Downhill running is one of the most damaging parts of trail racing, not because it is aerobicly hard, but because it places heavy eccentric load on the muscles, especially the quads. In this episode, we explain why downhill running creates so much soreness and fatigue, and why the solution is not to avoid it, but to train it progressively.

The key idea is that downhill training should be treated like strength training for runners: small doses create adaptation, but too much too soon can disrupt the rest of your training. We cover the repeated bout effect, common mistakes runners make, and how to build downhill durability safely through controlled exposure, good technique, and eccentric strength work.

The main takeaway is simple: train downhill like strength work, not like free speed.

Key References:

• Bontemps et al. (2020), review on downhill running, muscle damage, fatigue, and adaptation.

• Coratella et al. (2024), downhill running increases muscle damage markers and impairs force production, with recovery taking several days.

• Tallis et al. (2024), repeated bout effect in downhill running in trained runners.

• McHugh (2003), classic review on the repeated bout effect after eccentric exercise.

• Calvo-Rubio et al. (2024), review of mechanisms behind the repeated bout effect.

• Baxter et al. (2024), once-weekly submaximal eccentric resistance training can still improve neuromuscular function.