Episode 374: Zone 2 Cardio: What the Science Really Says (Pros, Cons & Better Options) with Kristi Storoschuk — Flex Diet Podcast

In this episode of the Flex Diet Podcast, I sit down with my friend Kristi Storoschuk, a PhD candidate in exercise physiology, to unpack her review paper on zone 2 cardio and what the evidence actually shows. We dig into what “zone 2” really means (including lactate thresholds and why common proxies like heart rate and the talk test can miss the mark), where the 80/20 endurance model came from, and why messaging around zone 2 for mitochondrial function, fat oxidation, metabolic flexibility, and health may be overstated, especially for the general population.

Kristi explains why higher intensities often produce equal or better mitochondrial and performance-related adaptations, how training volume and population context change the conversation, and where low-intensity work like walking may still fit.

Sponsors:

Flex 4: Kristi's Top 4 tips for improving aerobic fitness as a recreational lifter: https://flex-diet.kit.com/17ac1beade
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Coming up:

ISSN 2026: https://www.sportsnutritionsociety.org/

Available now:

Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here.

Episode Chapters:

04:04 Why Zone Two Went Viral
09:40 Defining Zone Two Lactate
14:15 Talk Test and Practical Limits
16:43 Does Zone Two Even Matter
21:08 The 80/20 Misapplied
26:14 Origins of Base Training
32:06 Mitochondria Volume vs Intensity
40:08 How Myths Persist Online
44:16 Zone Three Over Zone Two
44:46 Why Some Recover Faster
45:37 Overtraining Study Lessons
49:59 Listen To Output Signals
52:20 How Often To Train
54:42 Short Daily Progressives
57:46 Tabata Reality Check
01:00:19 Walking And Health Outcomes
01:05:23 Mitochondria Versus Performance
01:08:04 Lactate Threshold Beats VO2
01:12:43 Fueling And Final Wrap
01:14:33 Podcast Outro And Disclaimer

Flex Diet Podcasts you may enjoy:

Episode 360: Exploring Aerobic Development & Concurrent Training with Jason Brown
- YouTube: https://www.youtube.com/watch?v=lkqim0EDfec&t=4s
Episode 269: From Mitochondria to Metabolic Health Insights with PhD Candidate Kristi Storoschuk
- YouTube: https://www.youtube.com/watch?v=T9EFRluKt6Q

Connect with :

Instagram: https://www.instagram.com/krististoroschuk/
Website: https://krististoroschuk.com/

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