Interpreting Oura Ring Biometrics: Part I — Readiness

Trevor Hess
Oct 23, 2020
6 min read

Updated: Nov 5, 2020

From writing my previous article, you've probably realized by now that the Oura Ring is certainly great for visualizing what habits positively or negatively impact readiness and sleep scores. However, what truly goes into determining your scores in the first place? — biometrics.

Unless you're a fitness geek like me, or just didn't know that each biometric plays an important part in your overall readiness and sleep scores, then you might not know why your scores fluctuate day-to-day. So I'm going to help you out; in this two-part series, I going to break down each biometric and what their fluctuations mean for your health — starting with your readiness biometrics.

1. Resting Heart Rate

Most people are familiar with resting heart rate (RHR), which is measured as the number of times your heart beats per minute (bpm). You get it checked everytime you go see a doctor and for the most part, the lower it is, the better off you are. A normal RHR for most adults is anywhere between 60-100 bpm, but can be as low as even 30 bpm, depending on fitness level and a variety of other factors. However, I believe that we pay too much attention to RHR as a single value, as is the case at the doctor's office when you might see your value once every few months.

Rather, it's much more important to look at RHR as continuous snap shots over the course of the day. Why? Well for starters, our RHR fluctuates to maintain homeostasis, or balance, in our body depending on what we're doing throughout the day. Take for instance when you're at the doctor's; most people are usually anxious for various reasons, which means your brain is using up a lot more oxygen with all the adrenaline pumping through your veins. So to compensate, your RHR has to increase to supply more oxygen. On the flip side, when sitting down and relaxing after a day's work, you're using significanly less energy, and so you can expect your RHR to be much lower.

But what if you extend those snapshots, not over the course of a day, but over the course of weeks or even months? — that's when you really get to see the changes in your health. Think about when your RHR might be highest during the day; if you're thinking about when you exercise, then you're keeping up with me... I guess great minds think alike.

But you're probably thinking, "I thought it's bad to have a high RHR, so should I not exercise?" It might seem somewhat logical to think that way, but there's also the notion of compensation. By stressing your body, and heart, for brief periods while you exercise, you're strengthening your heart. As a result, when you're resting, your heart is stronger and thus, can pump more blood at once — also known as stroke volume. Since your heart can pump more blood at once, it doesn't have to pump as frequently, which is why a general trend of a decreasing RHR is a good sign your keeping your heart healthy.

2. Heart Rate Variability

Unlike RHR, the higher your heart rate variability (HRV), the better. So what is HRV anyway? HRV is the time in milliseconds (ms) between each heart beat. Most people don't really think about it, but there is a time when your heart isn't beating at all. Either way, HRV is extremely valuable and in my opinion, more accurately represents your ability to cope with stress on a day-to-day basis than does RHR. HRV usually varies anywhere between 10-100 ms, but can be as high as 250 ms, depending on how often you're in a parasympathetic state.

Whoa, whoa, slow down. I know, I know, let me back up a little. Your HRV is usually the highest when you're the least stressed, or in other words, when you're in a parasympathetic state — the opposite to being in a stressed or sympathetic state. Your nervous system can be operating in either state at any point in time. So if I were to ask you again, this time, when your HRV might be lowest, if you guessed exercise, you're still with me. Like I mentioned earlier, if you can stress yourself for brief periods, such as when exercising, your nervous system will eventually compensate and your HRV will be, on average, higher for the rest of the day.

However, unlike RHR, I think practicing how to remain in a more relaxed state has a greater effect on increasing your HRV than does habits that significantly lower it. Personally, taking regular cold showers, meditating, morning walks in the sunshine, and periods of silence all require effort like exercise, but rather train you to resist being stressed and to remain calm instead. So by all means, exercise to improve your RHR, but also try to include habits that challenge you to remain calm in times of stress so that you can develop a general trend of increasing your HRV.

3. Body Temperature

Most people are familiar with body temperature. However, in my opinion, the value of your body temperature, like the average 98.6 °F, isn't as important as the fluctuation from your personal baseline. One person can have a normal body temperature of 97.0 °F, but come down with the flu and have a temperature of 98.6 °F. To another person, this latter value can be their baseline — do you see what I'm getting at?

As a result, the best way to interpret a metric like body temperature is pay close attention to how it fluctuates from your baseline on a day-to-day basis. The best use I've found for body temperature is recognizing when my fluctuation from basline is steadily increasing over the course of several days, which usually indicates I might be getting sick. However, as I mentioned in my last article, that's rarely been the case since using the Oura Ring, as I'm now able to take action sooner to prevent any sort of sickness from progressing.

But one other great use for body temperature is to see your fluctuation as a daily snapshot. The reason being that a decrease from baseline while sleeping can show you're properly cooling down at night, while an increase may indicate your environment may be too hot, or that you simply ate too large of a meal close to bedtime (more on this point in part II). So as a rule of thumb, it's best to remain at baseline, but a decrease is usually always better than an increase.

4. Respiratory Rate

I think it's fitting to talk about respiratory rate last, as I see its trends as a combination of RHR and body temperature, and you'll see why too momentarily. Respiratory rate is measured as the number of breaths you take per minute (breaths/min), with the norm being 8-16 breaths/min. Like RHR, you want to see a general decreasing trend for your respiratory rate, and it can similarly be improved through stressing your body occassionally, such as through exercise. As a result, by paying attention to your respiratory rate over longer spans of time like weeks and months, you can get a general sense of whether you're improving your fitness or not.

The nice thing about respiratory rate though, is that it can also be useful for daily snapshots of time as well. Like body temperature, a decrease in respiratory rate one night might indicate you gave yourself ample time to wind down before falling alseep. Conversely, an increase one night might indicate you ate too large of a meal close to bedtime — you'd be surprised how drastically meal timing can impact your sleep. So in general, aim for a decrease in respiratory rate over larger spans of time, and for daily snapshots, a decrease is usually always better than an increase.

Summary

So that pretty much sums it up for what decides the fate of your readiness score. The amount of data can be daunting at first, but you'll gradually become experienced understanding what biometrics correlate the most to how you feel day-to-day and what habits you can implement to improve them.

In part II, the last part of this two-part series, we'll cover the biometrics of sleep, and be prepared to hold on. If you thought readiness was important, interpreting sleep biometrics can be even more important, if not the most important, way to alter your habits, and ultimately improve your health.