🩺📊 What's all the data for?

All Day Solution without an All Day Problem

I own an Apple Watch. And I’ve owned one for a long time.

I purchased the first version of it years ago. Back then the thing existed to tell time and relay notifications to you. When I sat down at my desk while wearing it, I felt like I was in a stress test exercise. My laptop, my phone, and my watch all buzzed at the same time to alert me to every new Slack message. I returned it the next day.

Over time, the Apple Watch evolved into a health device. They also added more nuanced controls to it to avoid the deluge of notifications. And some apps became actually useful (Streaks, Strong). I am someone who enjoys being active and the workout features became hard to beat. So I picked one up again in 2019 and relied on it as my primary timekeeping device for the last five years.

And I generally like it. Die-hard Garmin heads will debate this, but I think the Apple Watch is the greatest outdoor running device ever made. And using the Strong app for lifting with the gym is both delightful and the best way to avoid being the guy who sits on his phone taking up the bench.

I just have two issues with the device:

I also like wearing “real” watches.
I feel compelled to either wear it at-all-times or not-at-all because, at first glance, that seems to be the only way to get an accurate picture of my health.

So I’m going to ask two simple questions and see what I find:

How valuable is it to wear some kind of fitness tracker?
And, if valuable, how much do you need to wear it?

Both of these are asked in the context of the popularity in my circles of Huberman/Blueprint etc. When I talk to friends and family who are actual doctors, they all say “y’all are all nuts. Just follow a few simple rules.” But tech bros want to optimize. Let me have this.

Important Notes

I am lucky in the long-term and disciplined in the medium-term.
When I consider my health, I am generally fortunate so far. The biggest health scare I’ve had was a collapsed lung as a teenager that required surgery. And, sure, my knees aren’t great and I’m prone to joint swelling from palindromic arthritis. Annoying and painful, but not yet life threatening or debilitating.

I’m lucky. I do not suffer from the kinds of chronic conditions that would impact my life expectancy or significant quality. That can change any moment, of course, but for now I do not have special medical needs that would require me to focus on any particular condition or testing.

And in the medium-term I am religious about my health habits. I exercise daily. I eat well. I wear mineral-based sunscreen. I avoid booze most days. I sleep as much as a new parent can. I do all the things my doctor friends say meet the “good enough, stop worrying” definition.

I don’t miss a day.
I don’t need a fitness tracker in the motivation sense. I follow a pretty regimented fitness routine. I run three times a week, typically for four miles. I lift weights three times a week. And I live in a dense European city where I walk a lot.

All to say - the impact these fitness trackers provide in getting people up and moving is a non-factor in my case. The value that seems to offer to others is wonderful and I’m encouraged by it and love it when I talk to people who have been able to change habits based on these kinds of things. I just don’t need it for that purpose.

So what data matters?

When we obsess over health data (again, to the annoyance of real physicians), what actually matters? I am thinking about this in terms of health data that indicates long-term trends. If you are in the hospital with pneumonia, then your blood oxygen levels really do matter at this moment. If you are healthy at home, they probably don’t.

These wearable devices want you to believe that all of the data they capture matters. Which makes sense as a marketing campaign. I am skeptical. I am also not a scientist so this is pretty anecdotal.

So what data do I care about in my current state and how do I approach it?

Blood and Urine Laboratory Tests

I do this annually. Combined with the cardiovascular test below, this is as good as it gets in terms of measuring my health.

If I had something that was worrying me, I suppose I could do this twice per year.

Cardiovascular Laboratory Tests

I also get my heart checked up annually with a full stress test at the clinic. Family history of high blood pressure. This gives me a solid baseline.

Skin Cancer Screening

I’m even whiter than I look. I get screened annually at Hospital da Luz. I am pretty sure that my Portuguese doctor tells his friends after each time I visit that he saw a ghost.

Exotic or Specific

I’m going to ignore some of the more exotic testing out there like full-body MRIs. This is one place where I’m going to just defer to my doctor friends who say that it’s generally insane and causes more stress than the value it creates.

Home Measurements

That leaves me with what I can measure at home, which should help frame the answers to the questions up top.

As part of that pivot into health, the Apple Watch throws off a lot of data. And I don’t find most of it useful. I’m going to rule out most datapoints to start. My walking asymmetry, for example, is potentially curious but not a real indicator of health for someone in my general condition. A lot of the metrics captured are like this. For a young (ish), healthy individual the trends might be interesting but are not actionable.

Again, these might be very useful to other people. I can imagine someone in their 70s caring about walking asymmetry. Or someone recovering from an injury to their leg etc.

So, to narrow this down, I’m going to consult the service I use before I text any of the physicians I know - Artificial Intelligence. I posed a question to ChatGPT 4o around what metrics are indicative of health. You can see the response here. Combined with some of my own reviews, I have narrowed down a few data points that interest me.

First, some keys. This first table represents what I have available to me at home or what I could go out and purchase on the consumer market.

