Why Pacing Mistakes Become Catastrophic in Ultramarathons
Last Update eptember 2nd, 2026 by Etienne Durocher
One of the most fascinating aspects of ultramarathon racing is how small mistakes become large consequences.
A marathon runner can sometimes recover from an aggressive opening few kilometres. A strong athlete may absorb the mistake, settle into a sustainable rhythm, and still salvage a respectable performance.
Ultramarathons rarely offer the same forgiveness.
A pacing mistake made during the first hour of a 100-kilometre race may still be affecting the athlete eight, ten, or even fifteen hours later. What initially feels insignificant gradually compounds. Energy expenditure increases. Fueling becomes more difficult. Muscular fatigue accumulates more rapidly. Decision-making deteriorates.
Eventually, the athlete experiences what appears to be a sudden collapse.
The reality is usually different.
The collapse often began many hours earlier.
Learn how this fits into a complete running strategy: Why Slowing Down Early Is the Fastest Way to Finish an Ultramarathon
This is one of the reasons experienced ultrarunners frequently appear conservative during the opening stages of races. To an observer, they may look almost too relaxed. They may walk climbs that seem runnable. They may allow other competitors to move ahead. They may appear to be racing cautiously.
In reality, they are often racing intelligently.
They understand something that many newer ultrarunners eventually learn through experience.
The race you are running now is often determined by decisions you made hours ago.
What Makes Ultramarathons Different
Many pacing principles apply across all race distances.
Start conservatively. Respect the conditions. Manage effort intelligently. Fuel consistently.
These fundamentals remain true whether the athlete is racing a 10K, marathon, or ultramarathon.
The difference is that ultramarathons dramatically increase the consequences of getting those fundamentals wrong.
In a marathon, the body may be exposed to race stress for three, four, or five hours.
In a 100-mile race, that exposure may last twenty, twenty-five, or even thirty hours.
The margin for error becomes much smaller.
Every unnecessary acceleration creates a cost.
Every overly aggressive climb creates a cost.
Every decision to ignore early warning signs creates a cost.
Initially, those costs seem manageable.
The athlete feels strong. The body feels fresh. The pace appears sustainable.
Unfortunately, ultramarathons reward long-term thinking rather than short-term impressions.
The body keeps track of everything. Eventually, it asks for payment.
Why Early Success Can Be Dangerous
One of the biggest traps in ultramarathon racing is feeling too good early.
This sounds counterintuitive.
Most runners spend months hoping to feel strong on race day. They want confidence. They want energy. They want the sensation that training has prepared them properly.
The problem is that feeling strong during the opening stages of an ultramarathon often creates temptation.
The athlete begins passing competitors.
The pace feels comfortable.
The climbs seem manageable.
The race unfolds exactly as hoped.
At this stage, many runners begin making decisions based on how they feel now rather than how they need to feel later.
This is where pacing errors frequently begin.
The body is still operating with fresh legs, full glycogen stores, and minimal fatigue. The athlete interprets this temporary state as evidence that a faster pace is sustainable.
Several hours later, reality begins catching up.
The issue is not that the athlete lacked fitness.
The issue is that they confused current comfort with future sustainability.
Experienced ultrarunners learn that these are not the same thing.
The Compounding Effect of Small Mistakes
One reason pacing mistakes become so destructive in ultramarathons is that they rarely exist in isolation.
A slightly aggressive pace increases energy expenditure.
Increased energy expenditure often increases fueling demands.
Higher fueling demands can create digestive stress.
Digestive stress may reduce calorie intake.
Reduced calorie intake can contribute to declining energy.
Declining energy influences decision-making.
Poor decisions often create additional pacing errors.
The cycle continues.
This compounding effect is what makes ultramarathons so fascinating and so challenging. The athlete is rarely dealing with a single problem. Instead, they are managing a network of interconnected variables.
Pacing influences nutrition.
Nutrition influences energy.
Energy influences decision-making.
Decision-making influences pacing.
Everything is connected.
This is why successful ultrarunners frequently appear almost obsessed with patience. They understand that preventing problems is usually easier than solving them later.
This topic works alongside: Trail Running Technique
Why Ego Is Often the Real Enemy
Many pacing mistakes originate from a source that has little to do with fitness.
They originate from ego.
The word ego is sometimes misunderstood. It does not necessarily refer to arrogance. More often, it refers to the desire to prove something.
Insight
They struggle because their footwear is not aligned with their workload.
Guide Here
The athlete wants to prove they belong.
They want to prove they are fit.
They want to prove they can keep up with stronger competitors.
They want to prove that training has worked.
