
Show HN: Continous Heart Rate for Android Wear and Apple Watch - brandonb
http://www.cardiogr.am
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saspect
Capturing HR once a minute is of really limited use. More than benchmarking
against resting HR, the interesting thing is to look at heart rate
variability, and to do that you need to scan several times per second. For
that using purpose-built devices is just better. I am thinking:
[https://jawbone.com/store/buy/up3](https://jawbone.com/store/buy/up3) or
[http://www.getqardio.com/qardiocore-wearable-ecg-ekg-
monitor...](http://www.getqardio.com/qardiocore-wearable-ecg-ekg-monitor-
iphone/)

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photonic29
Photoplethsymographic heart rate requires a lot of algorithmic compensation
for noise and motion artifact. There are some pretty sophisticated strategies
available for beat interpolation, but individual R-R intervals are
tremendously more difficult to recover accurately against real-world noise.
HRV measurements are also very intolerant to error in R-R interval, and even
less so to dropped beats. There are certainly conceivable solutions to these
problems, but no major manufacturer of PPG based consumer heart rate devices
allows access at a level low enough to get R-R time series or understand R-R
interval confidence. OEM module manufacturers for pulse ox devices do allow
direct serial access to the PPG waveform for those interested in hacking at
it.

~~~
brandonb
This is really useful! Would you mind emailing me at brandon@cardiogr.am? I'd
love to know more.

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photonic29
Hey Brandon, I replied to you from an address containing 'dash'.

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brandonb
Hey! I'm the OP. Let me know if you have any questions.

Just for fun, this was my heart rate while launching this:
[https://twitter.com/AppCardiogram/status/591377862441046016](https://twitter.com/AppCardiogram/status/591377862441046016)

~~~
DenisM
Is there any watch on the market that has enough battery to do real continuous
HR monitoring? Last I checked, they all only measure continuously in the
"sport" mode for an hour or two, and in the "regular" mode they measure HR
once every 10 minutes or so.

~~~
kevlened
I have a Fitbit Charge HR that checks every second during exercise and every 5
seconds otherwise. The battery lasts about 4 days for me.

[https://www.fitbit.com/chargehr](https://www.fitbit.com/chargehr)

~~~
DenisM
Indeed, found this on the linked page:

 _Stores heart rate data at 1 second intervals during exercise tracking and at
5 second intervals all other times_

Thank you!

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arexi
An app like this could save a life one day, for sure. My uncle recently died
from a heart attack. It's impossible to know for sure but perhaps if he'd been
wearing a smart watch, it could have told him to seek help before it hit.

~~~
davegardner
I'm not a doctor, but based on what little research I've done in the past, a
basic heart rate monitor such is this is unlikely to provide any pre-warning
of a serious cardiac event.

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potomushto
I use a fitness tracker called MIO Fuse - it's a great сontinious Heart Rate
Monitor, but Mio has very painful and useless both Android and iOS app. I wish
to have access to raw data or integrate it with something like Cardiogram
because it's really insightful to see how your heart responds to various
events.

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ianstallings
I'm curious about the privacy aspects of it. Can anyone elaborate on where and
how the data is stored?

~~~
_asummers
In a related question, does anyone know of any monitoring product (e.g. FitBit
or whatever) that does NOT send your data to a centralized server outside of
your control?

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calvin_c
As far as I know the Apple Watch is the only one that doesn't sync to a server
somewhere. All data is kept stored in HealthKit on your device.

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martingordon
How does this work on Apple Watch? AFAIK, WatchKit doesn't give access to the
heart rate sensor.

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ddmf
Thank you so much, I had hoped that there would be something like this inbuilt
with motofit/google fit but was quite disappointed when I discovered how
inadequate and manual it was. I don't need to sell my android watch anymore.

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blazingswrd
Hey Brandon, I'm doing usability research at Virginia Tech on EEG's and EKG's.
I'm trying to figure out how to do continuous heart rate for Apple Watch for
an app/study.

