Zone 2 for Beginners, Hot Tubs vs. Altitude, & Improving Economy with Sport Scientist Jonah Rosner

Dec 18, 2025

Jonah Rosner, an applied sport scientist with a rich background in professional sports and the Nike Running Performance Lab, dives into running myths. He debunks the idea that beginners should obsess over heart rate zones, emphasizing the value of easy runs for recovery. Jonah explains how heat training mimics altitude benefits, and clarifies the impact of overpronation and sodium on injury risks. He also discusses how intuitive running can enhance technique, revealing that cramping is influenced by fatigue, not just hydration.

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INSIGHT

Heat Can Mimic Altitude Adaptations

Heat training can produce similar blood and cardiac adaptations to altitude when performed over multiple weeks.
Passive hot baths or saunas over 4–5 weeks increased plasma volume, stroke volume, and hemoglobin mass in studies of runners.

ADVICE

Use Post-Run Hot Baths With Progressive Overload

Use passive hot baths or saunas after training to get heat adaptations without compromising quality sessions.
Progressive overload the heat stimulus (increase temperature/duration) across weeks to maintain adaptation gains.

INSIGHT

Form Self-Optimizes With Consistent Running

Distance runners tend to self-optimize running form over years of consistent training.
Forcing specific footstrike or stylistic changes often reduces economy and can raise injury risk.

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Jonah Rosner is an applied sport scientist who spent 10 years working with athletes and teams from all major American professional team sports, particularly the National Football League.

He's a certified running coach and strength and conditioning specialist and he previously partnered with Nike to run the Nike Running Performance Lab in New York City. You can sign up for his Marathon Science newsletter here.

Jonah was also the sport scientist on hand during a fitness retreat I attended last year where I had my VO2 Max measured. Jonah administered the test, which you can watch on Strength Running's YouTube channel.

In this conversation, we myth-bust around the hottest topics in running:

Heat training
How to develop better running economy
Heart rate Zones
Why beginners shouldn't worry about Zone 2
Overpronation
Electrolytes and sodium consumption

If you like this episode, be sure to listen to Facts vs. Fads: Dr. Nick Tiller on Nasal Strips, Organics, Cupping, Detox Diets, & More.

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Thank you LMNT!

A big thanks to LMNT for their support of this episode! They make electrolyte drinks for athletes and low-carb folks with no sugar, artificial ingredients, or colors. They are offering a free gift with your purchase at LMNT. And this does NOT have to be your first purchase. You'll get a sample pack with every flavor so you can try them all before deciding what you like best.

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