How do you pace an ultra race? I get asked this question by my coaching clients a lot. It’s both a really important and tricky question to answer succinctly. Ultimately, pacing an ultra well is difficult but I have four mantras I like to follow...

Why is pacing an ultra more difficult?

First the semi-obvious stuff. Ultramarathons are mostly not like road marathons, where you know that if you can dial into say a 6-min/mile pace and hold it, your time will be 2:37.

Ultras come in all shapes and sizes and bring a big bundle of variables:

  • The terrain (overall ascent and underfoot conditions can be a mixture of muddy, rocky, wet, snowy, sandy)
  • The weather (you don't have the benefit of being sheltered by skyscrapers, while things like wind, rain and sun have more impact)
  • Fueling and hydration (which become more important and more difficult to get right)
  • Mindset management (there will be motivational lulls, so trying to cling desperately to a predetermined pace could accelerate decline)
  • Greater fatigue (muscular, mental and other possible physical effects)
  • Running through the night (where reduced visibility and battling your circadian rhythms often brings a lull or two)

And there's the simple fact that being out of your feet for many more hours means there’s more chance for things to go wrong.

Although Spain’s Pau Capell averaged 11.5-min/miles (including aid station stops) in winning the 2019 Ultra-Trail du Mont-Blanc (105 miles, 30,000ft ascent), his pace varied from 6.4-min/miles on flats/downhills to 20.5-min/miles on uphills.

In a performance that's commonly seen as impressively strong and consistent, a set pace on his watch wouldn't have been much of a guide (though an average pace or speed could have been a helpful pointer after a few hours).

As a footnote, Capell ran to splits, but he'd done UTMB before and therefore had a good idea of what might be possible for him.

Splits can be useful as a guide if based on appropriate data, but they can easily be counterproductive if getting behind your estimated timings will affect you mindset negatively. I sometimes start a race with rough splits, but usually forget all about them (though record/FKT attempts are different).

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Can you use heart rate to pace your race?

What about heart rate (HR) as a gauge of pace? Temperature, caffeine, fueling, dehydration, cardiac drift and faulty tech/GPS reception affects the data. Plus, your heart has to work hard to climb a big lump, but doesn’t have to work hard on the descent, so your watch could say 180bpm one minute and 110bpm another, and you could be pacing it optimally.

In some scenarios, HR could be a semi-useful gauge to stop you overdoing things in the first few hours, but probably not for the entirety of the race. For me, perceived effort and running on feel seem to work best.

We want to stay below aerobic and lactate thresholds, otherwise waste products associated with fatigue increase in the bloodstream and muscles. The longer we can go without depleting glycogen stores (by staying in easier fat-metabolising zones), the more energy/power we will have later on. The problem is that while lactate threshold is easy to detect (legs getting increasingly heavy or 'full', especially on climbs), aerobic threshold isn't (some pointers below).

How to pace an ultra

Research from track-based ultras demonstrates what has become my pacing mantra #1: the people who have the best race are those who slow the least.

A 2004 study from the University of Cape Town investigating pacing at 100Ks in 1995 and 1997 found that everyone slowed somewhat, including the podium finishers. But the fastest runners only ran their last 10K loop 15 percent slower than their first, while the slower runners' pacing dropped off by 40 percent.

Fastest runners start at lower relative intensities and display a more even pacing strategy than slower runners.

A 2016 study of 24-hour racing (International Journal of Sports Physiology and Performance)

So we need to find the relative intensity, which suits us, on that day. But how? It does take some trial and error, and experience helps.

Two more mantras I like are:

#2. Your slowest pace is more important than your fastest pace.

It doesn't matter one jot if you clock some 5.5-min/miles early on, if you're doing 15-min/miles on similar terrain later in the race. In fact, it means you've cocked it up.

Broadly speaking, if you settle into 8-min/miles early on and are doing 10-min-miles on similar terrain many hours later, you'll likely have had a good race.

#3. Save yourself for a strong second half.

Strong almost never means faster, but instead saving something for later, rather than 'going hard and hanging on'. The second half of a race is when it really starts.

In fact, try not to race other people in the first half, as you're more likely to go at an unsuitable pace for you. The 2016 study mentioned above found "'herd behaviour' seems to interfere with pacing strategy”. But by all means, race people in the second half, which can add motivation and make you feel you're doing well.

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Be the fastest tortoise...

Like most runners, I've gone out too hard and blown up. It's great fun. For a bit. Then, as people pass you for the next few hours, you feel a bit stupid. Over time I've learnt to race more patiently, with discipline, to be the tortoise, which has paid off at UTMB and other Ultra-Trail World Tour races.

The 'fastest tortoise' approach also worked at the 2016 53-mile Highland Fling, which doubled as the British Athletics Ultra Trail Championships and GB trial.

“Typically [with the exception of a few 'super-humans' like Capell, Jim Walmsley and Kilian Jornet] in competitive ultra races, the person leading at halfway doesn’t end up being the winner," said my coach at the time, 100-mile ace Ian Sharman.

"For the first half of the race, ignore what position you are in. Don't chase people and positions early on. Ask yourself, are you breathing harder than average? Are you breathing harder than those around you? You should be thinking, does my effort feel right?

"From halfway, you can start chasing down runners ahead, many of whom will have 'mis-paced' it and be slowing," added Ian. "If you’ve paced it right, it’ll feel like others are slowing, coming back to you.”

I followed Ian's advice, placed second and earned a GB vest.

It's not about being super-relaxed or lazy in the first half. It's just keeping things comfortable. It's going to get hard anyway, so why rush to that dark place?

I think of it as the three Cs; you should be calm, controlled and confident (that you're pacing it smarter than some of those ahead of you). My effort felt even throughout and those ahead of me slowed down. In retrospect, I realise I was concentrating on the process of racing well, rather than the outcome as such (I wasn't expecting to even place top-five).

It should be said that Donnie Campbell won that race after going out hard with the lead group, a la Capell. So there isn't just one way to race well. But that tactic has much less chance of being successful for most people.

"Don't be a d£ckhead"

Your mind and motivation are hugely important in all of this, as are your pre-race expectations. If you're exceeding your goals, you'll likely be in a happy place and continue to excel. Moving past rival competitors in the second half is an exhilarating feeling and you'll find you can easily ignore your body's signals to slow down. But of course the opposite is often true, too.

For motivation and smart pacing, the brain needs to be well fueled and the 3 Levers Approach is crucial – they're all linked. Both anecdotally and in several studies of marathon pacing, women are much better at pacing than men. Probably, at risk of stereotyping, because they tend to have less ego.

But if you remember nothing else from this, make it my mantra #4: Don’t be a d£ckhead in the first half. Don’t be a wimp in the second.

Damian Hall is a record-breaking ultra runner, coach and author of In It For The Long Run (Vertebrate Publishing)