Two Smart Watches Angie

Do you remember Two Jags Prescot? I wonder how many
smartwatches he had.

Just over a week ago a friend of mine gave me her Fitbit smartwatch, having upgraded to a newer model. The timing of this unexpected gift could not have been better as I'd just re-enrolled with Slimming World and was looking for inspiration to exercise a little more.

Readers of this blog may recall that I already had a smartwatch. Back in 2018 I bought a Delvfire Fitness Tracker and used it for about a year, before losing interest and reverting to my old wristwatch.  Was it just coincidence that my weight then began to rise above my Slimming World target?

But why would I accept a gift of a Fitbit when I already had a smartwatch? Well, the Fitbit ought to be superior as it cost about three times as much as the Delvfire and it did indeed appear to have better fitness tracking software.  Perhaps, with my love of statistics, that would inspire me to greater fitness.

Before finally consigning the Delvfire to the dusty recesses of some seldom-opened drawer, it would be fun to pitch it against the Fitbit. And that's how I came to wear two smartwatches for a night and a day – the Delvfire on my right wrist (blue strap) and the Fitbit on my left.

I've never been over-keen on monitoring my sleep and prefer not to wear a watch in bed. As long as I get about 7 hours sleep on most nights, I'm happy. However, the nighttime data from the two watches did make very interesting reading.  You may need to click the images to get a clear view.

The Delvfire data (left) is a lot less detailed, and credits me with 1hr:2min more sleep and considerably more deep sleep than the Fitbit. Indeed, it's quite difficult to correlate the two graphs, though both do show a more broken sleep pattern from about 6am. In truth, I did wake up about then, and spent some time lying awake before drifting off to sleep again and being woken by my alarm clock. So I'm inclined to believe the Fitbit and dismiss the Delvfire as little more than a rough approximation.

I also like the Fitbit's ability to detect REM sleep, when I would most likely be dreaming. And yes, I was dreaming just before being awoken by the alarm clock – I seem to recall standing alone in the garden, feeling cold and wondering what one of my cats was doing in the greenhouse!  Sadly, the Fitbit seems incapable of interpreting this great mystery.

After breakfast the sun was shining and the Met Office weather app assured me that it would stay that way. What better than a 4 mile walk in the Forest? Unfortunately, on this occasion the Met Office were very, very wrong. Not half an hour into the walk the skies blackened and it began to rain heavily. I pressed on for a while but with no sign of a break in the clouds, briskly retraced my steps home.

The Delvfire (left) has recorded more steps and an extra 0.1 miles, but that might just be because I was wearing it on my right wrist. I'm right-handed and perhaps jerk it around a bit more.  The huge difference, though, is in the number of calories burned – 247 on the Delvfire, 901 on the Fitbit.  According to an Internet site I accessed, I would expect to burn about 300 calories when sleeping. I burned another 300 during my brisk walk (according to the Fitbit), so by any measure the Delvfire figure is seriously low.  But 900?   It was time to look at heart rate.

Both show the result of that quick walk home in the pouring rain. Somewhat illogically, though, the Delvfire's y-axis starts at zero. I sincerely hope that I don't record a heart rate that low any time soon! By starting with a value of 40bpm the Fitbit certainly wins on clarity. Whether my average heart rate should be 57bpm (Delvfire) or 54 (Fitbit) I know not.

What's really impressive with the Fitbit, though, is that, without being prompted by me, it has detected the start of my walking exercise and recorded it separately – 303 calories burned in 61 minutes, with 11 minutes of 'cardio' quality exercise. I must strive to be caught in downpours more often.

I conclude that the Delvfire's data is little more that an approximation, though it's still a good incentive to exercise and the longer-term trends would be of value.  For its price, it's a reasonably good fitness tracker. I reckon that I've shown, though, that the Fitbit is an altogether more accurate device. Moreover, the clarity of its data presentation is more than sufficient to keep me enthused.

And guess what?  I've even continued to wear it in bed.