods are established, comparing heart rate values across different devices and medical recommendations remains challenging.
Q & A
What problem does the speaker highlight about wearable manufacturers?
-The speaker highlights that many wearable manufacturers are providing misleading information about users' resting heart rates.
How do different wearables vary in measuring resting heart rate according to the speaker?
-Different wearables use different algorithms to measure resting heart rate, leading to discrepancies in the reported values.
What are the resting heart rates reported by the speaker's Fitbit, Mi Band, and Apple Watch?
-The Fitbit reported a resting heart rate of 53 bpm, the Mi Band reported 51 bpm, and the Apple Watch reported 44 bpm.
Why is there a discrepancy in the resting heart rates reported by different devices?
-The discrepancy arises because different devices use different algorithms and methods, such as taking a waking measurement or a 24-hour average.
What does Dr. Rohin Francis say about the measurement of resting heart rate?
-Dr. Rohin Francis explains that different devices measure heart rate using various algorithms, and earlier devices like the Fitbit used to take a 24-hour average, which could be misleading.
How is resting heart rate typically defined?
-Resting heart rate is typically defined as the heart rate measured after at least five minutes of inactivity while the person is awake.
Why might manufacturers prefer to measure resting heart rate during sleep?
-Measuring resting heart rate during sleep might provide more consistent and accurate readings because the person is lying still and ambient light levels are low.
What is misleading about the Oura Ring's 'lowest RHR' value?
-The 'lowest RHR' value provided by the Oura Ring is misleading because it is the lowest resting heart rate value captured during the night, which may not accurately reflect the true resting heart rate.
Why do some manufacturers choose to report resting heart rate values measured at night?
-Manufacturers may choose to report night-time resting heart rate values because these readings are more consistent and might flatter the user by appearing lower, encouraging positive feedback and continued use of the device.
How can users get a true reflection of their overall health regarding resting heart rate?
-Users can get a true reflection of their overall health by measuring their heart rate after sitting still for five minutes, rather than relying on the resting heart rate values provided by wearables.
What does the speaker conclude about the comparison between sleeping and resting heart rate?
-The speaker concludes that while sleeping heart rate might still be a good measure of health, it is currently hard to compare with traditional resting heart rate measurements due to a lack of standardization and comprehensive studies.
Outlines
🤔 Discrepancies in Wearable Resting Heart Rate Measurements
This paragraph discusses the inconsistency in resting heart rate readings from various wearable devices. The narrator highlights their personal experience with three different devices—Fitbit, Mi Band, and Apple Watch—yielding different results, raising the question of accuracy. It is explained that these devices use different algorithms, and some, like Fitbit, may take a 24-hour average, which can be misleading. The paragraph also introduces Dr. Rohin Francis, a heart specialist, who clarifies that resting heart rate should be measured while awake and inactive for at least five minutes. The lack of transparency in the algorithms used by manufacturers is criticized, and an attempt is made to understand how different devices calculate resting heart rate by comparing them to all-day heart rate measurements from a Polar H10 chest strap, which is considered a more accurate measure.
🏋️♂️ The Impact of Device Algorithms on Resting Heart Rate Perception
The second paragraph delves into how different wearable manufacturers calculate and report resting heart rates, with a focus on those that use sleeping heart rate as a proxy, which can be misleading. The Oura Ring is specifically called out for providing a 'lowest RHR' value based on sleep data, which may not accurately reflect the user's true resting heart rate. The paragraph also touches on the potential reasons why manufacturers might opt for nighttime readings, such as increased accuracy due to stillness and lower ambient light, and the possibility of enhancing user satisfaction by providing flatteringly low heart rate numbers. The narrator shares their own experience with a cardiologist regarding their low overnight heart rate and emphasizes the difficulty of comparing these readings to the standard medical range of 60 to 100 bpm. The paragraph concludes by suggesting that users should manually measure their resting heart rate for a more accurate assessment of their health and fitness.
Mindmap
Keywords
💡Wearables
💡Resting Heart Rate
💡Algorithms
💡Fitbit
💡Apple Watch
💡Mi Band
💡Heart Rate Measurement
💡Dr. Rohin Francis
💡Sleeping Heart Rate
💡Polar H10 Chest Strap
Highlights
Wearable manufacturers may be providing misleading resting heart rate data to users.
Different wearable devices use different algorithms to determine resting heart rate.
Resting heart rate is typically defined as the heart rate at rest, usually after at least 5 minutes of inactivity while awake.
Some devices may be using a 24-hour average to determine resting heart rate, which can be misleading.
Algorithms behind wearable devices are not public, making it difficult to understand how they calculate resting heart rate.
Comparisons of wearable devices' resting heart rate measurements to all-day heart rate measurements can provide insights into their methodologies.
Some manufacturers, like Garmin, WHOOP, and Oura, calculate resting heart rate based on readings taken while the user is asleep.
