Episode 2 - Why Downhill Running Destroys So Many Ultra Races

Most ultra runners don’t lose races on the climbs—they lose them on the descents.

In this episode of The Trail Running Briefing, we break down why downhill running causes so much damage despite feeling easy at the time. You’ll learn how eccentric muscle loading silently destroys the quads, why this fatigue is delayed and deceptive, and why cardiovascular fitness alone won’t protect you late in an ultra.

We also cover the most common mistakes runners make in training avoiding downhills, underestimating their impact, and treating them as free speed and what actually works instead. From smarter downhill exposure to eccentric strength work and technique adjustments, this episode gives you a simple mental model to understand why so many races fall apart after the halfway point.

Key takeaway: If you don’t train your quads for the downhills, the race will.

Understand your training. Run better.

Key references:

• Eston, R., Byrne, C., & Twist, C. (2003)
  Muscle function after exercise-induced muscle damage and rapid adaptation.
  Journal of Sports Sciences
• Chen, T. C., Lin, K. Y., Chen, H. L., Lin, M. J., & Nosaka, K. (2011)
  Comparison in eccentric exercise-induced muscle damage among four limb muscles.
  European Journal of Applied Physiology
• Giandolini, M., et al. (2016)
  Impact of downhill running on neuromuscular fatigue and running economy in trail runners.
  Journal of Applied Physiology
• Vernillo, G., Giandolini, M., Edwards, W. B., Morin, J. B., Samozino, P., & Millet, G. Y. (2017)
  Biomechanics and physiology of uphill and downhill running in mountain races.
  Sports Medicine
• Millet, G. Y., & Lepers, R. (2004)
  Alterations of neuromuscular function after prolonged running, cycling and skiing exercises.
  Sports Medicine
• Nicol, C., Komi, P. V., & Marconnet, P. (1991)
  Fatigue effects of marathon running on neuromuscular performance.
  Scandinavian Journal of Medicine & Science in Sports
• Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004)
  Factors affecting running economy in trained distance runners.
  Sports Medicine