Symbol	Device Used to Measure
🩺	Withings Blood Pressure Monitor
⌚	Apple Watch or Whoop
🛏️	Eight Sleep Mattress or Oura Ring
⚖️	Withings Body Comp Scale
⛔	Cannot Measure at Home

Next, this table represents the very rough estimation of value of these metrics.

Symbol	Value as a Measure
⭐	1-5 Star Rating
*️⃣	Maybe Useful When Sick
🤔	Skeptical About Value
0️⃣	Just No Value

Health Indicators

These are the data points that appear indicative of overall health. Ranked by the value they provide. The goal here is to determine if I can measure them at home and, if so, what I need to do to capture that data.

Data Point	Value	Test Environment	Home?
Blood / Urine Analysis	⭐⭐⭐⭐⭐	Laboratory	⛔
Cardiovascular Stress Test	⭐⭐⭐⭐⭐	Clinic	⛔
Skin Cancer Screening	⭐⭐⭐⭐⭐	Clinic	⛔
Resting Heart Rate	⭐⭐⭐⭐	Sleep	⌚🛏️
Blood Pressure	⭐⭐⭐⭐	Upon Waking	🩺
Heart Rate Variability	⭐⭐⭐	Sleep	⌚🛏️
VO2 Max	⭐⭐⭐	Exercise	⌚
Body Composition & Weight	⭐⭐⭐	Upon Waking	⚖️

Health Best Practices

These are data points that are more “best practice” routines. They could manifest in indicators down the road, but are more of a circumstantial or habitual measure.

Data Point	Value	Test Environment	Home?
Sleep Stages	⭐⭐	Sleep	⌚🛏️
Respiratory Rate	*️⃣	Sleep	⌚🛏️
SpO2	*️⃣	Sleep	⌚🛏️
Recovery	*️⃣	Sleep	⌚🛏️
Strain / Activity / Caloric Burn	🤔	Always On (mostly)	⌚
Daytime Heart Rate	🤔	Always On (mostly)	⌚
Stand Hours	0️⃣	Always On	⌚

Sleep only warrants two stars here because the data is not terribly useful. The answer is always the same. Keep a consistent sleep routine, be active during the day, leave your phone out of the bedroom, avoid booze, and try to manage stress.

So what?

Alright, so the highest value metrics are not available at home. The four and three star metrics require either using a device during sleep or once upon waking (with the exception of VO2 max, which should be measured during strenuous exercise). Either way, not in a constant-wear environment.

The next tier of metrics either offer conditional or questionable value. Respiratory rate and SpO2 are really only useful if you are trying to measure an imminent or ongoing illness - similar to body temperature. And, again, those are best measured during sleep.

The questionable values are things like stand hours and caloric output. At least in my case. Like I mentioned above, I am extremely disciplined about my level of activity. In theory I could tailor my workouts to my strain or recovery metrics, which from what I understand is the real value of Whoop, but maybe I’m old school because I can generally tell things like “hm, I slept bad and ran too fast yesterday. I’m beat. I’m going to take it easy with the weights today.”

So what are the answers?

How valuable is it to wear some kind of fitness tracker?

For someone who is generally healthy and maintains a strict exercise routine, with or without a tracker, the value seems to be in measuring data during strenuous exercise.
- The metrics captured outside of exercise during the day are questionable.
Sleep data can be useful but requires either being fine with wearing something while you sleep or investing in something like an Eight Sleep mattress (which I do own).

And, if valuable, how much do you need to wear it?

During strenuous exercise only (assuming you have some kind of sleep solution if that data is appealing to you).
All-day wear is really only useful if:
- You’re worried about catching a surprise arrhythmia and want an alert about it or you’re in something like a car crash where you need the emergency response features.

The real value seems to be consistency and your day-to-day habits. The actions this data would drive you to take are pretty universal. Maybe the doctors are right…

What about phone independence? Or watch-as-tool?

Wrist watchers were meant to be tools. The Rolex Submariner was a state-of-the-art diving watch that kept you safe. And now it is often just a tool worn by tools to signal status.

I like to think about the Apple Watch along those original “tool” watch lines. This thing is really useful. And in many cases, especially on the weekend when I am hanging out with my kid, it strikes the perfect balance to prevent me from pulling out my phone while making me available if another family member needs something. Bonus that the thing is easily cleaned. When you have a toddler, everything on your person gets sticky.

The goal of this exercise isn’t to eliminate an Apple Watch once and for all. The goal is just to answer the question of how often you need to wear it if the health metrics are valuable to you. And I feel like I’ve answered that. The Apple will live on the wrist when it makes sense because I want some of its functionality, not because I want the measurements of things during the day.

So what is my plan?

I do care about the sleep data. I also hate wearing something like a watch or band when I sleep. So I’m going to try the Oura ring out.
The daily point-in-time morning measurements (scale, blood pressure) are no-brainers.
I do not care so much about daily strain, daytime stress, or stand minutes. I’m not going to worry about wearing something during the day.
- The exception here is when I want to wear it for one of two other purposes:
  - When I am working out (running/lifting with an Apple Watch is just perfect).
  - When I’m relying on it as a useful tool.