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, RPE, 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 in the race. Pacing is the art of managing your speed, effort, walk breaks, fuel, and terrain to minimise excessive slowing and preserve enough energy to finish strong.
Poor pacing leads to big slowdowns, excessive fatigue, injury risk, or getting cut off by time limits. Good pacing is often the difference between a race you're proud of and one you'd rather forget. And the biggest single mistake most ultra runners make — especially in their first race — is starting too fast.
Key Insights from Research
- Banking time is a myth. Research consistently shows that runners who start fast and try to "bank" time almost always pay for it later with a far greater slow-down. Even pacing or slight negative splits (running the second half faster) lead to better outcomes in endurance events.
- Faster runners 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, preserving quad strength for later.
- Run-walk strategies help manage fatigue. Planned walk breaks can extend endurance, reduce muscle damage, and help maintain form over many hours.
- Nutrition and pacing are interlinked. Over-pacing early reduces digestive efficiency, making it harder to absorb carbohydrates when you need them most.
Pace vs. Effort: Why RPE Matters More on Trails
On roads, pace per kilometre is a useful guide. On trails with variable terrain, elevation, and conditions, it becomes almost meaningless. A 7 min/km pace on flat tarmac is completely different to 7 min/km on a steep fell climb or boggy moorland.
Rate of Perceived Exertion (RPE) is a far more reliable tool for trail ultra pacing. RPE is simply a 1–10 scale of how hard you feel you're working, where 1 is almost no effort and 10 is all-out maximum. For ultra pacing, use this rough framework:
- First quarter of race: RPE 4–5 (easy-to-moderate, controlled, conversational)
- Middle section: RPE 5–6 (moderate, sustainable, still able to eat and drink comfortably)
- Final quarter: RPE 6–7 (harder as fatigue builds, but controlled — not survival mode)
If you can't hold a conversation in the first quarter of the race, you're working too hard. If your effort on a climb feels like 8–9/10, you're burning matches you don't have yet. The goal is to reach the final quarter with something left to give.
Grade Adjusted Pace (GAP): A Useful Tool for Hilly Terrain
Many modern GPS watches (Garmin, Coros, Suunto) now calculate Grade Adjusted Pace (GAP) — an effort-equivalent pace that accounts for the gradient you're running on. On a steep uphill, your GAP will show a much faster equivalent pace than the actual pace displayed, helping you understand your true effort level relative to flat running.
GAP is useful for planning and for training. If you know your comfortable flat-pace equivalent (say, 6:30 min/km at RPE 5), you can use GAP on your watch during hilly runs to check that you're not working too hard on climbs without realising it. Use it as a guide, not a rigid target — trail conditions, weather, and how you feel on the day all matter more than a number on a screen.
A Pacing Framework for Ultra Runners
1. Set a Conservative Target — Then Go 10% Slower
Whatever pace you think is sustainable for the full distance, add a meaningful buffer. Most first-time ultra runners significantly overestimate what they can maintain. If anything feels like a stretch target, it probably is. Going 10–15% more conservatively than feels necessary in the first third of the race is almost always the right call — and almost always rewards you in the final third.
2. Use Race Segments, Not the Whole Distance
Break the ultra into mini-goals: just get to the next aid station, the next summit, the next 5 km. Many coaches call this "run the mile you're in." This approach is psychologically powerful and keeps you from getting overwhelmed by how far you still have to go.
3. Walk Uphills — Proactively, Not Reactively
Walk the climbs before you need to, not after you're already struggling. Hiking uphills efficiently often costs very little time compared to running them, while saving significant quad and cardiovascular energy for later in the race. The runners who walk uphills confidently and early often overtake those who ran the early climbs and are now suffering.
4. Protect Your Downhills
Descents are where quad damage accumulates. Aggressive downhill running early in the race — especially on steep, technical terrain — can leave your legs so damaged that you can barely descend in the final miles. Run downhills within yourself. Let the terrain help you, but don't bomb it when your quads are fresh. The time you save early rarely compensates for what you lose late.
5. Use Planned Walk Breaks from the Start
Don't wait until you have to walk — schedule it. Planned walk intervals before fatigue sets in are far more effective than walking because you've fallen apart. A simple run-walk rhythm from the beginning normalises walking and removes the psychological defeat of "having" to stop and walk. Walking is strategy, not failure.
6. Stay Flexible and Adjust in Real Time
If you're feeling strong at the halfway point, you can cautiously increase effort. If you're struggling ahead of schedule, slow more or extend walk intervals. Watch your body more than your watch. The plan serves you — you don't serve the plan.
