Ultra-Trail Pacing: The Complete Guide
Ultra-trails are not won in the first hour, but they can be lost there. Pacing is the most critical and underestimated skill.
What is ultra-trail pacing?
Unlike road marathons where steady speed matters, trail pacing is about constant effort. Terrain and elevation make speed an unreliable metric.
The 3 pillars of pacing
- Relative intensity: Run at 60–70% of max heart rate regardless of slope.
- Terrain adaptation: Hike efficiently on steep climbs to preserve glycogen.
- Durability: Save energy for the real race that starts after halfway.
Why 90% of runners fail their pacing
The classic mistake is an extreme positive split: starting too fast, feeling great, then collapsing.
- Excessive glycogen depletion: You burn sugar instead of fat too early.
- Early muscular fatigue: Irreversible loss of efficiency.
- Digestive issues: Blood is diverted away from the stomach.
If you feel too slow at the start of an ultra, you are probably still a bit too fast.
How to build your pacing strategy
1. Vertical Ascent Speed (VAM)
In the mountains, elevation dictates time. Knowing your sustainable VAM is more reliable than flat pace.
2. The race roadbook
Never start without a plan. Break the race into logical segments between aid stations.
3. Climbs, descents, and flats
- Climbs: smooth effort, control breathing.
- Descents: avoid early damage, stay relaxed.
- Flats: keep jogging, even very slowly.
Common mistakes to avoid
- Following others at the start
- Wasting time at aid stations
- Trying to make up lost time
Pacing FAQ
Should I use heart rate?
Yes, especially early on. Beware of cardiac drift later.
How do I pace at night?
Perception is distorted. Trust your metrics and nutrition.
Should I hike early?
Absolutely if the slope requires it. Hike early, run late.
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