Good morning,

The news never seems to slow down, does it?

Periodically, in my letters to you, I cover health topics I find uniquely relevant to our age group. I’ve covered heart health and metabolism so far this year.

I consume an enormous amount of health-related content, mostly in-depth podcasts from the likes of Peter Attia, Andy Galpin, or Rhonda Patrick. When I decide to write a weekly letter about something, it's always because I think, “I can’t believe everyone doesn’t already know this!”

That is 100% the case this week. I hope you find this valuable.

Here’s what I have for you today:

• One big thing. Lots of things are bad for you. But this one thing is more good for you than any of them are bad. 💓

• You have to check this out. Living two hours in the future. 🕑

• Tools and tech. TikTok robots. 🎥

Are you ready to jump in? 🦘

1️⃣ ONE BIG THING

The Gen X guide to VO2 max: part 1.

When you think about the health factors that will produce a long, vibrant life, what comes to mind?

Avoiding smoking, for sure. Maintaining a healthy blood pressure. Maybe keeping stress at bay. True enough, these are all important.

But there is a single number that predicts your risk of dying from any cause more powerfully than anything else you can measure.

It is your “VO2 max” number, which is a measure of your “fitness.”

As I wrote about in my letter Climbing North of Neutral, there is something about this remarkable fact—specifically that so few people understand it—that has me obsessed.

Every time you go in for an annual physical, they measure your blood pressure. If it is high, doctors will advise changes in diet, exercise, and, ultimately, medication. The same is true for any number of other health problems… smoking, type 2 diabetes, heart disease, etc. If you have one of these problems, you and your healthcare team will work together to resolve it.

Yet few things compare to the negative health consequences of having a low VO2 max.

As Attia says, a high VO2 max score for your age is “more beneficial for you than any bad thing you can think of is bad for you.”

And it’s not even close.

Tracking real-life health risks.

In a 2018 study, researchers followed 122,000 people (with an average age of 53, which is my exact age) for 25 years. During this time, 13,600 of the study participants died. The researchers examined why they died. What did they find?

Study participants with the lowest fitness levels (the bottom 20%) had a 404% higher risk of death from any cause compared to the extremely fit (the top 2.5%). This risk was greater than that associated with traditional factors like end-stage kidney disease (178% increased risk), smoking (41% increased risk), diabetes (a 40% increased risk), coronary artery disease (a 29% increased risk), or high blood pressure (21% increased risk).

What if a study like this could include 750,000 participants?

A 2022 study of veterans did just that. It found study participants with the lowest fitness levels (the bottom 20%) faced a 309% higher risk of death from any cause compared to the extremely fit (the top 2.5%). This risk was greater than that associated with traditional factors like chronic kidney disease (49% increased risk), smoking (40% increased risk), diabetes (34% increased risk), atrial fibrillation (34% increased risk), cancer (33% increased risk), cardiovascular disease (28% increased risk), or high blood pressure (14% increased risk).

I can't imagine more robust and compelling scientific data.

VO2 max is the biggest predictor of how long you will live.

How is this not bigger news?

What the heck is VO2 max?

Here we have this remarkable health biomarker, and if I were to roll the dice a bit, I would guess you are not entirely sure what exactly VO2 max is.

That was me a couple of years ago. I’d heard the term. My best guess is it was a measure of lung capacity.

Let's fix this.

I have given considerable thought to how best to explain this idea. Ultimately, my top priority is to keep this as simple as possible. Let's see how it goes…

VO2 max is the:

• Maximum amount of oxygen your body can use (this is the VO2 part, volume of oxygen).

• When you’re pushing yourself to your absolute limit during exercise (this is the max part).

Think of it as a cumulative measure of your entire oxygen system's efficiency.

Now, since this is all about oxygen, it is natural to think about your lungs.

But oddly enough, your lungs are not the limiting factor in your body’s overall oxygen processing system. In short, your lungs are over-engineered. They can absorb far more oxygen than you can use (when healthy).

Instead, the two factors determining your VO2 max are your heart and your muscles. To better explain, think about your heart as a pump and the muscles throughout your body as big sponges.

• The "Heart Pump" (your delivery system): Your heart is your body's fuel pump, constantly pushing oxygen-rich blood through your body. Your VO2 max is directly limited by how hard and fast your heart can pump that blood through your body. This isn't just one big squeeze. It’s about (1) how much blood your heart can pump with each beat (like a powerful pump stroke) and (2) how many times it can pump per minute (its pumping speed). With training, this pump gets stronger and more efficient, pushing out more oxygen-rich blood with each beat.