Poles: A Pacing Tool as Much as a Physical One
Running poles can reduce the load on your legs by 20–25% on uphills and allow a faster, more efficient hiking pace. Use them proactively — don't wait until your legs are gone before reaching for them. Poles also help maintain upright posture as fatigue sets in, which reduces energy waste and lower back strain over many hours.
Stow poles safely when passing through narrow gates, crossing stiles, or on sections of technical scrambling where you need your hands free. Practise stowing and deploying them smoothly in training — fumbling with poles mid-race wastes time and energy.
Pacing Strategies by Runner Type
For Faster / Experienced Ultra Runners
- Avoid chasing others early — find your own rhythm from the gun.
- Use brief walk breaks (<60 seconds) at steep climbs, aid stations, and in heat zones.
- Focus on consistent relative effort using RPE and GAP rather than rigid pace targets.
- Reserve any real surging for the final 20% of the race, not before.
Example plan: First 15% — settle, hold back. Middle 60% — steady relative effort, terrain-adjusted. Final 25% — controlled, push what you can from the last 10%.
For Slower / Midpack Ultra Runners
- Be more conservative than feels comfortable early — the race rewards patience.
- Use run-walk from the start: run 6–8 min / walk 1–2 min is a solid, proven starting point.
- Walk every significant uphill — this is almost always more efficient than running them.
- Accept and plan for more slowing in the final third; build this into your time estimates.
Example plan: Run 6–8 min / walk 1–2 min early. After halfway shift to run 4–5 min / walk 1–2 min. Final quarter: run 3 min / walk 1–2 min, or what feels sustainable.
For Walkers / First-Time Ultra Finishers
- Walking efficiency matters enormously over many hours — stand tall, engage your arms, and maintain a purposeful stride.
- Use "power hiking" on flat and rolling terrain — it's faster than you think when done well.
- Set a pace you know you can sustain all day — do not go fast early just because you feel good.
- Short jogs on gentle downhills and flat sections can be a useful gear change without overloading the legs.
Aid Station Pacing
Aid stations are not just for refuelling — they're a chance to reset mentally and physically. But they can also be time traps. Think of stopping the clock mentally: take what you need, refuel, assess, and move. Three to five minutes is usually enough at standard stations. At drop bag points (like Troutbeck on The Lap), allow 8–15 minutes — but set a mental limit and stick to it.
Eat on your feet where possible. Sitting down for more than a minute or two makes it significantly harder to get moving again — your legs stiffen, your mind relaxes, and the temptation to stay seated grows. Keep moving, even if slowly, while you eat and drink.
If the Race Goes Into Night
If your race is long enough to run into darkness, your pacing needs to adapt. Perceived exertion increases at night — the same effort feels harder in the dark, and sleep deprivation from an early start compounds this. Head torch light flattens terrain, making it harder to read the ground and increasing trip risk.
Slow down proactively once darkness falls, even if you feel okay. Take shorter, more deliberate steps on technical terrain. Use your poles more actively. Eat something warm and savoury if available — it's grounding and comforting when your brain is foggy. If you feel very sleepy, a 10–15 minute sleep at an aid station is better than staggering dangerously or making poor navigation decisions.
Common Pacing Mistakes
- "Banking time" early: This almost always backfires. The research is clear: starting 10% too fast often leads to 30–40% slower in the final miles. Don't do it.
- Ignoring terrain: A fast pace on flat roads that matches what you can do uphill depletes energy quickly. Slow for climbs, use GAP to check real effort.
- Overly rigid walk/run splits: Conditions change. Be willing to adjust your ratio based on how you feel, the terrain, and the heat.
- Neglecting walking technique: A shuffling, hunched walk wastes energy over many hours. Stand tall, drive with your arms, and make each walk count.
- Waiting too long at aid stations: Five minutes feels short, but across 6–8 stations adds up quickly. Be efficient.
Pacing, Nutrition, and Hydration: They're Inseparable
Research shows that over-pacing compromises gastrointestinal function — blood is redirected away from the gut toward working muscles, reducing your ability to absorb carbohydrates. This creates a vicious cycle: go too hard, gut shuts down, can't fuel, performance collapses further. Keep your effort moderate enough that you can eat and drink comfortably. Use walk breaks and aid station stops as deliberate opportunities to refuel properly.
Final Tips
- Practise your pacing strategy in training — do some long runs at race-day effort, not just distance.
- Start your walk breaks on the uphills before you need to, not after.
- Break the race into segments. Focus on what's immediately ahead.
- Listen to your body. If form degrades or fatigue comes earlier than expected, ease up sooner rather than later.
- Train your walking. Most ultra runners massively underestimate how much of their race they will walk — and how much it matters to walk efficiently.