Testing the Oura ring

What is non-wear time and how is it used by the Oura ring?

I was curious about how the Oura ring was tracking my daytime activity. Workouts that I found strenuous were being captured by the ring’s activity algorithms as low intensity. Other users have noticed this issue and suggested that it is because the ring does not collect heart rate nor respiration during daytime activity. They suggest just taking the ring off during workouts and then manually entering the activity. But, I wanted to know more about how that non-wear time was used in the activity calculations, so I did a small test yesterday.

I wore my ring the previous night and kept wearing it the next day without taking it off to charge.

At 1:22 pm I synced my ring and looked at the activity. As seen in photos 1 and 2, it said 2 hours 54 minutes inactivity, so far that day. I closed the app, took off the ring, and put it in the pocket of my pants. From 1:30 to 2:30 pm, I did a strength and balance workout, including stretching, jumping, lunging, skating, and walking - lots of large arm and leg movements. My heart rate and respiration were definitely elevated.

Photo 1

Photo 2

At 2:31 pm I synced my ring and looked at the activity. As seen in photos 3 and 4, it said 3 hours 39 minutes inactivity. So, the 1 hour and 9 minutes of non-wear time was recorded as 45 minutes of inactivity and 24 minutes of low intensity activity.

Photo 3

Photo 4

It makes sense that the accelerometer and gyroscope of the ring can recognize activity whether it is on your finger or in your pocket. Wearing the ring does not close a circuit. The ring just tracks movement. Its algorithms, however, consistently underestimate the energy expended. I think this is true whether the ring is on your finger or in your pocket. I put it in my pocket just to see whether the accelerometer would work with the ring not on my finger.

At 3:13 pm I manually added the workout activity to the app.

At 5:09 pm I synced my ring and looked at the activity. As seen in photos 5 and 6, it said 4 hours 49 minutes inactivity. I closed the app, took off the ring, and set it on the table.

Photo 5

Photo 6

At 5:49 pm I synced my ring and looked at the activity. As seen in photos 7 and 8, it said 5 hours 2 minutes inactivity. So, the 40 minutes of non-wear time (sitting on the table) was recorded as 13 minutes of inactivity and 27 minutes of non-wear time.

Photo 7

Photo 8

At 6:05, after a brief walk around the house, I looked at the activity again. Photo 9 shows that the activity graph does not make clear exactly how that 27 minutes of non-wear time is used when calculating energy expended. The graph of activity intensity makes it seem as though the 13 minutes of “inactive” time was counted as very low intensity activity and the 27 minutes of “non-wear” time was counted as inactive. Clearly, the graph is not scientific quality, just a visual aid. (See my February 19, 2019 post on this problem.)

Photo 9

My conclusion matches that of other users: the ring is only a general activity tracker. It is not a pedometer nor a calorie counter; “steps” and progress on activity goal “calories” are calculated using algorithms, not direct measurements. This is true for all activity trackers, of course, so buying a tracker is not just about hardware, it is also about accepting the company's algorithms. The balance of activity and rest on Oura is probably accurate to within +/- 30% for time spent and energy expended. There have been a lot of improvements in the ring over the last 2 years, perhaps it will improve in this area, as well. Users who are concerned about tracking MET minutes should enter workouts manually. I think Oura’s current activity tracking will be sufficient to assist with self-monitoring of readiness and health, given the precision of the sleep tracking (including RHR, HRV, temperature, sleep stages, etc.).

Update 3-8-19: I have been corresponding with a representative from Oura. He says, "There is a transient bug in the on-finger detection…” He says that Oura is working on a fix.