• The "Muscle Sponges" (your usage system): Your muscles are like thirsty sponges, eagerly waiting to soak up that oxygen from the blood. Your VO2 max also depends on how efficiently your muscles can take in and utilize oxygen. This has two components:

  • Lots of tiny "pipes" (called capillaries) delivering oxygen right into your muscles. Consistent exercise builds more of these tiny pipes, allowing more oxygen to reach your muscle cells.

  • Super-efficient "mini-factories" inside your muscle cells (called mitochondria) that actually use that oxygen to create energy. Regular training makes these factories larger, more numerous, and more efficient at using oxygen for fuel.

In a nutshell…

Your VO2 max measures the overall efficiency of your heart's oxygen delivery and your muscles' oxygen usage when you're working as hard as you possibly can. It's a dynamic number that can improve significantly with training.

Did that make sense?

Here’s what I’d like to do next to build on this framework:

• Describe how to measure your current VO2 max (below).

• Give you points of reference to understand your number in context (below).

• Discuss ways to improve your VO2 max over time (Part 2, next week).

How to measure your VO2 max.

A VO2 max test is typically performed in a specialized lab or fitness center. They put a mask on your face as you run on a treadmill or pedal on a stationary bike. The mask measures the oxygen you inhale and the CO2 you exhale to calculate how much oxygen you can process.

You can often find testing services at local universities, sports medicine clinics, or national chains like DexaFit. I’d google “VO2 max testing near me”. Expect to pay $75-200 for the test.

One thing to ask about is the protocol the location uses for the test, specifically how long you will warm up before the official test begins. Failure to have an adequate warm-up period will produce a flawed result.

Benchmarking your VO2 max number.

Once you have your number, where do you stand?

The best table showing reference ranges for VO2 max by age group can be found here. Scroll down a bit to the VO2Max/METS Categories table. You will see VO2 max measures for each quartile (low = bottom 25% of the population… up to Elite, which is the top 2.5% of the population).

I have provided this data in outline form for ages 40-49 and 50-59 at the bottom of this newsletter.

I believe your eventual goal should be to measure in the “high” category for your age group.

Dr. Attia is more aggressive, suggesting people aim for an "elite" VO2 max measure of people a generation or two younger than them.

Next week: Part 2.

Stay tuned for Part 2 of this topic next week when we’ll dive into exactly how you can train to improve your VO2 max, why starting now in midlife is crucial, and how this "health retirement plan" will pay massive dividends for your vibrant second act.

VO2 max peaks in your 20s and 30s and then declines about 10% per decade after that. What else is new, right?

But training makes a massive difference. Active individuals typically experience a decline in VO2 max of only 5% per decade. One study found that masters athletes in their 60s had VO2 max levels similar to those of sedentary 30-year-olds.

If you'd like to learn a bit more today, here is a six-minute video of Dr. Attia talking about why VO2 max is the most significant predictor of lifespan.

Find a moment of peace and reflection today, if you can.

See you next Sunday,

Kevin

VO2 Max Reference Ranges for Gen X

Women (VO2 Max ml/kg/min)

• Ages 40-49:

  • Low (<25th percentile): <26

  • Below Average (25-49th percentile): 26-31

  • Above Average (50-74th percentile): 32-36

  • High (75-97.6th percentile): 37-46

  • Elite (>97.7th percentile): >=47

• Ages 50-59:

  • Low (<25th percentile): <25

  • Below Average (25-49th percentile): 25-28

  • Above Average (50-74th percentile): 29-35

  • High (75-97.6th percentile): 36-45

  • Elite (>97.7th percentile): >=46

Men (VO2 Max ml/kg/min)

• Ages 40-49:

  • Low (<25th percentile): <34

  • Below Average (25-49th percentile): 34-38

  • Above Average (50-74th percentile): 39-43

  • High (75-97.6th percentile): 44-51

  • Elite (>97.7th percentile): >=52

• Ages 50-59:

  • Low (<25th percentile): <29

  • Below Average (25-49th percentile): 29-35

  • Above Average (50-74th percentile): 36-40

  • High (75-97.6th percentile): 41-49

  • Elite (>97.7th percentile): >=50