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Thoughts on Heart-rate sensor?

M

MrRage

macrumors member
Original poster
Jun 14, 2008
71
2
I looked at the health app today and it reported that my average bpm is 59, with a range of 32-179. That range seems a little sketchy to me.

So, I grabbed Garmin chest strap and put that on and did a side by side. It was pretty close. The Garmin reports 1-10bps off from the apple watch, but usually the apple watch can get within 1-2bps after a moment of syncing, and almost every time it was lower than the Garmin.

I trust the Garmin because I've seen them compared to an EKG, and both kept reporting the same information.

Now the next test would be to take it out for a run and see how the Apple Watch does.
 
Mine ranges from 41 to 178. I doubt it's ever got that low though. I have a wahoo HRM that I've compared with and the watch is pretty close that I'm happy to trust it since I don't need a super accurate measurement
 
I now have more than 25 workout sessions and more than 10 runs with my :apple:Watch. I have been using sport/HR watches for over a decade and currently use a Garmin 620. I have found the following.

1) The optical HR sensor can be extremely accurate

2) The :apple:Watch MUST be worn a certain way for it to be accurate

Before a work out tighten I the strap up one hole from normal wear and push the band up my wrist slightly. If too loose I get abnormally high HR readings during a run. I use my Garmin 620 on my right and obsessively compare.

IMG_0425%201_zpsppkrztut.jpg
 
From my limited experience of my first workout using my AW yesterday, I'd concur with Julien. My readouts were accurate at times, as compared with readouts from the treadmill, and sketchy at others. I was experimenting with the tightness of the strap and position on my arm throughout my session, and think this played a big part in the variability of readouts.
 
Just did a 11.6 mile run and my Garmin 620 had my average HR at 149 and my :apple:Watch recorded 150. That is very accurate results.
 
Internal AppleWatch heart-rate-sensors verses Bluetooth chest strap

I have an iPhone 6 and an AppleWatch. When a compatible Bluetooth chest strap HRM (i.e., Polar H7 or Wahoo-Tickr) is properly connected to the iPhone, the following will be seen: iPhone Settings>Bluetooth>here you see the name of the Bluetooth chest strap HRM as "Connected".

Open the iPhone App, "Health", and it will list the Bluetooth chest strap HRM when "Sources" is clicked along the bottom of the screen. When the name of the bluetooth chest strap is clicked, "Update Health Data" can be activated.

On the AppleWatch, open the app, "Workout". Now choose an activity and start. By swiping the watch-face to the side,"Heart Rate" can be viewed during the workout. The questions is: Does the watch know to read the Bluetooth chest monitor? Or, use the its own internal watch heart rate sensors? Or, both?

Now open a running App like "Endomondo" on your iPhone (assume it is connected properly to the same Bluetooth chest strap HRM). Take a run and compare the Heart Rate from your AppleWatch (running "Workout") with the Heart Rate you see on your iPhone (running "Endomondo".) If both are using the same information from the Bluetooth chest strap HRM, identical readings should be seen. But, that is not the case!

So, how does the AppleWatch manage this "trade-off" of its own internal HRM sensors when a Bluetooth Chest strap HRM is in the mix?
 
Works fantastically. I check the watch and the metal handles on the workout machine and it's always within 0-3 of the EKG
 
My first Post regarding AppleWatch Heart Monitor needs clarification

Assume a compatible Bluetooth-Chest-Strap HRM (i.e., Wahoo-Tickr) is communicating properly with the iPhone and AppleWatch. Third-party Apps (i.e., "Endomondo",) will "read" the heart rate from the chest strap when that App is viewed on the AppleWatch. It will not use the AppleWatch HR Sensors as part of the display (at least at this point in time.)

However, when Apple's "Workout" App is used on the AppleWatch, it "reads" only the AppleWatch HR Sensors (Not the Chest Strap HRM.) Is this correct?

Is there any way to use Apple's "Workout" App, and restrict the HR display to the chest strap?
 
The how do you view average bpm in the health app?

Edit: never mind, figured it out

----------

Just checked, and the lowest it's ever gotten to is 50bpm. That sounds about right actually. When I'm really relaxed, it gets pretty low.
 
taff2003 said:
From my limited experience of my first workout using my AW yesterday, I'd concur with Julien. My readouts were accurate at times, as compared with readouts from the treadmill, and sketchy at others. I was experimenting with the tightness of the strap and position on my arm throughout my session, and think this played a big part in the variability of readouts.
Click to expand...

I did another gym workout yesterday. I ordinarily wear the sports strap on the fourth to last hole. I tightened the strap to the third to last hole, and secured the watch slightly higher up my wrist than normal. I found this improved the HR results considerably. I did a few spot checks throughout my workout using fingers to take my timed pulse, and the watch was generally spot on all the time.

The only time it seemed to struggle was after I'd done some weights exercises where I assume the movement caused the sensor contact on my forearm to move slightly.

Overall, I was encouraged. My old Fitbit Charge HR never gave me results this close to actual.
 
My range is 41 to 193 but usually around 50bpm at rest. It must work fairly well because I was in the hospital for spinal surgery last year and they had a heart monitor on me the whole time, and it read about the same.
 
Glad to hear all of these success stories. I can never find my own pulse with my fingers about anywhere on myself except for, seriously, inside my mouth. So the fact that a watch can do it at all with what seems to be good accuracy is exciting. I know there are likely ways to monitor all sorts of things based on what I've learned about using light to find out what elements are in an exoplanet's atmosphere. But that's hella expensive, so anything close being in a device starting at $349 is quite impressive.
 
Polar H7 Heart Rate Sensor

Today, I tried pairing my Polar H7 with my watch (had to turn Bluetooth off on my iPhone first). Paired on first try and glances started using data from Polar - first reading and updates were instant. Did a 45mins workout on treadmill using the workout app and it was using the data from H7. Heart rate sensor on the watch was off, it should save battery for long walks/rides.

Once activated, H7 connects automatically to my watch and phone, and once connected the watch turns off its own HR sensor.
 
leventozler said:
....Heart rate sensor on the watch was off, it should save battery for long walks/rides.....
Click to expand...

Running the BT radio continuously (even LE) could use more energy than firing the :apple:Watch's LED/IR sensors. However it is probably about the same but almost certainly no big savings.
 
leventozler said:
source?
Click to expand...

Did you miss could-about-probably and almost?:eek: It is simple physics that operating a radio receiver and transmitter would probably use more electromagnetic energy (BT LE is up to 0.5 watts) than LED's which use about 0.04 watts each (IR a little less and the green a little more).
 
Last edited:
Julien said:
Did you miss could-about-probably and almost?:eek: It is simple physics that operating a radio receiver and transmitter would probably use more electromagnetic energy (BT LE is up to 0.5 watts) than LED's which use about 0.04 watts each (IR a little less and the green a little more).
Click to expand...

It's not that simple. Apple Watch sensors flashes 100 times per second, and BT sends a tiny data packet once or twice per second.

That 0.5 watts figure is wrong. Compared to Class 2, Bluetooth low energy "consumes between 1/2 and 1/100 the power of classic Bluetooth technology." (Class 2 uses 2.5 mW of power (0.0025 watts))

I don't have exact numbers, but power consumption of a BT LE chest strap should be many times less than the heart rate sensor in Apple Watch.
 
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