Wearables: Meet WHOOP and Oura Ring


This post will go into detail on the wearable technology that I've been using for the last eight months. We all know how much fitness trackers have taken the world by storm. Many of us have a FitBit or smartwatch on our wrists. These are wearable indeed, but they don't do a great job enhancing your quality of life - unless you're obsessed With step counters. Step counters an ambiguous measure of activity (what the hell is a step?). I believe most mainstream wearables are dopamine drips in the form of vibration notifications. Studies show that even feeling the vibration of a cell phone breaks concentration and takes up to 20 minutes for attention to settle back onto the task at hand. The devices I've been using are much less obtrusive as their primary purpose is data collection to improve the quality of life. I want to introduce you to the next level of wearable technology WHOOP and Oura Ring!

What does Whoop and Oura Track?

In the following sections, we will define what data the Whoop and Oura keep track of. I'll then get into their specifics including their proper use - you don't need to wear both of these devices as there is significant overlap. As an engineer, comparing similar biometric data from similar devices was too good to pass up.

Readiness / Recovery Data

Resting Heart Rate (RHR):

RHR is measured in beats per minute (bpm). For most of us, we've all had some exposure to our individual RHR as most wearables track this metric. RHR is a relatively stable metric to show cardiovascular fitness. For the average adult, RHR ranges between 60 - 100 bpm.

Heart Rate Variability (HRV)

HRV is a measure of time between two heartbeats. Many of us compare the human body to a machine, but the time between pulses is not constant regardless of BPM. HRV is measured in parts of a second, or milliseconds (ms).

For anyone who wants to experience it: gently place one finger on your neck or wrist and find your pulse. You should feel longer intervals during each exhale, and shorter intervals during each inhale.

Understanding the Nervous System and HRV

First, we need to understand some nervous system basics. The autonomic nervous system (ANS) regulates systems in our body, such as heart rate, respiration, and digestion. There are two branches within the autonomic nervous system: parasympathetic (rest) and sympathetic (activation). The ANS controls Heart Rate Variability.

Parasympathetic regulation lowers heart rate from the intrinsic* level. A lower heart rate means more time for variability. This regulation affects a few beats at a time. Sympathetic regulation elevates the heart rate from the intrinsic level. A faster heart rate means less time for variability. This regulation affects several consecutive heartbeats.

*Term: Intrinsic Heart Rate - The condition in which neither parasympathetic or sympathetic regulation is present.

Whoop Recovery Overview

Whoop Recovery Overview

Oura Readiness Overview on App

Oura Readiness Overview on App

This encompasses the general rule of HRV:

When the resting heart rate is lower, HRV is higher. When resting heart rate is higher, or during states of stress, HRV is lower.

The range of HRV can be measured anywhere from less than 20 ms to greater than 100 ms. Also, HRV is highly personalized. If someone has a high HRV, that person may have a predisposition, such as genetics, giving them a higher HRV. The only way to understand your HRV is through measuring HRV over time and observing what it affects.

How to use HRV?

Heart Rate Variability provides us with a clear understanding of how stressed the autonomic nervous system is. Measuring HRV means we get a look at how the body is responding to stress in any form. For example, let's say your HRV drops sharply from the previous day. It's worth reflecting on what you did differently that day, both physically and emotionally. For both the Whoop and Oura devices, HRV is measured during sleep. The average HRV is calculated the next day, and the data is stored for future comparisons. We can use this data to determine how well our bodies rested after what activities - see examples.



An easy example is drinking more than two beers before bed (within 2 hours of bedtime). Most often, we see an impact on HRV the next day. Another adverse effect on HRV is pushing the body beyond its tolerable limit, such as a marathon.


Mindfulness practices have shown to impact HRV positively. This objective data gives mindfulness practices significant efficacy. (Study)

HRV is an expanding cardiovascular diagnostic tool that is gaining more recognition and power as technology improves. To be clear, this is an HRV crash course, not an end-all-be-all scientific journal. Be sure to check the HRV related links at the bottom of the post for more information.

