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Show HN: Continous Heart Rate for Android Wear and Apple Watch

cardiogr.am

62 pointsbrandonb53 comments

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 or http://www.getqardio.com/qardiocore-wearable-ecg-ekg-monitor...

I thought the Up3 only measured resting HR.

You are right. A few months ago Jawbone UP3 definitely had HRV listed in the heart health features. That's specifically why I was looking to buy it. I guess that's close to impossible with an optical sensor.

Even the standalone optical HRMs (e.g., Scosche RHYTHM+) aren't good enough to do HRV[1] even though their accuracy compares favorably with the chest strap models[2]

[1] http://www.dcrainmaker.com/2014/05/scosche-antbluetooth-opti... about 10% down the page [2] http://www.dcrainmaker.com/2014/05/scosche-antbluetooth-opti...

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.

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

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

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

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.

We've had surprisingly good experiences—generally the beta testers are reporting 1-3% battery consumption, and I think we could sample more frequently.

I think if we can get true, beat-to-beat monitoring, the health implications would be huge. Doctors don't care a whole lot about steps, but they definitely care about heart rhythm.

Sorry if this is a dumb question, but 1-3% over what time period? Per hour? Per day? Or are you saying it increases the normal idle power consumption by 1-3%?

1-3% per day, as measured by the "watch battery" panel in the Android Wear app. (Mine is currently at 1%).

How often do you sample?

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

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!

I have the Samsung Gear 2 Neo, and tried building an app to record HR all day sampling once per second. A full battery lasts about 12 hours in this condition. However, the heart rate monitor subsystem crashes fairly often, and gets very inaccurate with pretty much any arm motion. So not super useful.

Basis, Amiigo (not yet for sale), and even Epson have wrist-based trackers which claim some form of continuous heart rate monitoring. The Epson in particular seems interesting, as they developed the sensor in-house with a focus on power management; they say it can record continuously for 40 hours.

I have the Gear Fit and while it doesn't crash, the sport mode is very inconsistent while running. Tightening the band might help but it's uncomfortably tight.

Suunto's watches have done that for a while now (5-6 years?), though they use a capacitive chest strap, rather than the optical method used by smart watches.

Edit: And as far as I know, Suunto was really the first company to pursue measurement of HR variability. They have some interesting whitepapers, if you use the Google.

Does this report heart rate data back to Google Fit, or does it only read info from Google Fit?

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.

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.

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.

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

We have servers that store the raw data and run the algorithms on it, and then it's also synced to Google Fit (on Android) and HealthKit (iOS).

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?

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.

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

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.

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!

Sure, email me at brandon@cardiogr.am.

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.

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?

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?

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. :)

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.

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.

Cool.

I just realized who you are.

Taking time off from healthcare.gov?

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.

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

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

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/

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.

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

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

You can read about it here.

https://support.apple.com/en-us/HT204666

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

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

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

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.

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!

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.

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.

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