Unfortunately, ultramarathons do not reward proof.
They reward patience.
The athlete who races according to ego often spends energy unnecessarily. They respond emotionally rather than strategically. They become attached to competitors, positions, or pacing targets that have little relevance to the actual demands of the race.
The athlete who races according to the conditions generally performs better.
They focus on execution.
They focus on sustainability.
They focus on making good decisions repeatedly.
Over long distances, this mindset becomes an enormous advantage.
One of the best ways to improve ultramarathon pacing is learning to trust effort rather than pace alone. If you haven't already read it, Effort-Based Running vs Pace-Based Running explores why the body's feedback often becomes more valuable than the numbers on your watch.
What Spartathlon Reinforced
Spartathlon reinforced perhaps the most important pacing lesson I have ever learned.
The race does not care how strong you feel during the first fifty kilometres.
It cares how well you manage yourself over the next two hundred.
This reality changes how athletes approach the event.
The objective is not to maximize performance early.
The objective is to preserve performance for later.
During races of this duration, the temptation to run slightly faster appears constantly. The pace feels easy. The legs feel strong. Other athletes are moving confidently. Every instinct encourages aggression.
The successful athletes learn to resist that temptation.
They understand that the race has not truly started yet.
This mindset can feel uncomfortable, especially for competitive runners. However, it often becomes one of the defining characteristics of successful ultramarathon execution.
Patience becomes a performance skill.
What Blagoy's Spartathlon Experience Reinforced
One of the most valuable lessons from Blagoy's Spartathlon experience involved the relationship between pacing and accumulated consequences.
The challenge was never one single decision.
The challenge was the combined effect of multiple decisions.
Slightly faster pacing created additional demands. Those demands increased fatigue. Increased fatigue made subsequent decisions more difficult. Eventually, the athlete found themselves managing challenges that had been quietly building for hours.
This pattern appears repeatedly in ultramarathons.
The athlete rarely fails because of one catastrophic moment.
More often, the race gradually becomes harder because small issues were allowed to accumulate.
This is why experienced ultrarunners focus so heavily on discipline.
Discipline interrupts the cycle before it begins.
What 24-Hour Racing Taught Me
Twenty-four-hour racing offers a particularly brutal lesson about pacing.
You can rarely force a good outcome.
You can only create conditions that allow one to emerge.
Athletes who chase speed early often discover that the race becomes increasingly expensive. Every decision creates a future consequence. The body remains remarkably honest about this relationship.
What makes 24-hour racing unique is that there is nowhere to hide from those consequences. The event lasts long enough for nearly every mistake to become visible.
This experience reinforced a lesson that applies equally to 100K and 100-mile races.
The goal is not to maximize output.
The goal is to maximize sustainable output.
Those two concepts are very different.
The runners who understand the distinction usually perform significantly better.
Practical Tips for Runners
The first recommendation is to respect how long the race actually is. Many pacing mistakes occur because athletes unconsciously race the first few hours rather than the entire event.
Second, make pacing decisions based on sustainability rather than excitement. Feeling strong early should increase confidence, not aggression.
Third, remember that every pacing decision influences fueling, hydration, and recovery. Nothing exists in isolation during an ultramarathon.
Finally, focus on preserving options. A conservative athlete can always accelerate later. An exhausted athlete has very few solutions available.
To continue building your running knowledge, read: How to Pace Trail Races Without Destroying Your Legs Early
A Coach's Perspective
One of the most common observations I make while coaching ultramarathon athletes is that fitness is rarely the primary limitation.
Execution is.
Many athletes arrive at race day physically capable of achieving their goals. The challenge is maintaining the discipline required to express that fitness effectively over long periods.
This is where ultramarathons become fascinating.
The distances expose impatience.
They expose ego.
They expose poor decision-making.
At the same time, they reward humility, patience, and adaptability.
The runners who consistently succeed are usually not the athletes trying to prove how strong they are.
They are the athletes quietly protecting their ability to remain strong later.
Final Thoughts
Pacing mistakes become catastrophic in ultramarathons because the distances amplify consequences.
A small error during the opening stages may not feel significant at the time. However, over ten, fifteen, or twenty hours, that error can influence every aspect of the race. Energy management, fueling, hydration, decision-making, and mental resilience all become connected.
This is why experienced ultrarunners place such a high value on patience.
They understand that races are rarely won early.
They are often lost there.
If there is one lesson to take from this article, it is this:
The greatest pacing skill in ultramarathons is not knowing when to push.
It is knowing when not to.
The athletes who master that lesson frequently discover that their strongest performances occur not because they ran harder than everyone else, but because they remained patient longer.
