on-going mostly unedited stream of thoughts

biometrics pre, during & post-covid

A couple of weeks ago I received a notification from my apple watch that there were some new health trends from the health app:

screenshot of apple health app showing my average resting heart rate has increased in the last 20 weeks
screenshot of apple health app showing my average cardio recovery has decreased in the last 15 weeks

Obviously this is because I had covid: being sick itself and recovering from the illness has caused my heart to work much harder, and also because there is some deconditioning due to not doing much cardio exercise post-covid because I did not want to risk long covid.

Apart from apple’s default background monitoring I also do active daily monitoring of my biometrics because of my chronic migraines. Most of the time I don’t have a good sense of whether my body is stressed – actually most people probably don’t, athletes use similar tools to gauge the intensity of their training too, that is why these tools exist – so I have to actively monitor my biometrics to get a gauge on how much I should avoid stress that particular day.

These are the biometrics relevant to this post that I am measuring, among many more:

explaining morning measurements and orthostatic intolerance

Marco Altini, the founder of the hrv4training app explains in this article the difference between sleep and morning measurements for hrv. More importantly, he explains why we should take our morning hrv while sitting or standing:

“sitting or standing HRV represents cardiac autonomic nervous system activity in response to physiological stress (orthostasis) with a strong influence from the baroreflex. The physiological challenge exacerbates your response so that if something is off (there is more stress, sickness, or anything else), there will be a much larger change in HRV (and resting heart rate) with respect to the change you would see if you are lying down (sleeping or in the morning).”

Heart Rate Variability (HRV) measurement timing: morning or night?

Basically, it is more stressful for the body to sit straight or stand versus lying down (duh), so this stress will show up in our heart rate variability. This is actually exceptionally important in the context of this post and post-covid recovery because covid is known to induce orthostatic intolerance, which is the inability to cope with this stress of sitting and especially standing. Serious cases of orthostatic intolerance will result in postural tachycardia syndrome (POTS), which makes people unable to tolerate standing for even mere seconds without risking fainting spells.

People can potentially monitor their capacity for orthostatic stress post-covid to decide whether they should return to their normal routines or actively recover more. It is common for athletic people to trigger long covid because they returned to exercise too soon. I often wonder if they could have avoided this if they monitored their biometrics closely. Can people avoid post-covid cardiac arrests and strokes too if they wear a monitoring device?

Covid aside, monitoring our response to orthostatic stress can prevent the negative effects that comes from overloading our bodies beyond a certain threshold, such as exercise injuries, chronic illness flareups, overtraining syndrome, etc.

my biometrics pre, during, and post-covid

Thankfully, apart from a fainting episode and a few episodes of very elevated heart rate, I didn’t develop POTS from my infection. However, I did notice a decreased ability to cope with orthostatic stress. I thought it would be interesting (perhaps only to me lol) to compare my biometrics before covid and post covid:

screenshot of a table showing my pre and post covid biometrics
biometrics are averaged across a specific duration, “after” indicates the same time period right after testing negative, “recent” is roughly 100+ days post-infection

From the above table we could see that in the grand scheme of things the infection didn’t affect my resting heart rate during sleep too badly, which is fortunate because having the capacity to somewhat still relax during sleep was probably key to recovery. But it was the morning biometrics which measured the impact of orthostatic stress that suffered the most. Those were from just sitting down with my back straight up without support. For many mornings simply standing would send my heart rate to 100bpm+. It is much better now – 121 days post-infection as of today – but I still get erratic readings once in a while, whereas pre-covid my heart rate was stable.

Drink copious amounts of salt water would help, but recently I realised that my blood pressure is elevated with the increase in blood volume. So it feels like I have to pick either a faster heart rate or an elevated blood pressure. I am picking the normal blood pressure for now in favour of an increase in heart rate, and hopefully the ability to return to cardio exercise will improve my heart rate. I use my biometrics to plan my exercising. Once they show continued stress I will take steps to actively recover. This will allow me to avoid developing some form of chronic stress on my body.

The lessons here

I can imagine someone having an oura ring or similar and thinking they have recovered to their baseline because it only measures biometrics during sleep. Or most people don’t have any such devices. They feel fine, so they believe an infection is innocuous.

It took me more than 3 months for my biometrics to return to somewhat normal and they are still not really normal. I have also lost more than 3 months of cardio conditioning. Even if I don’t suffer from permanent effects of the virus, I don’t want to go through 3 months of recovery each time. Imagine being infected twice a year (a conservative estimate): I would lose 6 months of health.

This is just the measurable impact on the heart only. We have no idea beyond the elevated heart rate and the lowered hrv, what else was damaged and needs time for recovery. They say each infection could age us ten years:

Under normal circumstances, people lose about 0.2 to 0.3% of their brain matter each year through aging. Yet the study found that COVID patients experienced an additional loss of anywhere between 0.2 to 2% of their brain size in the three years between MRI scans. At worst, that is a loss equivalent to your brain shrinking over 10 years.

Even a mild case of COVID can shrink your brain the same as aging 10 years, study shows

I was semi-joking with my partner that covid increased my resting heart rate by 5-10bpm, so I would just need to get infected 2-3 more times to have a heart of an old person.

moving forward

I am very afraid to get reinfected again, to be honest. I don’t care if this makes me sound like a hypochondriac or a loser. I could visibly feel and see the decline in my physical health, and it took me so much time and effort to be functioning normally again, though I have zero idea what is truly going on within my body. We are still masking indoors, avoiding eating indoors, avoiding social meetups, etc. I do feel really weird existing in a world where everyone else is living as though there is no deadly virus spreading through the air. But looking at my elevated heart rate serves as a good warning and reminder.

We will still try travelling, though I do have some ptsd from Hanoi because that was where I presumably got infected (unless it was from sitting an hour masked around sniffling people in a library). We’re going to try flying with n95s with a sip mask installed, and hopefully this will be enough to keep us safe on the plane. It would be interesting to travel without the experience of eating indoors, but I am curious to see what comes out of the limitations. Apart from the plane itself I think the risk of getting infected is similar to staying here in Singapore. I do wonder if a second infection would truly render me into becoming an actual hermit.