Saturday, September 30, 2023

Optimize for reducing friction, and data quality, but don't forget about identity.

 In the past couple of years, I have invested in both a FitBit Inspire 3, and a Polar Verity Sense heart rate monitor.   The purpose was to closely track heart rate during workouts so that I could stay in a prescribed zone during training.

What I found with these devices was that the data was OK, but keeping them charged, carrying them with me, wearing them, and wrangling the Android apps that go along with them was kind of a faff.   Over the last month I have found a real joy in leaving them at home, and just using the hand heart rate sensors on the treadmills that I use. 

Over the next couple of days I'm going to try to validate both the FitBit and the hand-sensors with the Polar monitor in order to make sure that the values I'm getting are accurate.  However, beyond that, I no longer see a need to continue to incorporate these devices into my routine.

This in essence is optimizing for 'friction' in the sense that by using the hand sensors I am taking a few steps out of my workout prep.  I can just throw on a pair of shorts, and hop on the treadmill.  I am no longer inhibited by whether the devices are charged, or functioning optimally.

One other factor though is the psychological, or effects on identity, of wearing a Fitbit constantly.  Wearing a Fitbit identifies me, as a heavy person, as someone who associates with people actively working towards health. Mine has a loud orange band, and I feel communicates my interest in fitness through style.  As a fashion accessory it communicates visually one of my main interests, and is therefor still valuable in that role.  

Inspire 3 underreports heart rate versus an ECG strap during running.
(The Quantified Scientist - YouTube Video)

I'm starting to suspect that the Fitbit's heart rate data isn't all that accurate.  This may be a flaw with mine, the way I'm wearing it, or even body hair at my wrist.  This raises a problem though, because I don't actively want to be surfacing misinformation about heart rate when I look at the accompanying app, or scroll through the display on the device.  The fashion/identity role is not worth polluting the metrics with bad data.  No data is better than bad data. dashboard modified to remove bad heart rate data.

I haven't quite reconciled these two roles, fashion/identity, and heart rate tracking, other than to potentially invest in yet another device that is both beautiful and also accurate.  Again though, if I were purely optimizing for reducing friction, I wouldn't wear a device at all.


I validated that 2 different Lifefitness treadmills and the Polar Verity Sense agree with each other and agree with my perceived exertion.   The Fitbit was consistently low, sometimes up to 20bpm low.  

Furthermore I realized I don't like the motion of checking the wrist while on a treadmill.  I would feel differently if I did more MAF work outdoors where checking the phone is slightly inconvenient although not terrible. 

Conclusion: optimize for friction, continue to use the hand sensors on the treadmills from the previous pattern.  They don't require any faff with charging, or having equipment with me.  Use the Polar Verity to validate when I think there is an issue or I want more continual tracking. 

Keep the Fitbit as a fashion accessory as long as I don't get sucked into checking it's erroneous  heart rate data. Use it as a step counter.   Unfortunately you can't turn off heart rate tracking altogether, and it looks like a piece of tape over the sensor would get in the way of charging.