Estimated read time: 5.13 minutes (about as long as it takes to explain to your running group why you're taking a "bodybuilder supplement 🤔)

Hey Performance Nerds! Jonah here. 🤓

Runners have avoided creatine for decades because of water weight. The data says they've been leaving free performance on the table.

Last week's carousel on creatine for runners blew up. You asked for the full breakdown. Here it is.

Here's what you'll learn today:

(Augie, my dog, has never taken creatine. He still somehow outruns me to the front door. Genetics are unfair.)

The world is loud right now. Screens, notifications, everyone with an opinion. But every day I lace up, I get an hour where none of it reaches me. Just breathing, footsteps, and whatever road is in front of me.

Running didn't just make me faster. It taught me how to handle everything else. That hour (or much longer) is non-negotiable. And anything that helps me protect it is worth paying attention to.

If you feel the same way, hit reply and tell me what running gives you beyond the finish line. I would love to hear your story!

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

Yes, creatine pulls water into your muscle cells. You might see the scale tick up 1-2 lbs.

But that's not the full picture.

Creatine typically decreases fat mass by roughly 0.5-1.0 kg. Net composition often shifts in your favor: more muscle, more cellular hydration, less fat.

The runners afraid of "gaining weight" are looking at the wrong number.

Your muscles can't always wait for oxygen.

Your body stores creatine as phosphocreatine (PCr). When you surge up a hill or kick for the finish, PCr rapidly rebuilds ATP.

That's your instant energy currency.

Creatine also pulls water into cells. That cellular swelling supports muscle growth and recovery.

If your training is all easy miles, creatine is probably neutral. But if you do workouts, hills, strides, or lift, here's where it matters.

Creatine is an anti-inflammatory agent. It reduces signs of muscle damage and inflammation after long events like 30-km races and Half-Ironmans.

Yamaguchi et al. (2024) found that just 3g daily for 28 days reduced day-after soreness.

Less damage between hard sessions may mean more consistent quality workouts. (That's the real compound interest.)

Creatine is osmotic. It helps maintain plasma volume when you sweat.

Your blood stays thinner. Heart rate drift slows.

And despite what you've heard, cramping doesn't increase with creatine. If anything, the incidence actually goes down.

If you train through summer blocks or race in the heat, creatine acts like built-in hydration insurance.

Early research suggests creatine aids cognitive function during sleep deprivation and at altitude. The effects are mixed.

Worth considering for ultras, altitude races, or those weeks when sleep falls apart. (We've all been there.)

Action step: You're already taking it daily for the other five reasons. If brain benefits show up, that's a bonus.

This is where the evidence gets strong.

Creatine fights sarcopenia, the age-related loss of muscle mass that quietly steals your speed after 40. It may also preserve bone density when combined with resistance exercise.

Desai et al. (2024) ran a research review on creatine plus resistance training. Result: 1.14 kg more lean body mass and 0.88% less body fat compared to training alone.

If you're over 40 and strength training (you should be), creatine makes that training more effective. Think durability, not size.

Your muscles run on stored fuel. Creatine taken with carbs enhances that storage.

Your muscles increase glucose transport in the first 24 hours of recovery, pulling more fuel into the tank.

Research on elite cyclists showed creatine plus carbs during a 120-km time trial improved closing sprint power. The small mass increase didn't hurt performance.

A fuller fuel tank at the start, and a better finishing kick when it counts.

Creatine helps your muscle cells cycle calcium faster. Better calcium cycling means better force development under fatigue.

One study found that the fatigue threshold increased by roughly 14.5% in college-aged women. Creatine may also reduce the oxygen cost of exercise.

On race day: you may hold pace longer before your form breaks down. Mile 22 posture instead of mile 22 shuffle.

No complicated loading phases. No timing gimmicks.

Bottom line: Creatine builds durability, not size. The water weight on the scale won't slow your 10K. The recovery, heat tolerance, and late-race form might speed it up.

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.

Double-threshold days have become borderline mythical in endurance circles. Some think they’re magic. Others think they’re reckless.

Most of you understood what actually makes them work.

The correct answer?

A. Lower HR/lactate/RPE drift per session, letting you accumulate more weekly “controlled” threshold volume 🧪📉 ✅

When you split threshold work into two sessions, each bout starts fresh. Lactate, heart rate, and perceived effort stay more stable, which lets you accumulate more high-quality work without tipping into supra-threshold territory.

The win isn’t a bigger single-session stimulus. It’s better control and more repeatable volume across the week.

This is why elite systems using double threshold are obsessive about lactate caps. The goal isn’t to go harder. It’s to stay aerobic while stacking sustainable work.

Here’s how the votes shook out:
🟩 A. Lower HR/lactate/RPE drift per session, letting you accumulate more weekly “controlled” threshold volume 🧪📉 – 172 ✅
🟨 B. Higher VO₂max stimulus, because two sessions give you two chances to hit max oxygen uptake 🫁⚡️ – 29
⬜️ C. Better glycogen-depletion signaling, because the second session is always “train low” 🧠🍚 – 17
🟨 D. A bigger total stress response, because frequency matters more than duration for endurance adaptation 🔥🔁 – 51

A surprising number of you went with “bigger stress response.”

But threshold training isn’t about smashing the system. It’s about precision. Drift upward and you’re no longer training the same physiology.

Bottom line?

Double threshold works because it protects intensity control while expanding total quality volume. It’s not about going harder, it’s about staying aerobic longer and doing it again tomorrow.

I threw in three 30-second surges at the end of my long run last Sunday. Power jumped from 240W to 360W almost instantly.

My Critical Power right now is 317W, so that surge put me well above my sustainable ceiling. Heart rate? Barely budged for the first 15 seconds.

That gap is your phosphocreatine system at work. PCr is stored energy in your muscles that fires immediately during hard efforts. It's fast, powerful, and burns out in about 10-15 seconds. Creatine supplementation (this week's topic) supports exactly this system.

Stryd’s Critical Power shows where your sustainable ceiling sits. It is the highest power you can hold without rapidly fatiguing.

Go above CP and you are no longer in steady-state territory. You are working into the limited capacity that exists above it.

Those surges I did? Each one tapped into that capacity fast because I was well above CP. The harder and longer you sit above it, the sooner fatigue catches up.

Why it matters:

Next time you surge, watch how fast power rises relative to CP. That’s high-intensity work on display. That's your phosphocreatine system on display.

👉 Try it on your next run