Eleven Kilometers in Sambas

Hey {{first name | reader}},

It's Tuesday, which means your weekly fitness check-in. Welcome to Week #33.

An eleven-kilometer hike in the Amazon with a ten-year-old is a different animal from an eleven-kilometer hike in the Bay Area with a group of seasoned hikers. Credit to my niece Margot, who waited until we had finished to complain about it, and who was rewarded, as we all were, with a swim in the clear water of the Tapajós.

She walked the entire thing in Adidas Sambas.

My feet have not been able to do that since 2020.

"Plantar fasciitis" was a punchline to me until one morning during the 2020 lockdown, when I woke up with a searing burn across the bottom of both feet and nearly crawled across my very small apartment. Training for a 10K in the morning and then walking ten miles a day in worn-out shoes turns out to be a great deal of load for one band of connective tissue.¹

Since then, my feet get attention.

Calf raises and tibialis raises go into leg day — the calves point the foot down, the tibialis pulls it up, and most people train exactly one of those. When my Achilles starts editorializing, I add calf stretches. I should stretch my feet more than I do. I am telling you this, not modeling it.

I have run long enough to have lived through every shoe fad. Heavy supportive shoes to correct pronation. Barefoot shoes, which were going to make our feet strong again. High-drop shoes for Achilles problems in one decade, low-drop shoes for Achilles problems in another. Somewhere in there I learned that ballet flats are not walking shoes past about a mile, and since the pandemic my stilettos have mostly been in the closet, performing decorative duties.²

The strange thing is that the fads weren't entirely random. Each one grew out of a theory about why runners get hurt: pronation is the problem. Impact is the problem. Shoes are interfering with the way your body naturally wants to move. Or, eventually: maybe just wear the shoe that feels good.

A 2022 review walked through four major paradigms that have influenced running-shoe design and found limited evidence supporting any of them as a reliable way to prevent injury. Which explains the whiplash. The recommendations kept changing because the theories underneath them were never as settled as the shoe wall made them look.

The most useful conclusion is also the least exciting: shoes should be reasonably light, comfortable, and not burdened with more corrective technology than you actually need.

Fifty years of shoe philosophy, and your feet still get a vote.

So I run a rotation, not because any study told me to, but because different jobs feel different. Two pairs of trail runners for urban hikes. Hiking boots and a low-cut hiking shoe for the serious ones. Running shoes for daily walking. Low-drop shoes for leg day. I swap the factory insoles for inserts with a bit more support.

The day before the France trip I panic-bought trail runners from a brand I had never worn, which was a reckless thing to do before two weeks at 20,000 steps a day.³[3] They have since carried me through France, Brazilian cities, and the rain forest without one complaint.

But none of those shoes fixed my feet.

The thing that finally broke the cycle was a pair of ugly rubber flip-flops with little nubs all over the footbed. A friend suggested them after rest and stretching had gotten me nowhere. I bought them out of desperation. Within a week, the pain was gone.

I still wear them around the house.

I don't know that the flip-flops cured anything. I do know that they made walking tolerable long enough for me to start loading the tissue again. And the calf raises are what seem to keep the problem from coming back.

That is a much smaller promise than the shoe industry usually makes.

The shoes don't need to fix you. They just need to stop making things worse.

Question: How do I know when it's time to replace my shoes?

Answer: Sooner than you'd like, and probably not by a mileage number.

The familiar 300-to-500-mile rule is more rule of thumb than biological law. Midsole foam changes as you use it, but how quickly depends on the material, your body weight, how you move, what surface you're on, and whether you're rotating shoes.

The number on the box is not measuring your shoes.

Better signals: the shoe suddenly feels dead underfoot, the outsole is visibly worn down, the shoe is leaning or collapsing to one side, or an old ache starts showing up again.

For me it's the left arch, and it reliably appears about two weeks after I should have noticed.

Write the purchase date inside the tongue in permanent marker. Then you have information instead of an argument with yourself in the closet.

Myth: Plantar fasciitis has a straightforward treatment: rest, stretch, strengthen, repeat.

Reality: The evidence is considerably messier than that.

Rest did nothing for mine. Stretching gave me temporary relief (think minutes). And although strengthening exercises — particularly heavy, slow calf raises — have evidence behind them, that isn't how mine got better. I wasn't doing a loading program at all.

Mine disappeared after I started wearing the aggressively nubbed Adidas flip-flops described in footnote 1. I have no randomized controlled trial for this. I have two feet.

There are plausible reasons why pressure or massage to the bottom of the foot might reduce symptoms, but I can't tell you that the flip-flops "treated" my plantar fascia, much less how. I can tell you that after months of pain, I wore them and within a week the pain was gone.

The useful lesson is not buy these flip-flops. It's that plantar fasciitis is one of those injuries where the evidence supports several approaches, individual responses vary, and the thing that works for you may not be the thing that was supposed to work.

Santarém sits where the Tapajós meets the Amazon, which means the protein situation is excellent and the texture situation is better than I had any right to expect.

This week's Fuel Box is a plate, not a recipe.

Grilled river fish — tucunaré or pirarucu, whatever came in — cooked over charcoal, skin crisp, served whole and unapologetic.

Alongside it, farofa: toasted cassava flour, usually cooked with butter and onion, sometimes with bits of bacon. It is essentially a crunch delivery system. It goes on everything.⁴

Both of these are new additions to my regular rotation, which almost never happens at this point.

Add grilled vegetables and this is the meal I've eaten most often in the north, and the one I'll be attempting to reproduce badly in my own kitchen by September.

Agresta et al., "Running Injury Paradigms and Their Influence on Footwear Design Features and Runner Assessment Methods" (Frontiers in Sports and Active Living, 2022). Open access, free, no login.

It's a journal article, so skim the biomechanics and read the four paradigm sections. They lay out the major theories that have driven running-shoe design over the past half-century — pronation control, impact force, habitual motion path, and comfort — and then show how much shakier the evidence is than the certainty of the marketing.

If you've ever wondered why the shoe advice you got in 2004 was almost the opposite of the advice you got in 2014, here's your answer. With citations.

They also mention the Onitsuka Tiger in the history of cushioned running shoes, which explains a great deal about my closet.

The single-leg calf raise, as a test before it's an exercise.

Stand on one foot near a wall, fingertips on the wall for balance only — no leaning. Rise all the way onto the ball of your foot, pause, then lower all the way down slowly.

Count until your form breaks or your heel stops getting all the way up.

Then switch sides.

A healthy adult can often manage somewhere around twenty or more, although age and testing method make the exact number less interesting than the comparison between sides.

If you're well under that, or one side is clearly behind the other, you've found something worth knowing.

Then do three slow sets on each side, twice this week, and stop treating your calves as scenery.

Mine came out lopsided.

It's the left.

I can't say I was surprised.

Stay strong,
{{first name | reader}}

P.S. Margot walked eleven kilometers in Sambas and felt nothing at all. The nubbed flip-flops will be waiting for her in about thirty years.