“Current Evidence Does NOT Support Zone 2 Training”

Brad Stanfield

Aug 21, 2025

Episode description

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Timestamps:
0:00 Are We Wrong About Zone 2 Training?
0:36 What is Zone 2 Training (in plain English)?
1:29 Two Big Promises of Zone 2 Training
3:04 Zone 2 Controversy & The New Study
4:02 Is Zone 2 Best for Mitochondrial Health?
6:50 Is Zone 2 Best for Fatty Acid Oxidation Capacity?
8:32 The Verdict on Zone 2 for Non-Elite Athletes
9:08 The Importance of High Intensity Exercise
10:19 Key Takeaways and Conclusions

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Here are the links to the research papers referenced in the video:
https://link.springer.com/article/10.1007/s40279-025-02261-y
https://pubmed.ncbi.nlm.nih.gov/31674658/
https://pmc.ncbi.nlm.nih.gov/articles/PMC5766985/
https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0030-1249621
https://journals.physiology.org/doi/full/10.1152/japplphysiol.00030.2001
https://onlinelibrary.wiley.com/doi/10.1002/oby.21206
https://www.sciencedirect.com/science/article/pii/S1728869X23000424
https://www.internationaljournalofcardiology.com/article/S0167-5273(14)00394-5/abstract

Thumbnail by James Kelly
Video edited by Troy Young
Script by John Milliken

The links above are affiliate links, so I receive a small commission every time you use them to purchase a product. The content contained in this video, and its accompanying description, is not intended to replace viewers’ relationships with their own medical practitioner. Always speak with your doctor regarding the content of this channel, and especially before using any products, services, or devices discussed on this channel.

Mindsip insights from this episode:

Increase duration of Zone 2 training to stimulate mitochondrial development

For most people, Zone 2 training provides minimal stress to cellular energy systems and may not be enough to stimulate mitochondrial development unless done for very long durations.

#mitochondria

#zone-2

Reevaluate Zone 2 training for mitochondrial and fatty acid capacity

A new analysis concludes that current evidence does not support Zone 2 training as the optimal intensity for improving mitochondrial or fatty acid oxidative capacity.

#mitochondria

#zone-2

Prioritize 75 minutes of vigorous exercise before Zone 2 training

The recommended protocol is to first complete at least 75 minutes of vigorous-intensity exercise per week before considering adding any Zone 2 training.

#exercise

#zone-2

Prioritize high-intensity training for maximum health benefits in limited time

If you have limited time, you will get a bigger health payoff from high-intensity training than from spending that time in Zone 2.

#exercise

#HIIT

Prioritize VO2 max for improved health outcomes

The link between VO2 max and health outcomes like mortality is much stronger than the link with mitochondrial health, and higher intensity exercise is better for improving it.

#exercise

#VO2-max

Question Zone 2 superiority in fatty acid oxidation

It is not clear which exercise intensity is best for improving fatty acid oxidation, but current evidence does not support the claim that Zone 2 is superior.