The original "Metabolic Map" I created in 2013 organized exercise metabolism around substrate utilization and muscle fiber recruitment, illustrating how the body transitions from fat to carbohydrate use as intensity increases.

This model helped me and many others translate complex laboratory findings into practical guidance for training and performance.

Now, I believe that it is time to evolve the concept..

Through years of research, as well as performance and clinical work with world-class athletes and patients, this has led to an updated model (2026), representing a conceptual shift.

Rather than questioning what the body burns, I began to question whether the system itself is in balance.

Exercise metabolism is reframed as a continuum of metabolic states, from equilibrium to overload, governed by the relationship between glycolysis and mitochondrial capacity.

Lactate emerges as a central proxy of this balance, reflecting the system’s ability to match production with clearance.

This concept and article have taken longer to articulate than anticipated, but tomorrow I’ll share the new model in my substack article.