Episode 26 - The fitness that survives: How to Build Durability for 100K and 100-Mile Races

Durability is the ability to preserve your performance as fatigue accumulates during prolonged exercise. While fitness describes what you can do when fresh, durability determines how much of that fitness remains after many hours of running.

In a 100K or 100-mile race, pace can decline because of muscular damage, worsening running economy, reduced force production, poor fuelling and mental fatigue. A durable runner still becomes tired, but their deterioration is slower and more manageable.

Durability is developed through consistent training volume, progressive long runs, selective back-to-back sessions, race-specific terrain, downhill conditioning and strength training. Long runs should also be used to practise realistic pacing, hiking, nutrition and equipment.

The common mistake is trying to prove durability through excessively long or exhausting sessions. Durability is not built by destroying the body in one weekend. It comes from months of sustainable training that can be repeated consistently.

Fitness may carry you through the first half of an ultra. Durability determines what remains for the second.
Key References:

1. Maunder, E., Seiler, S., Mildenhall, M. J., Kilding, A. E., & Plews, D. J. (2021). The Importance of “Durability” in the Physiological Profiling of Endurance Athletes. Sports Medicine, 51, 1619–1628. DOI: 10.1007/s40279-021-01459-0.

2. Jones, A. M. (2024). The Fourth Dimension: Physiological Resilience as an Independent Determinant of Endurance Exercise Performance. The Journal of Physiology, 602, 4113–4128. DOI: 10.1113/JP284205.

3. Millet, G. Y. (2011). Can Neuromuscular Fatigue Explain Running Strategies and Performance in Ultra-Marathons? The Flush Model. Sports Medicine, 41, 489–506. DOI: 10.2165/11588760-000000000-00000.

4. Millet, G. Y., Tomazin, K., Verges, S., et al. (2011). Neuromuscular Consequences of an Extreme Mountain Ultra-Marathon. PLOS ONE, 6, e17059. DOI: 10.1371/journal.pone.0017059.

5. Tanda, G., & Knechtle, B. (2015). Effects of Training and Anthropometric Factors on Marathon and 100 km Ultramarathon Race Performance. Open Access Journal of Sports Medicine, 6, 129–136. DOI: 10.2147/OAJSM.S80637.

6. Bontemps, B., Vercruyssen, F., Gruet, M., & Louis, J. (2020). Downhill Running: What Are the Effects and How Can We Adapt? A Narrative Review. Sports Medicine, 50, 2083–2110. DOI: 10.1007/s40279-020-01355-z.

7. Llanos-Lagos, C., Ramírez-Campillo, R., Moran, J., & Sáez de Villarreal, E. (2024). Effect of Strength Training Programs in Middle- and Long-Distance Runners’ Economy at Different Running Speeds: A Systematic Review with Meta-analysis. Sports Medicine, 54, 895–932. DOI: 10.1007/s40279-023-01978-y.

8. Knechtle, B., & Nikolaidis, P. T. (2018). Physiology and Pathophysiology in Ultra-Marathon Running. Frontiers in Physiology, 9, 634. DOI: 10.3389/fphys.2018.00634.

9. Clark, I. E., Vanhatalo, A., Thompson, C., et al. (2019). Dynamics of the Power-Duration Relationship During Prolonged Endurance Exercise and Influence of Carbohydrate Ingestion. Journal of Applied Physiology, 127, 726–736. DOI: 10.1152/japplphysiol.00207.2019.