How my fitness tracker tells me when I'm falling ill

A picture of Fitbit's Sense, a fitness tracker, on a wrist.
Fitness trackers can provide a myriad of benefits, one being able to track your heart rate. (Photo: Yahoo Lifestyle Singapore)

One can argue that a fitness tracker is a must for any fitness enthusiast these days.

A decent one helps you track various parts of your daily life, be it the amount of steps, the calories you burn, the length of your exercise and and some even tracks your blood oxygen level.

But there is one feature that I've found extremely useful for myself in four years of using one, and it is my resting heart rate estimates.

Because of this feature, I found something extremely interesting about what it tells me — I am able to predict when I am about to fall ill.

This has helped me take necessary precautions and improve my lifestyle to alleviate most of the illness before it truly hits.

What I initially thought was bro-science (I actually discovered it on my own by trial and error) turned out to be backed up by various studies made by medical institutes.

A study by Stanford University School of Medicine in 2017 researches on the fact that a drastic change in heart rate and blood oxygen levels could be an onset for an illness.

Harvard Medical School even highlights that an increased heart rate is a precursor to illness, but can also be a sign of heart problems.

Coupled with the recent research by Fitbit on using fitness trackers to discover the onset of COVID-19, it is becoming quite clear that having a fitness tracker would help detect an upcoming illness.

So, how do you actually find out that you might potentially be falling sick?

If you own a fitness tracker from the main brands like Garmin, Fitbit or Apple, there will usually be a feature which informs you about your daily resting heart rate in beats per minute (bpm). Do note that this is different from your real-time displayed heart rate.

Your real-time displayed heart rate can vary due to the activities that you perform during the day, so it is not the statistic you want to look at.

The resting heart rate for the day is a static number, usually calculated by different proprietary means, depending on which fitness tracker you are using.

For example, Garmin's resting heart rate is calculated using the lowest thirty minute average heart rate in a twenty four hour period. For Fitbit, they use an undisclosed proprietary calculation method.

Whatever it is, as long as you are able to read your estimated daily resting heart rate, it is more than enough to track if your body is falling ill.

Different people have different resting heart rates, though. Your own values can highly differ from someone else's.

My personal resting heart rate ranges from 67bpm to about 72bpm. As long as my daily numbers fall into this range, I am usually not too worried.

A screenshot of heart rate readings from the Fitbit app.
My own personal resting heart rate ranges from end of May 2022, the last time I fell slightly ill. (Photo: Yahoo Lifestyle Singapore)

But the last time I was close to falling ill, referring to the picture above, the spike in resting heart rate from 27 May to 28 May was enough for me to take some precautions to get my body to rest.

Thankfully it was a weekend at that time, so I ended up relaxing and making sure I had enough sleep.

And just as predicted, I had a mild fever on the 29 (not COVID, don't worry), but I quickly recovered due to the early warning and my body being well rested.

I was fit for daily function again on 30 May, and you will notice that my heart rate stabilised back to its 'normal' values soon thereafter.

This is just a simple example on how your fitness tracker can warn you if you are falling sick.

Of course, sometimes, things may be more serious than this.

An elevated heart rate may point to many other problems, so if you still fall ill after taking all the precautions, or if your sudden increased heart rate persists throughout many days, make sure you get yourself to a doctor for a checkup.

Who knows, it may just be a tracker malfunction, but that would be the best news for any individual at that point.

Whatever it is, one cannot deny that the indication of an elevated resting heart rate can sometimes be extremely helpful for your health. With fitness trackers being much more accessible and affordable these days, it could be a very valid way to keep yourself healthy.

Dominic loves tech and games. When he is not busy watercooling his computer parts, he does some pro wrestling.