Respiratory Rate (RR)

RR is the measure of breaths (an inhale followed by an exhale is one breath) per minute. RR has less daily fluctuation than RHR or HRV. In general, this metric will show how well training routines have improved over the long-term.

Body Temperature (Oura Only)

Body temperature is a reliable measurement of current health. If you're getting sick, you'll see a deviation from the norm. Body temperature also tracks menstrual cycles. In the Oura ring, it is automatically checked at night.

Sleep Data

Total Sleep Time

The total time asleep from all stages of sleep:

  • Light sleep - The first stage of sleep - makes up roughly 50% of total sleep.

  • Rapid Eye Movement (REM) sleep - is vital for re-energizing your mind and body. This stage is associated with memory consolidation and dreaming. REM sleep ranges from 5 -50% of total sleep. An average adult will receive 20-25% of REM sleep each night.

  • Slow-wave sleep (SWS or Deep sleep) - Is the most restorative stage of sleep. This is when the body is busy repairing its cells and tissues. It is also the most challenging stage to awaken from. SWS accounts for 0 - 35% of total sleep. On average, adults spend 15-20% in a deep sleep each night.

Time In Bed

Time in bed includes time awake, as well as total sleep time. Another term for this is sleep opportunity.

Sleep Efficiency

Comparison of time asleep vs. time awake. Sleep Efficiency of 85% or higher is excellent. It is worth noting that sleep efficiency consistently above 95% may be an indication of inadequate total sleep.

Disturbances / Restfulness

These are times you woke up at night. Most of the time, you won't remember waking up, but luckily it can be tracked.

Sleep Latency

Sleep Latency is how long it takes to fall asleep. Sleep latency shouldn't take more than 15 - 20 minutes. If you fall asleep in less than five minutes, this can be an indication of inadequate sleep.

Whoop Sleep Overview

Whoop Sleep Overview

Oura Sleep Overview

Oura Sleep Overview

How Recovery Data and Sleep Come Together

For both devices, recording all of the data described above during your sleep. The devices then aggregate all of the data and put in an easy to understand package. The package is labeled as recovery displayed on a scale determined by each company. For WHOOP, is on a percentage scale. For Oura, it's on a unitless number from 0-100. On the surface, there isn't much difference between the two. WHOOP seems to swing more heavily, meaning low recovery, below 33%, is not uncommon or bad per se. Where the low readiness on Oura is below 60. For me, Oura is more conservative on your readiness say that if you get a readiness of 0, you are likely to be dead (kidding.)


For Oura, the activity goal is based around your readiness with the number of activity calories needed for that day. The range can be from 300 - 650 depending, but overall the ring is not designed to track fitness activities well.

Activity Overview

Activity Overview

Strain (Whoop)

Whoop measures the cardiovascular load on a scale from 0 -21. The scale is logarithmic meaning that getting from 4 to 10 is not a linear progression. In a recent blog post, Whoop went in more detail on the history behind the scale, which is based on the Borg scale. The theory behind is any strain can be multiplied by 10 to get an estimated heart rate for the duration of the activity or day. As an example, if an activity is rated 10, that means the average heart would be measured at 100 bpm.

The usefulness of this scale allows you to get a feel for the perceived exertion for a given workout. Along with the recovery, metrics explained above enable a person to have a look at the amount of stress you can put yourself under for a given day. On top of this Whoop has released its 3.0 version which has added a strain coach. The strain coach allows you to monitor your strain in real-time and what is the optimal strain for that workout.

Strain Overview

Strain Overview

Strain Coach In Action

Strain Coach In Action

Strain Coach Live

Strain Coach Live

What is the usefulness?

At this point, I may have thrown too much at you to want to dive in. It all seems like a lot of numbers and math, right? Both systems are intuitive. Wearables to me are about improving the quality of your life. I am reminded of a quote often attributed to Peter Drucker, "What gets measured gets managed." Part of my motivation on getting Whoop initially, I had heard of both HRV and wanted to learn more about what the metric could be used. The other aspect was better to sleep tracking that informed daily recovery. The average adult gets around 6.5 hours of sleep a night.

