❮   all STORIES

Health Metrics: What vital metrics are important to track? And why?

For some time now, tracking is not only reserved for professional athletes anymore. With the growth of consumer wearables, we've seen a lot of tracking devices flooding the market, consumers becoming confused about their benefit and their use.

But this is not the fault of consumers, it is the fault of brands that do not educate consumers about the tremendous potential of these devices.

So why do more and more individuals start tracking their biosignals? Quite simply because tracking is a tool that gives a true advantage in your journey to good health and energy gain.

Let me explain. Some people think, “Why shoud I wear something that's going to tell me how I feel if I can just feel it?” Well, feeling is tracking. Feeling is the most commonly used method for tracking. But tracking isn't just about how you feel; it's about understanding and quantifying what's happening to your body before you even start feeling it as your body and mind unconsciously adapts to many external and internal stressors.

Did you know that with some second generation of wearable tracking devices that track certain key metrics you can know if you are getting weak before the symptoms of an illness appear, that you can track your energy, your menstrual cycles, your physical and mental recovery, stress, and many other things?

Here is the ultimate goal of tracking; learning about the effects that external and internal stressors have on your body & mind: the effects of your activities on your health, the effects of your activities on your sleep, and the effect of your sleep on your productivity and health. 

Tracking is a virtuous circle that allows you to learn about yourself in order to make smarter actions towards your goal while improving your lifestyle.

But what should you track?

Well, there are several key health indicators that can be tracked daily. All these metrics correlated together will make incredible predictions about your health.

Subjective Evaluation

Basically, it’s listening to your body. Obviously, your subjective evaluation is very predictive of your current health and energy. Did you sleep well? Are you tired from yesterday? Starting to feel a little sick? Ready to tackle great challenges? Those feelings are important to assess every morning and will put you on the lookout for what you can improve.

Now let's move on to what you can't feel.

Heart Rate Variability

Heart rate variability (HRV) gets a lot of attention nowadays. It has use for athletes to optimize their training, for people wanting to reduce their stress and check on their overall wellness and is studied globally for its correlation to our autonomic nervous system. HRV measures the specific changes in time (or variability) between successive heartbeats. The time between beats is measured in milliseconds (ms) and is called an “R-R interval”.

A healthy heartbeat contains healthy irregularities. If your beats per minute is 60 for example, your heart will most likely not beat once every second for a whole minute. It will rather have different interval lengths between each heartbeat. One interval could be 0.75 seconds for example and the next one could very well be 1.25 seconds.


The fitter you are, the more your heart must be able to adapt to any situation, to accelerate as well as to slow down, that's why your R-R interval will be irregular. If it is more regular it means that you are out of shape and that your heart will not be able to easily adapt. 


Circular uses RMSSD calculation which is the root mean square of successive RR interval differences that will give you an easier score number to study. HRV naturally decreases during a negative stressor. Thus, the higher the score the better you are, the lower the score the less healthy you are. But beware, HRV scores are personal. Everyone has an average HRV. And you should compare your daily HRV to your average (long term) HRV. If your daily HRV is above your average HRV you’re good, if below you’re less good.


If you want to learn more about how to improve your HRV baseline, click here


Resting Heart Rate 

Resting Heart Rate is the heart rate when the body is in a state of complete relaxation. It has been widely studied by scientists and it has shown that a low resting heart rate is correlated with a higher life expectancy, higher overall wellness and a reduced risk of developing cardiovascular diseases.

The fitter you are, generally the lower the Resting Heart Rate. This is due to the heart getting bigger and stronger with exercise, and getting more efficient at pumping blood around the body, so at rest, more blood can be pumped around with each beat, therefore fewer beats per minute are required.

The RHR evolves according to your gender, age, and health, here is a summary table of the averages RHR for healthy individuals.

If you want to learn more about how to improve your RHR baseline, click here


Well-being is the result of a complex equation whose first main 3 factors are physical activity, rest and nutrition. Here we deal with rest, of which sleep is a large part.

Sleeping is such a daily and frequent moment that the majority of us forget its importance. When your schedule gets busy, sleep is often the first thing to get neglected. However, it has been proven that losing even one hour of sleep during a night can affect your mood, your energy, your mental sharpness, your cognitive ability and ability to handle stress. 

Speaking of feeling, when we think about sleep, we might instinctively think that our body and our mind are kind of shut down. Just because you're resting, it doesn't mean that your body is resting too. On the contrary, your body and your mind work hard during sleep.

