VO₂max measures your maximum aerobic capacity, but ultra races are not performed anywhere near that intensity. What decides performance is not how big your “engine” is, but how efficiently and sustainably you can use it for many hours.

Ultra success depends on factors like lactate threshold, aerobic efficiency, fueling tolerance, muscular durability (especially for long descents), and disciplined pacing. Chasing VO₂max through frequent high-intensity sessions often adds fatigue without improving race-day performance.

Instead, effective ultra training prioritises sub-threshold work, long aerobic sessions, strength for resilience, and practicing nutrition under load. In ultras, the winners aren’t the runners who can go the hardest. They’re the ones who slow down the least.

Key references:

• Joyner, M. J., & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology.
• Bassett, D. R., & Howley, E. T. (2000). Limiting factors for maximum oxygen uptake and endurance performance. Medicine & Science in Sports & Exercise.
• Seiler, S. (2010). What is best practice for training intensity distribution in endurance athletes? International Journal of Sports Physiology and Performance.
• Stöggl, T., & Sperlich, B. (2015). Polarized training improves endurance performance variables. Frontiers in Physiology.
• Brooks, G. A. (2020). The lactate shuttle theory. Cell Metabolism.
• San Millán, I., & Brooks, G. A. (2018). Metabolic flexibility and performance. Sports Medicine.
• Vanhatalo, A., Jones, A. M., & Burnley, M. (2011). Critical power: a key concept in endurance performance.