Whoop has a sleep coach embedded into the software where it calculates your sleep need depending on factors such as sleep debt, activity, and naps. The sleep coach is a powerful tool while geared heavily towards athletes, but also for the average person who wants to perform better. The idea that you'll sleep when your dead is entirely counter to what science is telling us about the necessity of sleep to improving quality of life. The first step is understanding where you are. I had over assumed how much sleep I was getting before I've tracked it.

Other benefits include behavioral changes; Whoop particularly has a subjective questionnaire each morning. These questions give you some insight into behaviors that positively or negatively affects sleep quality some of these I alluded to in understanding HRV. For full disclosure, I more actively avoid alcohol. Especially later in the evening as I know have more than two drinks within two hours of bedtime with affect my recovery and performance for the next day (I don't want to see low recovery!). While in itself, it is not wrong to be in red and enjoy life, it is just adding more nuance to understanding the choices we make and how they affect the body.

Whoop Sleep Coach

Whoop Sleep Coach

Whoop Sleep Questions - Asked each Morning

Whoop Sleep Questions - Asked each Morning


As I am writing this, it may be clear that for my use case, I'm getting a bit more value from what Whoop's platform is providing and for the most part that is the case. As I mentioned, Whoop is designed for the athlete in mind looking to build strain and push themselves to their limit. The band itself is very comfortable, waterproof and charging method that means you don't have to take it off. In a single word, it's sleek. Battery life for Whoop 3.0 is now up to five days which up from about two from the 2.0 version. The payment model is $180 for six months service (they subsidize the cost of the hardware for a subscription model) and $30 for each month afterward.

The Oura Ring, on the other hand, is more for the general user looking to gain insight into the sleep. While not as robust in the activity front, it will still help guide you. Also embedding this degree of sensors into the shape of a standard ring is no laughing matter and has a weeks work of battery life. The ring itself is also waterproof. The ring is a flat $299 with 2 - 3 weeks lead time as you do have to size the ring.

I think your choice is going to depend on your lifestyle and choice of how much you want to spend is limiting factor here.

Thinking to the Future

Some of you may be wondering at this point why do have both of these wearables? Well, it is just for that reason; I chose to support them because they are part of the world that I believe can help more than just me. I don't have a clear winner in my eyes as I do use both regularly and they do have some differences in measurement that I find interesting, but that is for another post.

The more I use these wearables, the more I hope that technologies in these forms enter into healthcare for those who aren't intrinsically interested such as myself. I can envision a world where a doctor can prescribe sleep monitoring as the first course of action. Get a baseline for the patient's behaviors are and make adjustments at the lifestyle level rather than using a pill to circumvent that. Wearables of these kinds can have impacts that allow patients to have more control of understanding why they should make a change instead of being told to make a change. When they see a difference and feel the change, it becomes that much more reinforcing.

A Deeper Dive

This is not the last you'll hear of my wearables. I wanted to give an overview of the new class of wearables that provide much more nuance in how well your body is recovering from the stress of life. You'll get more on what trends I've noticed in myself and tips to improve your own life specifically in creating a better sleep routine!

Much of this exploration has been spurred by reading the book Why We Sleep by Matthew Walker. I encourage you to read that book it will change your mind on why sleep is so damn important.

At the very least listen to his TED talk Sleep Is Your Superpower

If you become obsessed with his research, listen to this series of podcasts with Peter Attia with over 6 hours of audio!

For more on HRV:

Check out some more detail from Oura - HRV Basics

Listen to the Whoop Podcast that is more in-depth on what you can learn about HRV

Finally, more look into strain check out this short blog and this podcast from WHOOP.

Find out more about these technologies at their websites! WHOOP and Oura


About the Author:

EW Grad.jpg

Erich Wenzel has a degree in Electronics Engineering Technology degree. He works as a Test Engineer for a third-party testing facility in the certification, inspection, and testing (CIT) industry for the last five years. While pursuing his degree, Erich has worked full-time at his position allowing for a unique perspective of one foot in the engineering and academic world. 

Outside of the working world, He became interested in the optimization of the human body. He is asking the question of what can I do to allow myself to function better in any aspect. Erich has a deep fascination in how the body works from strength and flexibility to psychology — seeing his routine and life as an experiment.

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