Sleep is the period to repair, regenerate and prepare your mind and body for performance. Deep sleep enables physical recovery while REM sleep helps with memory, thinking, and creativity.

Many people may not even remember what it feels like to be truly wide-awake and fully alert. Your sleep is a reflection of your stamina during the day. No other activity delivers so many benefits with so little effort! 

So track your sleep each night and trends over time, understand your sleep and learn about the parameters that impact your sleep quality and how it correlates with your days, build better habits for better rest and even wake up during light sleep stage with energy thanks to a silent & smart alarm clock.

If you want to learn more about how to improve your sleep, click here

Physical activities

The second factor of the well-being equation. You can track your steps, distances, your calories, the duration and type of your sport session. That everyone knows from now on.

We will see how knowing your Maximum Heart Rate and tracking your Heart Rate during exercise can give you a competitive advantage over your fitness goals.

Getting the most out of training doesn’t always require working harder: it requires working smarter. Quantifying your physical activities and using a heart rate training range will optimize your effort.

Once you know the value of your Maximum Heart Rate, you can determine your target heart rate zone for your exercises. By exercising in the target heart rate zone, you can get a better idea of the intensity your heart provides during work and organize your exercise program more accurately. There are different zones for different goals, strength, endurance, weight loss? You have better vision and control.

Moreover, by correlating the data you can know your active minutes, activity volume and recovery time.

If you want to learn more about how to track your activity, click here


Now you know that you should track sleep and the calorie loss. But is it useful if you can't track calorie gain? With nutrition, you complete the combo. A lot of apps do this now, you can easily log your diet by taking a picture and correlate it with the rest. Depending on your objective you will know if you should do more sport, eat more, do less sport or eat less. As simple as that, don't bother directly with the different diets and nutrients unless you're sure about what you're doing.

Oxygen Saturation

Pulse oximetry is a method doctors use for rapid assessment and monitoring of a patient’s respiratory function. It may be used to monitor the health of individuals with any type of condition that can affect blood oxygen levels. You might correlate blood oxygenation to sleep apnea events (sleep disorder in which breathing repeatedly stops and starts). The good news is that it can be a great indicator and reflects these events well. 

Oxygen saturation is also a key factor in performance if you live or train at altitude, or tend to overtrain. Using SpO2 readings with your usual training metrics can, first and foremost, help you gauge whether you’re recovering properly.

Correlate your RHR, HRV, and SpO2 after training days to see where your recovery is. Paying attention to the right numbers can result in a good training block and even help avoid an over-training.

If you want to learn more about SpO2, click here

Body Weight

There is no need in measuring your weight daily, but it can be a useful metric on long term objectives. Weight gain could indicate water retention and inflammation. Excessive weight loss could be due to inappropriate nutritional fueling. Both are undesirable.

Temperature variation

The variation of your temperature and its trend on a larger scope is a very interesting metric. 

It is an essential metric to evaluate how your natural defenses respond to your environment. 

When the variation is higher than +/- 0.5 degrees Celsius, that’s when you need to start paying attention. An advice would be measuring your body temperature with a thermometer. 

Any variance above or under your baseline (that is your normal temperature) can give a lot of crucial information. It can fluctuate with activity, your nutrition, your circadian rhythm, can indicate that your body fights against an illness, can reflect external environment changes such as a season change and can even reflect a woman’s menstrual cycle very clearly.

If you want to learn more about how to track your temperature variation, click here

DNA & Blood Tests

DNA test will teach you a lot about yourself, what you do or don't need, what you can and cannot eat. 

It can't be harmful to have a blood test at least every year to see if you're missing or having too many nutrients: iron, magnesium, vitamins, etc…

How to track all these metrics?

You can track these metrics with several specialized and precise devices for a particular metric or try to have a device that will track the vast majority of them and that will synthesize for you the correlations of all these metrics. That's what we do with the Circular smart ring.

Circular calculates your energy levels based on many physiological contributors: Physical Activity, Sleep, Heart Rate Variability (HRV), Resting Heart Rate (RHR), Temperature variation, Blood Oxygen Saturation and Breathing Rate (BR). These metrics are calibrated to your baseline, which means that your scores are personal to you. Moreover, a personal assistant will make the data correlation work for you and provides you with personalized recommendations when there are noticable occurence.

You can also read the post about The Circular® Global Score, Leaderboard and Streak score: improve your wellness ludically.

Laurent Bsalis

Laurent is passionate about biohacking and tries his best to be a better version of himself. He also eats too much ice cream which is a problem.

You might also like