The Oura Ring's 'lowest RHR' feature may mislead users into thinking they have a lower resting heart rate than they actually do.
Low resting heart rates recorded during sleep can be misleading, as physiological changes during sleep phases can cause heart rate to slow significantly.
Manufacturers might report resting heart rate at night to make users feel healthier or to encourage subscription retention.
Overnight heart rate measurements can be more accurate and consistent than daytime readings due to the user being still and ambient light levels being low.
The lack of standardization in resting heart rate measurement makes it difficult to compare data between different wearable devices.
Resting heart rate values from wearables may not align with the standard medical range of 60 to 100 bpm, leading to potential misunderstandings about health.
Sleeping heart rate might be a good measure of overall health and fitness, but more research is needed to establish its validity.
One study suggests that sleeping heart rate could be a more accurate predictor of risk of death and heart disease than daytime resting heart rate.
The advent of wearable technology allows for continuous heart rate monitoring, which could lead to new insights through future studies.
Until a standard for heart rate measurement is established, device manufacturers may be confusing or misleading customers with their readings.
Transcripts
As you can see, I like my wearables (this one’s just a wedding ring by the way), but I was shocked
to find out that many wearable manufacturers are outright lying to users. And most frustratingly,
it’s about one of the most important numbers that these devices give you: resting heart rate.
The best way to illustrate the problem is to look at my resting heart rate as
measured three watches I wore for a week when I was testing their performance.
Fitbit: 53 beats per minute. Nice. Mi Band: 51 bpm. That’ll do.
Apple Watch: 44 bpm. Hang on…what?!
So who’s right? Am I reasonably fit, with a resting heart rate in the low 50s,
or a full-on athlete, at 44 bpm? I mean, it’s the former, obviously. But what’s going on here?
The problem is that different devices use different algorithms to determine
your resting heart rate. Over to Dr Rohin Francis,
heart specialist, and who you might know from his excellent YouTube channel, Medlife Crisis.
There are different algorithms for a lot of how the different devices measure heart rate,
and I think nowadays most of them will take a waking measurement. But certainly an early
Fitbit that I had seemed to just take a 24-hour average, which gave me a very misleading figure,
way lower than what I was measuring my resting heart rate to be in the daytime.
The key thing here is how resting heart rate is usually defined:
as we found out in the last video…
This is your heart rate at rest. So that typically means when you're not doing
anything for at least a few minutes, so about 5 minutes of inactivity while
you're awake. \[comedy echo\] …while you’re awake…while you’re awake…while you’re awake…
And what’s frustrating is that the algorithms behind these devices aren’t public so,
while they’re no longer quite as stupid as just taking a 24-hour
average, we still don’t know exactly what the manufacturers are doing here.
We can try to work out how different manufacturers pick the resting heart rate by comparing them to
my all-day heart rate measurements. These are all the readings of my heart rate on a day when
I was testing out a few different devices, ranging from just below 40 bpm at the low end to 160-odd
bpm at the fastest while I was exercising. These values from a Polar H10 chest strap, so they’re
the closest we can get to my true heart rate, to compare with an Apple Watch, Fitbit and Mi Band.
We can split these up into the times when I was active, resting or asleep,
and then overlay the watches’ estimates of resting heart rate, like this. The Fitbit and the Mi
Band both seem to choose a value close to the bottom of the heart rates when I wasn’t moving,
which makes sense. But it’s hard to know what Apple is doing here: it looks like maybe they’re
basing it on values while I’m asleep, but their website is pretty vague about how it works.
Some manufacturers are a bit more explicit about what’s going on – but three big ones
I found information for, Garmin, WHOOP and Oura, all specifically and proudly explain
that they calculate your resting heart rate while you’re asleep!
The Oura Ring is particularly misleading, giving you one value called ‘lowest RHR’,
which they define as ‘Your lowest resting heart rate value captured during the night’.
My resting heart rate on the night I was deepest sleep was 34, which again very,
very low. If I look at that, if that's what my Oura Ring had told
me my resting heart rate was, I would think, man, I am super fit.
Yeah, you’re Tour de France level.
Exactly. And yet, clearly that is not the case. You know, just just just look at me.
Oh, harsh.
That just bears no resemblance.
Noooo, that’s very misleading. And you'll see often people slow,
profoundly in sleep. So I have tried this on myself and I was hitting sort of 30,
I was hitting 28 …when I was a bit fitter than I am now!… but very transiently, you know,
there are physiological changes depending on which phase of sleep you're in, and in some of them
you can go really slow. So that would be really misleading to say that’s your resting heart rate.
Some of you in the comments on the second video in this series were concerned about
my low overnight heart rate, and suggested I should see a doctor.
So, first, thank you for your concern – but then I did check with a cardiologist, and his response
was … to show off that his used to be even lower. Which means, I guess I’m probably OK?
