Mastering Ultra‑Marathon Pacing: Lessons from the World's Toughest Races
The moment the desert sun slipped over the dunes
I still hear the low‑hum of the wind‑blown sand as I laced up for the first stage of a seven‑day desert race. The horizon was a wavering line of heat‑shimmer, the kind of place that makes you question whether you’ll ever finish the day’s 30 km. I started at a pace that felt aggressive – the kind of “let’s hit the front” instinct many of us have when the start gun cracks. By kilometre 8, the sand had turned into a thick, exhausting carpet and my heart was pounding faster than the rhythm of my feet. I slowed, then stopped, and for a long, hot stretch I simply listened.
That uneasy pause was the first real lesson in pacing: speed is a tool, not a rule. The desert, the mountain, the heat – they all have a voice, and if you’re not hearing it, you’ll pay for it later.
Why pacing matters more than you think
The science of effort
Physiologically, the body has a limited “glycogen budget” for high‑intensity work. When you run above your Lactate Threshold (often called tempo pace), you burn glycogen faster than you can replenish it, leading to early fatigue and, in extreme environments, a higher risk of heat‑related decline. Studies on marathon and ultra‑marathon runners show that a steady‑state pace – roughly 70‑80 % of maximal aerobic capacity – maximises fat oxidation, spares glycogen and improves thermoregulation.
The mental side‑effect
Pacing isn’t just a number on a watch; it’s a mental framework. When you set a realistic zone, you give yourself a permission slip* to stay calm, to focus on form, and to enjoy the scenery rather than obsess over the clock. This mental breathing room is what elite ultrarunners call “running your own race”.
Turning the concept into a personal coaching plan
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Identify your personalised pace zones – start with a recent long run (15‑20 km) and note the average heart‑rate and perceived effort. Split the data into three zones:
- Easy (Recovery) – 0.8 %–0.9 % of max HR – perfect for warm‑ups, cool‑downs and long steady miles.
- Tempo (Lactate Threshold) – 0.9 %–1.0 % of max HR – the sweet spot for 10‑20 km runs that build stamina.
- Hard (Race‑pace) – 1.0 %–1.1 % of max HR – short intervals, hill repeats, or the final push on a race day.
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Build adaptive training weeks – let the first week be a “baseline” (70 % of your usual mileage). The following week, increase the long run by 10 % while keeping the easy runs at the same duration. The third week, add a tempo segment (20 % of the long run) at the upper edge of your threshold zone. This pattern lets you auto‑adjust based on how you feel, mirroring the way a seasoned runner will back‑off when the heat spikes.
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Create custom workouts that reflect real‑race terrain – if you know a race has a long, flat desert stage, design a 30 km steady‑state run at the easy‑to‑tempo boundary. If the course includes steep climbs, schedule hill repeats that sit in the hard zone for 2‑3 minutes, then jog down for recovery.
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Use real‑time feedback to stay inside your zones – a simple chest‑strap or wrist monitor that shows heart‑rate and pace can alert you the moment you drift into the hard zone unintentionally. A gentle vibration or a colour‑coded display (green = easy, amber = tempo, red = hard) is enough to keep you honest without breaking your flow.
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Leverage collections and community insights – many runners share their favourite “pace‑zone workouts” in online groups. Borrow a proven 12‑kilometre tempo set, tweak the intervals to match your own zones, and log the result. Seeing how others have progressed can inspire you to fine‑tune your own plan.
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 | 0.85 % (Easy) | Warm‑up, relaxed, focus on breathing. |
| 2 | 4 km | 0.95 % (Tempo) | Hold a steady, comfortable effort – you should be able to speak in short sentences. |
| 3 | 2 km | 1.00 % (Hard) | Pick up the pace just enough to feel the legs working harder; think of a short race‑finish surge. |
| 4 | 4 km | 0.85 % (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.
When you finish, you’ll have experienced the three core zones in a single session, mirroring the way a race will demand you shift gears without losing control. Over the next weeks, extend the tempo portion, add hill repeats, or swap the flat for a sand‑track, depending on your upcoming target event.
Takeaway
Pacing isn’t a secret reserved for elite athletes; it’s a skill you can self‑coach with a little data, a clear zone structure and the habit of checking in with your body in real time. By treating each run as a miniature version of a race – with its own easy, tempo and hard sections – you’ll arrive at the start line feeling confident, resilient and ready to let the desert, the mountains, or the forest trail be your guide rather than a surprise opponent.
Happy running – and if you want to try this today, here’s the 12 km Progressive Pace Run to get you started.
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
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- 5min @ 6'45''/km
- 20min @ 6'45''/km
- 5min @ 6'45''/km
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