Pacing an ultramarathon is one of the most critical — and most misunderstood — skills in ultra running. Updated for 2025 with the latest thinking on effort management, walk-run strategies and late-race survival.
What Is Ultra Pacing — and Why It Matters
When you run an ultramarathon, one of your biggest challenges is how to distribute your effort over many hours so you don't collapse late. Pacing is the art of managing your speed, effort, rest, walk breaks, fuel, and terrain to minimise excessive slowing and preserve energy.
Poor pacing leads to big slowdowns, excessive fatigue, injury risk, or getting cut off by time limits. Good pacing makes the difference between a strong finish and a painful crawl.
Key Insights & Research Findings
- Faster runners tend to pace more evenly — Elite and higher-performing runners show less variation in pace; they avoid going too hard early.
- Elevation strongly affects pacing — Better finishers run downhills faster (relatively) and ease up more on uphills.
- Positive pacing (gradual slowing) is common — Many ultra runners gradually slow over the course, especially on tougher terrain.
- Run-walk strategies help manage fatigue — Planned walk breaks can extend endurance, lower muscle damage, and help maintain form.
- Nutrition and pacing are interlinked — Over-pacing early may reduce digestive efficiency and impair carbohydrate intake.
- Terrain-specific pacing gaps widen late — Faster runners maintain performance better on downhill segments as the race progresses.
A Simple Pacing Framework
1. Estimate a Sustainable Base Pace
Start with what you believe is a pace you can hold for many hours — comfortably hard, not your fastest. Allow for some buffer when race day conditions are tougher than training.
2. Use Race Segments Rather Than Thinking of the Whole Thing
Break the ultra into mini-goals: to the first aid station, to the next climb, or between 5–10 km blocks. Many coaches call this "run the mile you're in."
3. Factor in Terrain and Hills
On climbs, slow down (or switch to walking) early so your heart rate doesn't spike unsustainably. On descents, you can make up time — but don't go all out and wreck your quads. The difference between fast and slow runners is often greatest in downhill segments late in an ultra.
4. Accept Some Slowing — But Control It
Don't expect to run at the same pace nonstop. Small gradual decline is normal, but if your pace craters, that's a pacing mistake.
5. Use Planned Walk Breaks
Instead of waiting until you have to walk, schedule brief walk intervals before fatigue hits. This helps reset fatigue and maintain form.
6. Be Flexible and Adjust Mid-Race
If you're feeling strong, pick up pace. If you're fading, slow more or increase walk intervals. Keep watching your body more than your splits.
Pacing Strategies by Runner Type
For Fast / Experienced Ultra Runners
- Avoid overzealous starts — try to maintain steady relative intensity.
- Use brief walk breaks (<30 seconds) for aid stations, steep climbs, or heat zones.
- Use surges intentionally on easier terrain — but maintain enough reserve.
- Keep smooth transitions; too much fluctuation is less efficient.
Example plan: First 10–15%: settle in, don't chase others. Middle 60%: hold consistent relative effort, adjust for terrain. Final 25%: controlled slowing, push when energy allows.
For Slower / Midpack Ultra Runners
- Err on the side of conservatism early — don't try to keep up with faster runners.
- Use run-walk from the start: run 6–8 min / walk 1 min is a solid starting point.
- Walk climbs aggressively — this is often more efficient uphill.
- Allow more built-in slowing: accept that your pace will drop more toward the end.
Example plan: Start with run 6–8 min / walk 1 min. After halfway, shift to run 4–5 min / walk 1 min, then 3 min / walk 1 min as fatigue increases.
For Walkers / Ultra Walk-Joggers
- Optimise walking efficiency and gait — walking economy matters over many hours.
- Set a steady walking pace you can sustain rather than going fast early.
- Use "power walking" on flatter terrain.
- Walk uphills; on descents, transition into a light jog or fast walk.
Common Pacing Mistakes
- Starting too fast ("banking time"): Many ultra runners push early to build a buffer — this often leads to collapse later.
- Ignoring terrain effects: Treating the course as flat while ignoring hills drains energy quickly.
- Overly rigid walk/run splits: Some try to stick to exact ratios even when conditions change. Be flexible.
- Neglecting walking technique: Poor walking gait wastes energy, especially when walking makes up a large share of time.
- Letting pace drift uncontrolled: Without regular checks or micro resets, your form and speed will degrade.
Integrating Pacing with Nutrition & Hydration
Pacing doesn't stand alone. Research shows that over-pacing can compromise gastrointestinal function, reducing carbohydrate intake and harming later performance. Keep your effort moderate enough that you can still take in food and fluids. Use walk breaks, aid stations, or slowed segments to eat, drink, and reset.
Final Tips
- Practice your pacing strategy in training — don't wait until race day.
- Use aid stations wisely — slow down, refuel, walk while eating.
- Break the race into mental segments — focus on what's immediately ahead.
- Listen to your body — if form degrades or you feel early fatigue, ease up sooner.
- Train walking — many ultra runners underestimate how much time they will walk.