This issue took thirty-eight drafts.
An article about why showing up imperfectly beats waiting to show up perfectly.
The irony was not lost on me.
The trail doesn’t grade your preparation.
It just asks if you showed up.
That applies here too.
The Number
There is a number that ranks among the strongest predictors of your health, longevity, and physical performance.
Most people see the number on a watch or app and move on. Few understand what it actually represents.
It’s called VO₂ max. If you’ve seen the number, you probably thought of it as a fitness metric. The research suggests it’s something more important than that.
Feeling fit and being fit are different things. VO₂ max is the difference.
Every article about improving it sends you to a track or a treadmill. But if you’ve been showing up on the trail week after week, you’ve been training it already.
VO₂ max doesn’t respond to motivation, plans that stay on paper, or the days you meant to show up.
It responds to repetition over time. But not just any repetition.
Showing up matters. Showing up at an effort that challenges you matters more.
Push past your comfort zone consistently and the number improves. Stay in your comfort zone and it doesn’t. The difference is intensity. Not every session. Not heroic effort. Just enough challenge, often enough, over enough time.
Every time you lace up and hit the trail, something happens that you can’t see in the moment.
A small adaptation. A marginal improvement. A deposit into your health account, one that compounds.
Most people never open that account.
You’ve been funding it every week.
What Is VO₂ Max
The limiting factor on long climbs is oxygen. VO₂ max is the maximum rate at which your body can use oxygen during sustained effort.
Think of it as engine size: the bigger the engine, the more work your body can do before fatigue sets in.
And it turns out engine size predicts more than performance. It is now considered one of the strongest independent predictors of longevity in the medical literature.
A 2018 study analyzing 122,000 adults undergoing treadmill testing found that higher levels of cardiorespiratory fitness were strongly associated with lower long-term mortality risk.
The implication is difficult to ignore.
The American Heart Association notes that cardiorespiratory fitness may predict mortality more strongly than traditional risk factors such as hypertension, high cholesterol, smoking, and type 2 diabetes.
In a separate large treadmill study, fitness-associated biological age varied by as much as three decades within the same age group.
Researchers studying aging increasingly frame it as something else: reserve capacity.
The higher your aerobic capacity, the more room you have before ordinary life begins to feel like effort. Climbing stairs. Carrying groceries. Walking uphill.
Training today is not just about performance. It is about pushing that threshold decades into the future.
Long, sustained efforts on the trail quietly build that reserve.
It is not a fitness vanity metric.
It is a health metric.
And it is trainable at any age.
Why Hiking Moves It
Most people assume improving VO₂ max requires running, cycling, or structured intervals.
It doesn’t.
What it requires is sustained effort at an intensity that meaningfully elevates your heart rate, often well above comfortable levels, held long enough to force cardiovascular adaptation.
Our hikes hit it consistently: sustained elevation gain, uneven terrain, heat exposure, and a pace that doesn’t allow full recovery between climbs.
Eight to ten miles with 1,500–2,500 feet of gain at a pace that keeps your heart rate elevated for two to three hours.
That isn’t a casual hike.
That’s a VO₂ stimulus.
Long climbs force sustained effort. Your heart rate rises, breathing deepens, and the cardiovascular system has to adapt.
Which means the part of the hike many people dread is often doing the most work for you.
Sometimes it even has a name.
Dreaded Hill.
You can watch it happen. There is always a point on a long climb when the conversation fades and everyone settles into their breathing. The group spreads out, the hill takes over, and the work becomes quiet. That moment is where the aerobic engine begins to matter.
A treadmill can reproduce heart rate and pace. It cannot reproduce terrain, uneven footing, sustained elevation, or the accumulating fatigue of long climbs.
What happens on the trail is harder to quantify and harder to fake.
There is one more variable a treadmill cannot replicate: the people next to you.
When the standard around you is to keep moving, you keep moving, longer and harder than you would alone.
The group pace isn’t incidental to the training effect.
It’s part of the stimulus.
You already know this. You’ve felt it.
The Compounding Effect
VO₂ max doesn’t reward impatience. The gains are slow, cumulative, and often invisible in the short term.
You cannot feel it improving week to week. There is no single hike where you notice the adaptation happening. The deposits are too small and the timeline too long.
Compound interest never announces itself. It accumulates quietly.
Then one day the climb that used to break you doesn’t. The pace that used to feel like a ceiling becomes your floor. Recovery that used to take days takes hours.
That is not motivation. That is not a good week.
That is months of consistent effort paying out.
The evidence points in one direction. VO₂ max responds to repeated stimulus over time, not isolated hard efforts.
Showing up imperfectly, repeatedly, compounds faster than showing up perfectly, occasionally.
Most people overestimate what one hard week can do and underestimate what a consistent year can do.
They wait for the perfect training block. The right schedule. The right conditions.
Meanwhile the people who simply keep showing up are quietly building something they can’t lose in a week.
The Practical Takeaway
You don’t need a gym.
You don’t need a complicated training plan.
You don’t need to understand the physiology.
You just need three things.
Intensity.
A pace that elevates your heart rate and makes conversation difficult on the climbs.
Duration.
Two to three hours of sustained effort builds the aerobic base that VO₂ max depends on. The trail gives you this naturally.
Consistency.
Every week you show up is a deposit. Every week you don’t is a missed one.
The account doesn’t close. But the compounding slows.
Every time you show up, you are adding to your aerobic reserve.
The trail is the program.
Showing up is the method.
Time is the ingredient most people aren’t willing to invest.
You already are.
Trail Lab Field Notes
Same route.
Same pace.
Heart rate 13 beats higher.
I compared two runs of the Mustard–Billy Goat loop on my Garmin. The only meaningful difference was glycogen availability the day before. When muscle glycogen is low, the cardiovascular system works harder to produce the same output. A controlled study found exactly that.
The engine was running on less fuel and charging more for the same work.
A higher heart rate on a climb can mean two things. Sometimes it reflects effort, the stimulus that builds aerobic capacity. Other times it reflects fuel limitation, the system straining to sustain output on insufficient glycogen.
The goal isn’t simply to elevate heart rate. It’s to elevate it through work, not because the engine is running on fumes.
What you consume at mile five often determines how mile eight feels.
People ask on the trail what I use. PROBAR BOLT Energy Chews. Light, quick, and easy mid-effort.
On The Trail
Something has shifted in this group over the past year.
The pace has gotten faster. Not by design. By compounding.
The people who have been showing up week after week have quietly raised the baseline. What felt fast a year ago feels normal now. What felt normal a year ago feels easy.
I’ve noticed it in myself. Climbs that used to demand everything now demand less.
Not because they got shorter.
Not because the elevation changed.
Because the engine got bigger.
If you’ve wondered why the pace keeps climbing, now you know.
It’s not ego. It’s not showing off.
It’s what consistent effort looks like after months of compounding.
And if you’ve been showing up consistently, even on the weeks it was hard, even on the weeks you had every reason not to, you’re building the same thing.
You just can’t see it yet.
And if you haven’t been showing up yet, that’s fine.
The compounding starts the moment you do.
Start showing up.
Keep showing up.
What This Newsletter Is
Field notes on human capacity, written from the trail.
Not So Casual Hikes started as a Sunday hiking group in Southern California. Two years later, it's become a training community for people who show up consistently and push each other to do more than they would alone.
If you’re new here, start with the first issue, it’s where this all began.
Twice a month.
Always short.
Always honest.
Always worth five minutes.
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