How are you getting the Heart Rate on the watch? I've looked into WatchKit and
I couldn't find anything about getting the heart rate back out of the device.
I was thinking about using Healthkit to try to do something similar. If
there's any chance, we could talk/skype sometime, please let me know!

~~~
brandonb
Sure, email me at brandon@cardiogr.am.

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bbarn
OP - I love the concept, but the execution isn't there. I installed it on my
Gear Live, and it pops up a "Heart Rate" notification, that until acknowledged
leaves the heart rate sensor on. (the green light underneath). This would
obliterate the battery. It needs to do it's thing, and go away, not wait for
me to tell it to, or even notify me at all. I'm not sure with the API if this
is possible or not, but for now, I'm sorry.. it's just not usable.

~~~
brandonb
Thanks for trying it. The notification actually doesn't control the sensor
(green light) -- I think the timing was likely just a coincidence.

That said, we haven't had a lot of people with Gear Lives test the app yet, so
it's always possible you've stumbled on some novel bug that only appears on
certain hardware. Wouldn't be the first time. :)

If that behavior is reproducible, can you send a bug report to
brandon@cardiogr.am?

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stephengillie
Cool! How soon until you can tap into a calorie app/database (MyFitness?) and
start to guesstimate the user's caloric burn rate each minute?

~~~
brandonb
That's a frequent feature request, so hopefully soon--the thing I'm not sure
of is whether those things are even close enough to accurate to be worth it. I
think "guesstimate" is a great word for it. :)

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dannyr
Does Google Fit handle heart-rate data?

It'd be great if I can access my data there.

Nice work! I've been looking for something like this.

~~~
brandonb
We do indeed sync the data to Google Fit—so it both reads your activities
(walking, running, biking) from Google Fit and any connected apps you have,
and writes the raw heart rate measurements back to Google Fit.

~~~
dannyr
Cool.

I just realized who you are.

Taking time off from healthcare.gov?

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brandonb
Oh! I wrapped up my involvement last fall. It was a 2-month rotation that
became 3 months, then 5 months, then 8 months, ...

After taking a couple months off, I started collaborating with some UCSF
researchers--we know that in the next few years, millions of people are going
to be wearing heart rate monitors. But what does that mean for healthcare? Can
we actually detect things like heart attacks or lethal arrhythmias before it's
too late? Could we potentially build the "check engine light" for your heart?

So that's what this app is a first step toward.

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mintplant
Great! I've been looking for something like this.

Uh, now I just need an Android Wear device...

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brandonb
I have a Moto 360 and like it a lot!

It was recently on sale for $180, and I'm going to guess it'll be on sale
again, since the Apple Watch is just starting to ship and new Android watches
are expected to be announced around Google IO in late May.
[https://moto360.motorola.com/](https://moto360.motorola.com/)

Note: the heart rate monitors on these early devices aren't great! We have to
do a lot of work to make sure the sensor works well and the graphs are
understandable. But I think the hardware will improve rapidly in the next 6-18
months.

~~~
mintplant
Thanks! I guess I'll hold out for a while on the device, then. Good luck with
Cardiogram!

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j_m_b
I've read the Apple Watch will have this feature built in.

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IBM
You can read about it here.

[https://support.apple.com/en-us/HT204666](https://support.apple.com/en-
us/HT204666)

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cllunsford
Nice work! Quick tip on the copy: continuous has two u's.

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brandonb
Well, that's embarrassing. I'm sure both my math and English teachers are
shaking their heads right now. Fixed!

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sekasi
I'd love to hear some thoughts on how this affects battery, especially on some
battery-challenged devices such as the moto360 ?

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brandonb
Way better than I expected—on my Moto 360, total battery consumption is
usually 1-2%, and the beta testers have reported the same. In my experience,
the biggest optimization you can do for Moto 360 battery life is to disable
tilt-to-wake, since the most power-hungry part of the watch is the display.

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sdrothrock
I've been using Cinch up til now; it would be great if Cardiogram sent the
data to Google Fit to graph like Cinch does!

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brandonb
It does send the data back to GFit! Warning though—the GFit graph isn't
necessarily built for this resolution of data. That's part of why we built our
own chart to show you the details.

~~~
sdrothrock
That's great to hear! I barely touch Google Fit myself; I was more wondering
about it because I use Google Fit to send HR data to gyrosco.pe.

