Estimated read time: 5.12 minutes (about as long as it takes to talk yourself out of an ice bath, it should be 2 seconds cause honestly do they even work 🤔)

Hey Performance Nerds! Jonah here. 🤓

The "recovery run" gets treated like its own training category. The science says that category doesn't exist.

Easy running and recovery are different jobs. Easy running can only do one of them.

I run seven days a week. I think zero of them are "recovery runs".

Here's what you'll learn today:

(Augie naps 7 days a week. Something tells me he’s the one doing life right.)

Earlier this week I sent an email with the subject line "This one's free. The next one won't be."

It's a marketing tactic I got bad advice on, and I don't like it.

I realized I don't love marketing. I love sharing the science with you.

Two things happened after.

A lot of you replied excited about the paid edition. You wanted the deeper translation. That hit.

But other replies stopped me cold. People worried they couldn't afford it. People who didn't want to lose access to the science. That's the part I have to sit with.

Here's the honest version.

I lose money on Marathon Science every week. I've been pushed by advisors to monetize harder. I listened. That subject line was the result.

The truth is I don't care about the money the way I care about the mission. I want to keep doing this because I'm obsessed with translating science for you.

I value your trust. It means everything to me.

So here's what's true going forward.

Science is a right, not a paywall. I'm not going to be the next gate between runners and the research that helps them.

If you want in, you get in. Here's how:

I'm dropping the price. The new pricing is built around access, not a funnel.

Pay whatever you can. The point is access.

Here's my promise.

No more marketing emails. When the membership opens in a few weeks, I'll share the link inside this newsletter. Nowhere else.

The price will never go up. That's a public pledge.

If this costs me money for a long time, it costs me money. I'd rather lose money doing something honest than make money doing something I'd be embarrassed to defend.

Thank you for sticking with me on this. 🫡

Speaking of cutting through the noise, today's piece is about a popular idea most runners get wrong.

Easy runs and recovery runs are not the same job. Let's get into it.

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That ratio is why I've never had a GI issue with it in 3 years of racing. Fast absorption, no gut bombs. I don't earn a commission on this. I negotiated 15% off for you because I believe in the science behind it.

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💡 See this week’s full Stryd training tip at the end of this newsletter.

Easy running has one job: build aerobic fitness through accumulated volume.

Recovery has a different job: offload damaged tissue so it repairs faster than you stack new stress.

One slot in your week can't do both.

The reason elites log so many easy miles isn't recovery “miles”. It's volume.

Boston Marathon data backs this up. DeJong Lempke (2025) tracked athletes across the year before race day. More weekly volume across the year was associated with faster finish times.

Easy run = low intensity volume stimulus, not no stress.

The mismatch comes from runners assigning two jobs to one slot. The slot does the volume job, not the recovery job.

What an easy run doesn't buy is repair of the tendon, bone, and muscle damage from yesterday's session.

Those tissues still take a load even on your “recovery runs”.

The muscle damage doesn't disappear because you slow down. The mechanical load doesn't either.

Edwards (2018) treats running injuries the way engineers treat metal fatigue.

Think about bending a paperclip back and forth. Each bend adds a tiny amount of damage. Eventually it snaps.

Bone, tendon, and cartilage work the same way. Every stride deposits a small dose of damage that stacks across thousands of strides per run.

Keller et al. (1996) measured vertical ground reaction force at roughly 2x bodyweight at slow jog speeds. A 60-minute easy run is still roughly 5,400 strides at 2x bodyweight per step.

Hreljac (2004) put it simply: overuse injuries come from cumulative load exceeding tissue tolerance. The tissues don't care what you labeled the run.

That's how the day-after-hard "recovery run" can push weekly volume past your tissue's tolerance line.

Match the day-after-hard feeling to what your body actually needs.

Most marathon blocks need easy runs and some complete rest days, depending on how much hard volume you stacked.

The decision table tells you what to do today. Here's what the load shape looks like across a balanced week.

Easy days are volume days. Recovery days are recovery days.

Different slots, different jobs based on your goals.

The "but I feel better after a recovery run" feeling is real. The biomarkers don't always agree.

Van Hooren and Peake's narrative review in Sports Medicine pulled together over 100 studies on active cool-down vs passive rest:

The science:

A recovery run feels like recovery. The blood and muscle markers say it isn't always.

"But the pros do recovery runs."
→ Pros log easy doubles because their tissues handle the cumulative load. The label is loose. The function is volume, not recovery.

"I always feel better after a slow shakeout."
→ Perceived recovery is real. Tissue recovery isn't the same thing. Sleep moves the recovery needle more than another slow run.

"What if I just go super slow, like 12-minute pace?"
→ Slower pace cuts per-step load. It doesn't eliminate it. Tendons and bone still take a hit on every stride.

Bottom line: stop thinking “easy runs” speed up your muscle recovery. Every run loads your tissues.

Welcome to the prove you’re a nerd section. Each week, I ask a question about a common running science myth.

Answer correctly, and you’ll be entered into a weekly raffle to win a package of Jonah’s favorite supplements.

A lot of runners assume that if you keep taking gels, you can keep your body running mostly on carbs forever.

Your physiology disagrees 😅

The correct answer?
A. It's hard to fully replenish muscle glycogen during exercise, so as stores run low, your body protects remaining carbs and shifts more toward fat oxidation 🪫➡️🥑 ✅

Even with aggressive fueling, your muscles usually burn carbs faster than you can replace them during long races. As glycogen levels gradually fall, your body shifts more toward fat to conserve what’s left, especially deep into ultras or long marathon efforts.

Here’s how the votes shook out:
🟩 A. It's hard to fully replenish muscle glycogen during exercise, so as stores run low, your body protects remaining carbs and shifts more toward fat oxidation 🪫➡️🥑 – 219 ✅
⬜️ B. Carb intake tops out around ~90g/hr, so you eventually “run out” of incoming fuel regardless of pace 🚧🍯 – 30
⬜️ C. Your pace naturally slows over time, and lower intensity always means fat becomes the dominant fuel 🐢🔥 – 11
⬜️ D. Fat becomes more efficient than carbs late in races due to mitochondrial upregulation mid-run 🧬⚙️ – 20

A few of you went with the “90g/hr ceiling” answer.

There’s some truth there. Gut absorption does cap how many carbs you can take in per hour. But the bigger issue is that working muscle can still burn through glycogen faster than incoming fuel can fully replace it, especially at moderate-to-high intensities.

Bottom line?
Fueling helps delay the wall. But in long ultra races, your body is still playing glycogen defense whether you realize it or not.

I ran an easy 6 on March 16, the day after a hard long run. Heart rate stayed low. Pace, time-in-zones, and TSS all called this a textbook recovery day.

Then I checked my LBSS (Stryd's Lower Body Stress Score). The run had still posted real mechanical load, even if it was less.

This is one reason I love Stryd's metrics over some other training load scores. LBSS is built second-by-second from Impact Loading Rate. It catches the mechanical cost on easy days, when every footstrike still loads the tissue.

That March 16 easy day posted 72 LBSS against my 42-day rolling average of 83. Below baseline. Still added to my weekly load pile and critical for me to measure.

Why it matters:

This week, open My Training in PowerCenter and watch your daily LBSS bars against your rolling average.

👉 Try it on your next run