Training Science Podcast ZONE 2 SHOWDOWN - with Dr Kristi Storoschuk & Prof Paul Laursen
Aug 8, 2025
Kristi Storoschuk, a PhD candidate whose innovative research challenges traditional views on Zone 2 training and fasting, joins Professor Paul Laursen. They dissect the myths surrounding fasting and the effects of nutrition on athletic performance, emphasizing the differences between human and rodent studies. The duo discusses the significance of mitochondrial health, the potential benefits of low-carb diets for athletes, and the dual challenges faced during an 80K ultra trail run, all while advocating individual experimentation in training and nutrition for optimal results.
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Rodents Show Glycogen Loss Not Seen In Humans
- Kristi explains rodents deplete muscle glycogen during fasts, linking to AMP/ADP accumulation and AMPK activation.
- Humans preserve muscle glycogen even after 72-hour fasts, so the rodent mechanism likely doesn't translate.
Personal Experience With 48-Hour Fast
- Kristi Storoschuk tried a 48-hour fast and found it tolerable but disliked going to bed hungry.
- She also completed a CrossFit workout after a 36-hour fast and reported feeling fine.
Intensity, Not Zone 2, Drives Mitochondrial Gains
- Kristi's review found little evidence that Zone 2 uniquely triggers mitochondrial biogenesis in general populations.
- Across studies, higher intensities usually matched or exceeded Zone 2 for mitochondrial and fat-oxidation adaptations.
