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The New Science of Outdoor Exercise

The New Science of Outdoor Exercise
One of my favorite trails in Las Vegas.

Research suggests outdoor exercise is better for your body, brain, and mental health than gym exercise. Here’s how to use it.


  • Speaking of outdoor exercise and learning how it improves our lives: I’m running a Misogi event in Costa Rica from January 22nd to 26th.

  • It will be a deep dive into how we can use the deep lessons of Misogi to live better. We’ll cover mindset, exercise, nutrition, stress management, and more. We will, of course, do a Misogi.

    Get a signed copy here. Then claim free bonuses here.

Today, we’re covering why you should exercise outdoors this fall and as long into winter as possible. Specifically, why you should spend more time on rough ground. The science on this topic is deep, growing, and fascinating.

It’s showing that exercise in nature has many slight edges over indoor exercise that make it powerful for improving our fitness, healthspan, and lifespan.

The New Science of Outdoor Exercise

In short

Our ancestors evolved to do high levels of physically and mentally demanding activity outdoors. That still matters today.

The details

While reporting The Comfort Crisis, I spoke with David Raichlen. He’s an anthropologist at the University of Southern California.

He has a traditional lab at the University. But most of his work occurs in the field, in far-off places, working with some of the last remaining hunter-gatherers.

Raichlen asks big questions about exercise. Like: How did exercise shape early human beings, and how can that guide us today?

He told me that humans split off from chimps and began hunting and gathering somewhere between 13 and 4 million years ago (I realize that’s a somewhat ludicrous range, but cooking up a species that takes over the world and invents amazing technology like spaceships, iPhones, and Pop-Tarts takes time).

Our role as hunter-gatherers changed and shaped us. Our chimp predecessors were relatively lazy. Humans, on the other hand, had to be extremely active to survive.

Our bodies adapted to this higher level of physical activity to maintain the health of all of our organ systems. Not just our heart and lungs and muscles—everything. Especially our brains.

“Hunting and gathering are not only physical acts, but also cognitive acts,” Raichlen told me. As people hunt and gather, they’re not just covering ground and carrying stuff. They’re also running all sorts of calculations in their head. For example:

  • Figuring out how they should pace themself in the heat.
  • Determining when to dial up and back their effort during a pursuit.
  • Noticing details in the environment like disturbed ground or a bent branch to track the animal.
  • Reading and even smelling the land to determine where food is.
  • Building a mental map of where they are in a vast landscape.

And this mental work still matters today. “When you combine physical acts with cognitive acts, it tends to have a really beneficial effect on the brain,” said Raichlen. It’s likely one reason that people who exercise outside more tend to age far better.

“For example, older Hadza still contribute food and resources; they age very successfully,” he said. “They often have the same level of physical activity in their 70s as they did (in their 30s).”

The average Hadza walks 5.5 to 10 miles over rough ground as they hunt and gather. They don’t seem to get age-related brain and physical diseases like dementia and heart disease.

The (Sort Of) Problem with Indoor Exercise

In short

Indoor exercise lacks many of the extra benefits we can get from exercising outdoors.

The details

To understand why outdoor exercise often trumps indoor exercise, we have to consider what exercise indoors is like.

Think about running, rucking, or walking on a treadmill.

We stand on the belt and set the television to our favorite show. Then we punch in the exact speed and incline we want. Then we can zone out because the exercise is the exact same from the first second to the last.

And this happens in a setting where all the variables are controlled. It’s predictable, temperature-controlled, and comfortable.

This exercise is convenient, and it works our cardiovascular system. And that’s fantastic.

But the missing link goes back to the work we must do between our ears …

Your Brain on Outdoor Exercise

In short

Exercising outdoors is far more mentally demanding, which may improve brain health as we age.

The details

Few of us are tracking animals or looking for a good place to dig up food as we work out.

But think of it like this: If running on a treadmill is like addition and subtraction, the way humans evolved to exercise is more like multivariable calculus.

Still today, outdoor exercise is still closer to multivariable calculus than it is addition.

I’ll use my experience running the Mojave Desert trails near my home as an example.

