Fuelin Sessions Substrate Oxidation Does Not Influence Middle Distance Running Performance: A Randomised Controlled Crossover Trial with Brady Holmer
Dec 11, 2025
Brady Holmer, an exercise physiologist and research assistant to Dr. Rhonda Patrick, dives into the fascinating world of substrate oxidation and its effect on middle-distance running. He discusses a study comparing high-carb and low-carb diets, revealing that while fat oxidation increased after low-carb meals, performance differences were negligible. Brady emphasizes the importance of metabolic flexibility and personalized fueling strategies. With insights on training adaptations and dietary impacts, listeners gain practical advice tailored for their running journeys.
AI Snips
Chapters
Transcript
Episode notes
What Substrate Oxidation Means
- Substrate oxidation means which fuel (fat vs carbs) your body burns and shifts with intensity and availability.
- Metabolic flexibility is the ability to switch fuels based on availability and is common in trained athletes.
Fat Burning ≠ Better Short‑Race Performance
- Being a good fat burner doesn't automatically make you a better endurance performer at race intensity.
- Acute increases in fat use may not improve short-distance (5–10k) performance.
Optimize Your Pre‑Race Meal
- Reduce pre-race fat and match pre-race carbs to body weight; aim higher than the study's ~1.5 g/kg if preparing a carb‑dependent race.
- Keep pre-race fat low (10–15 g) and equate protein between conditions to avoid satiety or GI issues.