Estimated read time: 3.52 minutes (about as long as it takes to read five conflicting creatine opinions on Reddit 🤔)

Hey Performance Nerds! Jonah here. 🤓

Three of you emailed me the same question this month: "Does caffeine cancel out creatine?"

Short answer: no.

A 2022 research review looked at 10 studies on this exact question. 7 out of 10 found zero interference when taken the way runners actually use them.

Here's what you'll learn today:

(Augie has never supplemented anything except whatever falls off my plate. His performance hasn't changed.)

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One study. Nine subjects. Three decades of confusion.

Vandenberghe et al. (1996) found caffeine wiped out creatine's benefit on a leg strength test.

Runners read the headline. The myth stuck.

But look at what they actually tested:

The protocol they tested isn't how any runner takes these supplements.

(Nine subjects. Fewer people than my last group run.)

Caffeine and creatine do interact at the muscle level. But it only matters at doses most runners rarely use.

Darren Candow, one of the most published creatine researchers, explains the mechanism through calcium.

Your muscles contract and relax by shuttling calcium in and out of a storage site.

Caffeine forces calcium out of storage to promote contraction. Creatine helps pump calcium back in for relaxation and recovery.

At high chronic doses, these two pull in opposite directions. A tug-of-war inside your muscle cells. That explains why Vandenberghe's protocol (5 mg/kg caffeine daily during loading) showed interference.

But timing changes everything.

A single pre-exercise caffeine dose peaks in about 60 minutes and fades fast. Creatine operates over hours. By the time creatine is doing its calcium work, caffeine's pull has faded.

Trexler & Smith-Ryan (2015) reviewed how both work in the body: direct interaction is unlikely at standard doses.

The tug-of-war is real. But at normal doses, the two aren't pulling at the same time.

(Two workers using the same machine on different shifts. No conflict.)

Forget one study. Here's what ten show.

Elosegui et al. (2022) reviewed all 10 studies:

7 out of 10 studies found no interference. The 2 that did used the same flawed chronic-loading protocol as Vandenberghe.

Fresh endurance data backs this up. Moesgaard et al. (2024) tested 23 endurance-trained athletes (12 men, 11 women):

Each worked through its own pathway. Neither blocked the other.

Stop overthinking it.

Per Candow, caffeine above roughly 250mg can start to compete with creatine through that calcium tug-of-war. Below that, no blunting.

A typical pre-race dose for a 70kg runner at 3 mg/kg is 210mg. Well under the line.

If you're stacking pre-workout on top of morning coffee, that's where to pay attention.

For reference: I take 5g creatine with breakfast daily and 100-200mg caffeinated gels on race day.

Bottom line: Take both. They compete at the cellular level only at doses and protocols most runners will never use.

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.

EPO has been at the center of some of the biggest endurance doping scandals in sports. But the physiology behind why it works is actually pretty straightforward.

Most of you nailed this one.

The correct answer?

A. It increases red blood cell production, allowing your blood to carry more oxygen to working muscles 🩸🫁 ✅

EPO, short for erythropoietin, stimulates your bone marrow to produce more red blood cells.

More red blood cells means more hemoglobin, which means your blood can carry more oxygen to the muscles that are doing the work. For endurance athletes, oxygen delivery is often the limiting factor for aerobic performance.

That extra oxygen lets runners sustain a higher aerobic output before fatigue sets in.

Here’s how the votes shook out:

🟩 A. It increases red blood cell production, allowing your blood to carry more oxygen to working muscles 🩸🫁 – 209 ✅
⬜️ B. It boosts mitochondrial density in muscle cells, letting you produce energy more efficiently 🔋 – 5
⬜️ C. It raises lactate threshold so you can run harder before fatigue sets in ⚡ – 5
⬜️ D. It increases muscle glycogen storage so you have more fuel during long races 🍝 – 1

A few voters went with lactate threshold or mitochondria.

Those do influence endurance performance, but EPO doesn’t directly change either of them. The performance boost comes primarily from improved oxygen transport, which indirectly supports everything else your aerobic system is trying to do.

Bottom line?

EPO works because it increases your blood’s oxygen-carrying capacity, essentially giving your aerobic engine more oxygen to burn.

I did 4x8 minutes at 345W last Weds. My Critical Power sits at 317W. That's 9% above my metabolic boundary. Spend the reserve, rest, repeat.

CP is the highest power you can hold in a metabolic steady state for a long time. Above it, fatigue accelerates. Below it, you keep going.

Caffeine lowers perceived exertion at a given power. Same 345W, less suffering. It won't instantly change your underlying fitness, and Stryd's CP reflects that. It stays stable as a pacing anchor, race to race. Won't shift mid-effort.

What caffeine can change is how much power you express on race day. Push harder above CP, tolerate more reserve before slowing.

Stryd makes this visible. Set your CP zones and watch where you race.

Why it matters:

On your next hard session, lock in a wattage near CP and notice how it feels.

👉 Try it on your next run