Mastering Ultra‑Marathon Pacing: Lessons from the World's Toughest Races
The moment the desert sun slipped over the dunes
The low hum of wind-blown sand stays with me from that first stage of a seven-day desert race. Lacing up before dawn, I faced a wavering line of heat-shimmer on the horizon, the kind of landscape where finishing 30 km feels uncertain. I set off too fast, caught up in that instinctive “lead from the gun” energy. By the 8 km mark, the sand had turned into a heavy, punishing weight beneath my feet, and my heart was thundering harder than my stride could manage. I eased back, then stopped altogether, and sat for a while in the heat, just listening.
That moment of stillness taught me something essential about pacing: speed is a tool, not a rule. The desert speaks (as do mountains, heat, and weather) and if you ignore that voice, you’ll pay the cost.
Why pacing matters more than you think
The science of effort
Your body’s ability to sustain high-intensity effort is finite. Think of it as a glycogen budget. Cross above your lactate threshold (often called tempo pace), and you’re spending faster than you can replenish. The result is early fatigue, and in harsh conditions like heat, the risk climbs further. Research into marathon and ultra-marathon runners shows that running at a steady-state pace (roughly 70-80% of maximal aerobic capacity) increases fat oxidation, preserves glycogen stores, and keeps your body cooler.
The mental side-effect
Beyond the physiology, pacing is a mental anchor. A well-chosen zone acts like a permission slip. It frees you to stay composed, zero in on your form, and take in the landscape instead of fixating on splits. Elite ultrarunners know this mental spaciousness as “running your own race”.
Turning the concept into a personal coaching plan
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Identify your personalised pace zones. Take a recent long run (15-20 km) and capture your average heart rate and sense of effort. From that data, define three zones:
- Easy (recovery), 80-90% of max HR: use for warm-ups, cool-downs, and long steady miles.
- Tempo (lactate threshold), 90-100% of max HR: the range for 10-20 km runs that build endurance.
- Hard (race-pace), 100-110% of max HR: reserved for short intervals, hill repeats, or the closing stages of a race.
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Build adaptive training weeks. Your first week sets the baseline at 70% of your usual mileage. In week two, push the long run up by 10% while holding your easy runs steady. Week three brings a tempo segment (20% of the long run) right at the top of your threshold zone. This setup lets you auto-adjust as you listen to your body. Experienced runners know to ease off when the temperature climbs.
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Create custom workouts that reflect real-race terrain. Does your race include a long, flat desert stretch? Run 30 km at the easy-to-tempo boundary. Mountains on the course? Add hill repeats in the hard zone for 2-3 minutes each, with easy jogging to recover between.
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Use real-time feedback to stay inside your zones. A chest-strap or wrist monitor displaying heart-rate and pace will catch you the instant you creep into the hard zone by accident. A quiet vibration or color-coded feedback (green = easy, amber = tempo, red = hard) keeps you accountable without disrupting your rhythm.
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Draw from community workouts. Runners everywhere share their favorite pace-zone workouts in online forums. Find a proven 12-kilometre tempo set, adapt the intervals to your zones, and try it out. Following how others have improved can spark ideas for refining your own approach.
A simple, forward-looking workout to try today
“The beauty of running is that it’s a long game, and the more you learn to listen to your body, the more you’ll get out of it.”
The 12 km progressive pace run
| Segment | Distance | Target effort (HR % of max) | Description |
|---|---|---|---|
| 1 | 2 km | 85% (easy) | Warm-up, relaxed, focus on breathing. |
| 2 | 4 km | 95% (tempo) | Hold a steady, comfortable effort. You should be able to speak in short sentences. |
| 3 | 2 km | 100% (hard) | Pick up the pace just enough to feel the legs working harder; think of a short race-finish surge. |
| 4 | 4 km | 85% (easy) | Cool-down, let the heart-rate drift down, enjoy the scenery. |
How to run it:
- Mark the start of each segment on a GPS watch or a simple phone app.
- Keep a quick glance at your heart-rate; if you cross the colour threshold, adjust your effort.
- After the run, note how you felt in each zone. This is the first step in building a personal pacing library.
Once you complete this run, you’ll have felt all three zones in one go, exactly as a race will require you to shift gears while staying composed. In the weeks ahead, you can lengthen the tempo block, throw in hill repeats, or trade flat ground for sand or trail, based on what your next race demands.
Takeaway
Pacing isn’t the province of elite runners. It’s a learnable skill built on data, clear zone definitions, and tuning in to your body as you run. Think of each run as a mini-race, complete with easy, tempo, and hard phases. Show up on race day with this practice under your belt, and you’ll feel prepared, strong, and ready to trust the terrain instead of fighting it.
Ready to start? Try the 12 km progressive pace run today and see how it feels.
References
- 2015 Marathon des Sables (MdS) Results – iRunFar (Blog)
- Nikki Kimball’s 2014 Marathon des Sables Race Report – iRunFar (Blog)
- Double Wins for Soon-to-Be Newlyweds - Trail Runner Magazine (Blog)
- Elisabet Barnes, 2015 Marathon Des Sables Champion, Interview – iRunFar (Blog)
- 2010 Marathon des Sables Results and Commentary – iRunFar (Blog)
- Pre-2014 Marathon des Sables Interviews with Laurence Klein, Nikki Kimball & Julie Bryan – iRunFar (Blog)
- Ester Alves Pre-2015 Transvulcania Ultramarathon Interview – iRunFar (Blog)
- Pre-2014 Marathon des Sables Interviews With Mohamad Ahansal, Salameh Al Aqra & Danny Kendall – iRunFar (Blog)
Collection - Ultra-Pacing Mastery: 3-Week Challenge
Foundation & Feel
View workout details
- 5min @ 7'00''/km
- 50min @ 6'22''/km
- 5min @ 7'00''/km
Sustained Effort Simulation
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- 15min @ 6'15''/km
- 4 lots of:
- 8min @ 5'22''/km
- 3min rest
- 15min @ 6'15''/km
Active Recovery
View workout details
- 5min @ 6'45''/km
- 20min @ 6'45''/km
- 5min @ 6'45''/km
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