The Strength Running Podcast · Jason Fitzgerald

The Limits of Endurance: Dr. Andrew Best on Running's "Metabolic Ceiling"

·1 hr 5 min·4 clips

Best says the two-and-a-half-times ceiling may not kick in until around 30 weeks.

Jason Fitzgerald introduces episode 442 and welcomes Dr. Andrew Best to the show. He frames the conversation around helping runners get better. Once the interview gets going, the focus turns to how underfueling affects training. Dr. Best argues that carrying a little extra body mass is often less of a problem than being even a couple hundred calories short. He ties that shortfall to immediate performance loss. He then extends the point to longer term effects. Carbohydrate depletion comes up early because glycogen is one of the first things to run low when intake falls behind output. From there, the discussion moves into durability. Underfueling can affect bone density, testosterone and estrogen levels in both men and women, and recovery. Dr. Best links that chain to stress fractures and weaker adaptation. The conversation keeps circling back to the same practical point. Runners who train hard need to eat enough, especially enough carbohydrates. He says carbohydrates are the body's preferred fuel for higher intensity exercise. Jason then asks about the best macro split for all the energy required. Dr. Best notes that their study did not examine the carbohydrate fat breakdown directly and says the answer is probably individual. The discussion stays accessible even when it gets technical, translating physiology into everyday training choices runners can actually use.

As heard by us

A practical look at why endurance can have a fuel problem before it has a grit problem.

Dr. Andrew Best turns a familiar running worry into something more useful by focusing on where endurance can start to fall apart, and on what runners miss when they think only about body weight.

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Why you'd press play

Press play for a grounded take on why hard training calls for real carbohydrate support.

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