As I run, the rocky ground forces me to play something like moving Tetris. With each step, I must quickly angle and land my feet in slits of flat ground between serrated rocks, pivot on loose dirt, sidestep spiny cacti, or hurtle tiny cliffs.

If I zone out, I’ll be hobbling home on a twisted ankle or eating schist.

To get a sense of foot Tetris, here’s a clip of one of the trails I frequently run:

Each step is a new encounter and nothing is pre-programmed. The trails can be like a roller coaster, with ups and downs and long and winding ascents and descents. I have to quickly consider many variables:

  • How should I pace myself?
  • Should I hammer up this hill, or will that lead me to bonk later on?
  • If I bomb down this downhill section, how should I position my body in space and pace myself relative to the slope of this hill, given that it’s covered in loose dirt?
  • Are those rocks I need to run up sharp enough to cut into my shoes, and should I go around them?
  • How should I angle my foot as I run through a patch of rocks?
  • Are there agave or cactus hanging onto the trail that could cut me? (I come home bloody half the time, FWIW).

And how about exposure to the elements? Until late September, the Mojave is hot in the sense that the surface of the sun is hot.

I have to leave home early (hunter-gatherers time their gathering to sun exposure). I also have to calculate water usage and alter my pace based on how much sun exposure I’m getting. Hell, I have to change which trail I’m on based on the sun’s location.

So, yes, it’s much more cognitively demanding than indoor exercise.

But also more physically demanding …

Your Body on Outdoor Exercise

In short

Covering rough ground burns 28 percent more calories compared to roads, according to one study.

The details

On the first truly hot day this spring, I had a moment of feeling totally spent.

I’d decided to run a desert trail I hadn’t in a year. I forgot just how gnarly this trail was. It’s eight miles. That’s a distance I regularly run on the trails.

But this eight miles includes far more up and down and runs atop a jagged ancient sea bed.

The amount of effort packed into that eight miles felt like 20 on a treadmill. Science suggests my notion isn’t entirely wrong.

The rough, unpredictable ground also challenges our bodies more.

Biomechanists at the University of Michigan discovered that the increased challenge of walking or running on rough, uneven ground leads people to burn 28 percent more energy per step. That bears repeating: 28.

Of course, that figure is a generality. A tame and flat trail would likely out-edge a treadmill by, say, 10 percent (that figure is based on some old data comparing walking on treadmills to walking outdoors).

But a rough, up-and-down trail like the one I was on might push us to burn perhaps 50 percent more calories per step.

And it requires more strength, thanks to steeper climbs and descents and more obstacles.

In short: The figure suggests that we’ll do much more physical work per distance on a trail, the number dependent on how gnarly the trail is.

Your Attitude on Outdoor Exercise

In short

Research shows that outdoor exercise is better for mental health.

The details

After that aforementioned butt-kicking desert run, I felt good. Tired but good. Like I’d accomplished something real and hard. I was riding high the rest of the day.

Scientists in the UK recently analyzed 26 studies on how exercise in nature compares to exercise in a city or indoors. Their takeaway:

“Physical activity undertaken outdoors in natural environments is more beneficial for a range of psychological outcomes compared with urban environments.”

They discovered that exercise in nature led to greater increases in happiness and energy, and bigger decreases in anxiety, fatigue, and feelings of “hostility.”

Hostility is the most hilariously strange scientific measurement ever, but yeah … I guess I did feel less hostile after my hard outdoor run.

How to Use It

I realize it’s hard for some people to access nature. If that’s you, and you feel chained to the treadmill or can only ruck in a bustling city, that’s fine!

Again: All exercise is great. This topic isn’t a “bad, good, best” thing. It’s more like this:

  • Great: Any exercise at all, indoors or outdoors.
  • Greater: Exercise outdoors
  • Greatest: Exercise in wild nature, on a trail

For example, those researchers in the UK found that exercising in a city park also gave people more benefits than an indoor gym. Even just 15 minutes helped.

So if you have any opportunity at all to do more exercise in nature, you should absolutely take it. I do one trail run every Sunday and wear a ruck when I take my dogs out into the desert.

Have fun, don’t die, and, as my friends from Huckberry say, see you out there …


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