The Strength Running Podcast The Limits of Endurance: Dr. Andrew Best on Running's "Metabolic Ceiling"
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Jan 22, 2026 Dr. Andrew Best, a biological anthropology professor and endurance researcher, dives into his groundbreaking study on the metabolic ceiling in ultrarunners. He reveals that most athletes can sustain energy outputs near 2.5 times their basal metabolic rate over extended periods. The conversation explores the importance of proper fueling, the risks of underfueling, and how to maximize gut absorption with carbohydrate blends. They also touch on the physiological limits of endurance running, including central fatigue and muscle damage, and why training enlarges your 'engine'.
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A Predictable Long-Term Metabolic Ceiling
- Humans appear to have a common long-term metabolic ceiling near 2.5× basal metabolic rate (BMR).
- This ceiling limits sustainable daily energy expenditure over months without losing mass or accruing an energetic debt.
The Ceiling Appears Over Months, Not Days
- The 2.5× BMR limit emerges over months — roughly around 30 weeks — not days.
- Athletes can exceed the ceiling short-term (weeks) but risk body-mass loss and must later recover to return to equilibrium.
Appalachian Trail Example Of Short-Term Excess
- One study subject ran the Appalachian Trail pushing a metabolic multiple near 4× BMR for 46 days and lost significant body mass.
- That effort required paying back the energetic debt afterward through recovery and refueling.
