You have likely seen the term 80-20 running: a training approach where 80% of runs are easy, and 20% are hard. But is this an infallible rule as people present it on social media, or are there times when you may run more hard workouts - or more easy runs? We discuss the nuance of training intensity distribution with sport scientist Jonah Rosner.

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In this episode, you will learn:

✅ What is 80-20 running?

✅ What does 20% of your training hard actually look like?

✅ Polarized vs pyramidal training

✅ Why so much of your training is easy running

✅ How to approach training intensity in a marathon build

✅ The load differences of different training paces

Who should and should not use 80-20 training

About our guest:

Jonah Rosner is a sport scientist, strength coach, and running performance coach based in Brooklyn. He spent the past decade working with athletes across every major American pro sport, including serving as the Applied Sport Science Coordinator for the Houston Texans in the NFL, one of the youngest sport scientists in league history.

Jonah now focuses on helping everyday runners train with the same clarity and structure used in elite environments. He partnered with Nike to run the Nike Running Performance Lab NYC, where he used advanced testing and technology to build individualized strength and marathon training programs.

Today, Jonah creates some of the most widely shared science-backed running content online. His free weekly newsletter, Marathon Science, breaks down training, strength, fueling, and performance into simple takeaways runners can use immediately. Subscribers get free tools like his daily nutrition guides, carb-loading cheatsheet, and strength-for-runners resources.

You can join the newsletter at: https://marathonscience.beehiiv.com/ — it’s packed with practical insights grounded in real sport science.

If you enjoyed this episode, you may also like:

🎧 Running for Health vs Performance (14 Nov 2025)

🎧 Is it Bad to Run in Zone 3? (12 Jan 2024)

🎧 Understanding Different Marathon Training Plans and Methodologies (24 Jan 2025)

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Episode 2: Zone Two Training and Heart Rate Monitoring