Earlier this year my employer provided us with the opportunity to do a three-day Firstbeat Lifestyle Assessment. This provided me a chance to do three days of “double self-quantification”, and compare the results of the much hyped Firstbeat to my daily driver, the Oura ring. I’m not going to explain how these devices or the Firstbeat service itself works, but let’s just say they both heavily focus on Heart Rate Variability (learn more from Oura’s and Firstbeat’s HRV info pages).
These devices are known for sleep and recovery tracking, but they also measure the wearer’s activity throughout the day. This first part of the comparison focuses on that: Firstbeat’s and Oura’s activity analysis differ quite a lot in the ways they capture your activity and what markers they use when doing so.
Firstbeat uses “a combination of heart rate, respiration rate derived from heart rate variability, and a third variable provided by the Firstbeat analytic engine that allows the model to reliably detect current oxygen consumption as it corresponds to the intensity of your physical activity.” On top of that, the user manually marks their exercise times to the mandatory wellness diary. I thought this manual entry would be a way for Firstbeat to verify the reason for your raised heart rate to be exercise and not something else, but as we’ll discover later, that’s not necessarily the case.
Oura relies mostly on “extremely sensitive 3D accelerometer” – so in other words, your hand movement – but they do combine your height, age, weight and sex to produce the final estimates of physical activity, energy expenditure and number of steps taken (more on steps in a moment). Not ideal, but honestly, it’s probably the best you can expect from a ring. Oura doesn’t have on-demand HR monitoring, but you can still manually input any workouts you’ve done in order to get accurate calorie burns for those periods at least.
Before delving into the results, here’s a short summary of the three days that were tracked. This is important to know as it gives context to the results:
- Friday: Normal office day. Only a 30-minute resistance band session, as I was recovering from unusually strong and early pollen season. Sauna in the evening.
- Saturday: Drove/sat in a car for about 6 and a half hours. 3 portions of alcohol during the day.
- Sunday: 1-hour sessions of bodyweight exercise and yoga. Sat at the computer the evening.
Daily Burned Calories
Right of the bat, we can see that Firstbeat estimates my daily calorie burn to be way more than what Oura does. On average, Firstbeat’s results were 21.58 % (or 736 kcal) higher, and for Friday’s data the difference was a whopping 32.65 % (or 1,187 kcal)!
Of course, Firstbeat claims that their results are “accurate within 5-7% of laboratory measurements” and I’m sure continuous heart rate monitoring has an edge in this matter, but the difference is way bigger than I had expected. This one was definitely a key takeaway for me.
At least the general trends seem to align between the two platforms: Saturday was my least active day and Sunday was the only day I did heavy exercise – as burned calories clearly indicate.
Calories Burned During Exercise
Limiting the results only to exercise, the comparison happens between Firstbeat’s “vigorous & moderate physical activity” (>40 % of maximal capacity) and Oura’s “activity burn” (the portion that exceeds 1.5 MET level). These are clearly two very different ways of calculating the calories burned by exercise, but the following results do provide some backdrop when we take a look at where (or when during the tracked days) the differences in the results come from.
As expected, Firstbeat’s results were again higher, averaging 37.50 % or 243 kcal more than Oura’s activity burn. However, the difference was only 4.71 % or 62 kcal during Sunday, which was the only day I performed actual rigorous exercise. Note that I did manually log the exact number of burned calories from my exercise to Oura. Of course, three-day sample size is clearly the limiting factor here, but it’s good to know that if you manually log your exercises, Oura can do a pretty good job in estimating your basal metabolic rate (BMR).
To be exact, on that Sunday I walked to the gym, did a bodyweight workout for an hour (644 kcal), yoga for another hour (313 kcal), and then walked back home. These calories were measured with Polar OH1 and then logged to Oura. In total that would be 957 kcal for the two hours I spent at the gym, but in my Firstbeat Lifestyle Assessment report, they’ve lumped together not just those two hours, but presumably also my walks to and from the gym (the report doesn’t clearly indicate the timestamps to what Firstbeat considers an exercise), totaling the burn to 1471 kcal. On their arbitrary 1-5 scale, Firstbeat ranked this exercise period to have a training effect of 3.2 (“improving”), which does correlate with Polar’s assessment of the bodyweight workout, but not with their assessment of the one-hour yoga session that followed.
So why did Oura’s BMR differ so much from Firstbeat’s estimations during the first two days of measurement? Didn’t I just claim that Oura might be doing a pretty good job with BMR? Analyzing the results, I believe the differences are inevitable since Oura has only your hand movements as a variable data point. For example, commuting to work with a bicycle burned between 238 and 347 kcal (that’s to and from the office on Friday, again unclear what exact times does Firstbeat think that “exercise” started and ended). Although Oura did caught some of that hand movement/vibration, it still estimated that the activity burn for the whole day was just 369 kcal – and that includes also 30-minute resistance band session and walking to and from the lunch place!
So in a summary, Oura does have a pretty good hunch on your daily activity, but without HR data to back it up, it has troubles estimating the actual intensity of the said activity. Also, good to remember that the inevitable charging periods are going to register as zero activity in Oura’s log.
All of this is to be expected, as Oura’s primary function is to track sleep. However, as tracking activity levels is an important part of the way they analyze your readiness and recovery, I think it makes sense to take a critical look at this aspect of the ring as well.
In my opinion, daily steps taken is not an important or even an interesting data point. Perhaps if you’re just starting your road to a healthier lifestyle or you’re recovering from an injury, then maybe tracking the overall trend of steps taken can be useful. By the way, did you know that “10,000 steps a day” thing does not come from science at all, but instead from the name of a pedometer sold in 1965 in Japan called Manpo-kei, which translates to “10 000 steps meter” in Japanese?
Anyway, with steps taken, the results turned upside-down: this time Oura consistently reported higher numbers. On average, I took 8618 or 2145 steps according to Oura and Firstbeat, respectively. That’s a 75.85 % difference in steps taken.
If anything, this made me trust any pedometer readings even less. Sure, we’re talking about devices that were on my finger and chest, not attached to my feet, but still. In the end of the day, I still wouldn’t put much value on the amount daily steps taken.
It’s not a shocker that Firstbeat Bodyguard 2, a device that tracks your heart rate 24/7, gets a vastly different (and most likely more accurate) results than Oura ring, which tracks your activity mostly based on an accelerometer. In all fairness, with today’s technological limits, that’s probably the best we can get out of a ring form factor with a seven-day battery life. As a last comparison, I leave you with the activity scores from both platforms:
__________Fri Sat Sun
Firstbeat 67 21 100+
Oura 64 53 75
All in all, during the tracked days I wasn’t particularly active, and I wouldn’t consider them to be a representation of normal three days of my life (but then again, what three days would truly be).
In the next part of this comparison, I’m going to look more closely the sleep scores: length and quality of sleep, lowest resting heart rate, average HRV during the night, and generally how the two platforms rated my sleep. I’m expecting the results to be much closer to each other, as this is the area both claim to excel. We’ll see.