Empirical Cycling Podcast Watts Doc #59: A Muscle Glycogen Paradox
Dec 3, 2025
Kyle Helson, a NASA scientist and national champion sprinter, joins to explore a fascinating study on muscle glycogen recovery and its surprising impact on high-intensity interval performance. They discuss how delayed carbohydrate feeding can reduce performance, even with equal total calories. Helson explains the complexities of glycogen storage and its significance in sports. They also dive into practical coaching takeaways about post-exercise fueling and discuss how these findings could impact training strategies for cyclists.
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Study Design Focused On Nutrition Timing
- The study used a double-blind crossover design with nutrition, not training, as the intervention.
- They controlled diet and compared immediate vs delayed carbohydrate drinks after high-intensity intervals to test recovery effects.
High‑Intensity Protocol And AMRAP Test
- Day one was 10x2-minute intervals at ~95% Wpeak with 1-minute rests; day two was an all-out AMRAP version of the same intervals.
- This allowed standardized depletion and a sensitive performance test the next day.
Equal Calories, Different Timing
- Participants ate a controlled diet and either received 2.4 g·kg^-1 carbs immediately after exercise or a zero-calorie placebo, then swapped later so total calories matched.
- The design isolated timing of post-exercise carbs while keeping daily energy equal.