But why do so many manufacturers report resting heart rate at night when that’s not
the conventional definition? Well, let’s start with the possible cynical reason:
if your Oura Ring flatters you by telling you that your resting heart rate is super-low, you
can brag about it to your friends at the gym and post screenshots from the app on your Instagram,
and you might be more likely to be happy with your Oura Ring and maybe keep paying the subscription?
There is a potentially less cynical reason too: as we saw in that earlier video,
heart rate measurements taken overnight, when you’re lying nice and still and ambient light
levels are low, are often more accurate than the daytime ones, sometimes substantially so,
so readings will probably be more consistent than measurements taken during the day.
Unfortunately this does mean it’s very hard to compare between manufacturers. If a Fitbit,
Apple Watch and Oura Ring user all walk into a bar, the guy with the Oura Ring
may emerge the smuggest about his resting heart rate – the Apple user is obviously
the smuggest overall – but it might be that the Fitbit-wearer is actually fitter
than both of them, despite his watch giving him a higher value for resting heart rate.
The bigger problem is that all of this makes it very hard to compare
with the standard medical range, usually given as 60 to 100 beats per minute,
where most of us should probably be aiming for somewhere toward the lower end of that range.
These numbers were established in big medical studies where resting heart rate was measured
by a doctor or a nurse in a clinic, not by taking a 24-hour measurement and then trying
to extract the lowest possible number to make the user feel good about themselves. If you
were looking at this graph of heart rate vs risk of death from the last video and thinking ‘wow,
my Garmin says I’ve got a resting heart rate of 43 bpm, I’m gonna live forever!’, Well, I’m afraid
I’ve got some bad news. Which is a shame, because that’s exactly what my new Garmin is telling me.
These values could make us think that we’re healthier than we actually are. An Oura Ring
user thinking their resting heart rate was 60 bpm might think that they’re pretty healthy. But,
if they’re basing that on their lowest sleeping heart rate, then that’s very misleading – if
it’s anything like mine, 20 bpm below their actual resting heart rate. So, if you do have
an Apple Watch, Oura Ring, Garmin or WHOOP strap, don’t rely on the resting heart rate measurement
values in the app – if you want to compare yourself to the classic 60–100 bpm range,
or your gym buddies who use different devices, then just you’re going to have to sit still for
five minutes and see where your heart rate ends up to get a truer reflection of your overall health.
In spite of all this, sleeping heart rate might still be a good measure. It would definitely
make sense that people with a lower resting heart rate during the day had a lower one at night too,
but sadly the only paper I could find that made the comparison directly was done in teenage
athletes, so quite a specific population, and there were only 11 of them in the study, which
means it’s not exactly definitive. Do let me know in the comments if you know of any better ones!
So I decided to take a look at my own data. On this graph every point is a day, and along the
bottom is my resting heart rate that day, and up the side is my sleeping heart rate that night. As
you can see, there’s a pretty clear relationship. The points lie fairly close to a straight a line –
for the nerds, R squared is 0.7, where 0 would be no correlation and 1 a perfect correlation – and,
on average, my sleeping heart rate is about 9 beats per minute lower than my resting heart rate.
So it does seem plausible, given that resting heart rate is a good measure of overall health
and fitness, sleeping heart rate could be too. %%r = 0.849, r^2 = 0.72%%
Another study I found correlated sleeping heart rate and resting heart rate across 600 people,
and found an R squared of 0.25 – meaning that, between people (rather than just within me),
they are related, but not quite as strongly. But actually, the fact that sleeping and
resting heart rate aren’t perfectly correlated might be because sleeping heart rate is better:
the study found that sleeping heart rate was a more accurate predictor of risk of death and risk
of heart disease than the daytime resting heart rate was. This is just one study, compared to the
huge weight of evidence for we’ve got for resting heart rate – but it does seem possible, maybe even
plausible, that sleeping heart rate could be a pretty decent measure – and that would be a happy
coincidence for device manufacturers, who find it easier to measure your heart rate at that time.
Historically, it’s been very hard to measure heart rate overnight in a large population,
because you’d have needed to strap them up with expensive medical equipment – it was far cheaper
and easier to take a one-off measurement sometime during the day. But of course,
wearable technology now means that we can monitor heart rates in huge numbers of people 24/7,
so hopefully new studies will shed some more light on this – and I wouldn’t be shocked if
sleeping heart rate did turn out to be better than conventional waking resting heart rate.
The trouble is, until we have those studies and we come up with some kind of standard, it’s really
hard to compare values between manufacturers, devices and the normal medical recommendations.
And all that means, for now, many of the leading device manufacturers are at best confusing,
and at worst misleading their customers.
So, share this video with any friends who use one of these fitness-tracking wearables – especially
if yours is a Fitbit and theirs is an Oura Ring. Or Apple Watch. Or Garmin.
Watch more videos from my series on smartwatches here or, speaking
of algorithms, the YouTube algorithm thinks you’ll enjoy this video next!
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