Fitbit and Resting Heart Rate

Fitbit SurgeI’ve been so impressed by the Fitbit HR range of activity trackers that I’ve just posted my trusty Forerunner 920XT on eBay. I am no longer going to pretend that I may one day compete in another triathlon or go swimming more than say, once a year.

Instead I’ve opted for the Fitbit Surge and will be content with exercise auto recognition, continuous daily heart rate monitoring, sleep tracking, step counting and GPS for my hikes and runs (when they start to happen again).

I am particularly bowled over by the auto exercise recognition. I don’t have to tell the watch I’m starting a session, it just seems to know. So my weekly badminton matches get captured and logged for the first time and my daily eBike commute is recognised for its gentle effort.

The one area that I HATE about Fitbit though, is its resting heart rate feature.

This should be such a useful feature for tracking wellness trends and readiness for training but Fitbit have decided to go it alone with the definition of Resting Heart Rate and have created a useless and erratic version that bears no resemblance to a true RHR.

Fitbit resting heart rateYour resting heart rate is supposed to be the lowest heart rate achieved while awake but at rest. So if I look at my HR while writing this slightly ranty blog post and my current heart rate is 64 but my Resting Heart Rate is 74, I know for a fact that 74 is not my Resting HR! My question is why doesn’t Fitbit know it?

This photo from Twitter illustrates the point nicely.

DC Rainmaker wrote an interesting article this week on continuous heart rate tracking and also commented on the disappointing, “conservative” approach by Fitbit to RHR monitoring.

The Fitbit help pages explain how they measure resting heart rate:

Your tracker estimates your resting heart rate by measuring your heart rate while you’re asleep and while you’re awake but still during the day.
For best accuracy, wear your tracker to sleep.  If you don’t wear your tracker to sleep, the tracker will still try estimate your resting heart rate while you are awake.

I find it hard to understand how difficult it can be to record the lowest heart rate while you are awake, especially if you don’t wear it while you sleep. The Fitbit does a very good job of detecting sleep and non-sleep so thats half the job done.

It feels to me as though they are taking my lowest HR during the day and then adding 10 or so beats for the heck of it.

If you haven’t already noticed, this annoys me. Fitbit have taken a fantastic fitness watch and then infected it with a great big flaw. I’d much rather opt for manual recording of RHR while ever their estimates remain so poor.

I do like the continuous heart rate tracking though:

Fitbit Surge continuous heart rate monitoring

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