Why Marathon Pace Is So Important

Running the right pace in a marathon is critical to a successful finish.   

But so many people get marathon pacing all wrong – they don’t have a plan, they go out too fast and they crash and burn.   Here, I unfold the reasons why your marathon pace is so important, and figure out how to determine it.

Why Do We Need To Worry About Pace?

Pacing is the idea of introducing controlled moderation to your race.

Almost every physical activity, sport, and pursuit require bursts of energy, tempered with intervals of decreased exertion.  Think about surfing as a good example – there is the moderate exertion of paddling, the rest period of waiting for a wave, then the burst of energy required to catch a wave and ride it.   Tennis has a rhythm – a flow of momentum that surges and flows, with breaks every time the ball goes out of play.   Gym work is basically intense periods of exertion, broken up by rest breaks.

Then comes endurance sports such as cycling, swimming, and distance running.   This blog is all about running marathons, so let’s hone in on distance running.   Distance running isn’t like normal activities that have a wax and wane of energy exertion.   No, distance running is all about applied, continual exertion.   I’ve illustrated how this might look below:

Exertion Graph

Now no marathon is a perfectly straight line of exertion.   Chances are you get buoyed along at the start line for a while, and near the end, you might have to dig in a little deeper.  Any gradients or changes in terrain might affect your exertion levels too.   But the whole principle here is different to what we’re used to seeing in other activities.

The problem is, many marathoners – especially first-timers – don’t quite wrap their heads around this concept well enough before they line up at the start line.   They haven’t really thought about how they are going to be able to maintain that constant level of exertion over three, four or five hours.

Related: Running Pace Calculator | Calculate Pace, Distance, & Time

An Epidemic of Overambitious Achievers

First, let me show you another nice graph:


Average Marathon Pace Graph
Average running speeds over the course of a marathon (source: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0057602)

This study measured the average running speed for a group of marathon runners over their event.  So we can consider the above graph to be the speed profile of the average marathon runner (Mister Average Marathoner, or Mr. A, let’s call him).

Meet Mister A
Mister A, shortly before starting his marathon

Notice how on the graph above, Mister A starts off well – he’s running at just under 3.5 metres per second – that’s around 12.6 kilometres per hour for pretty much the first half of the race.   That’s a good speed.   In fact, if he can keep that up, he’ll finish the marathon in around 3hrs and 20 minutes.  That’s an awesome time!

But then something funny happens around the halfway point.   Mister A begins to slow down.   In fact, his pace continues to drop off – he’s struggling to maintain a 2.8 m/s pace.   That’s a 20 percent reduction in pace he has experienced.  Things aren’t looking so hot for Mister A – he has to stop and walk for short spells.   He manages to pick up the pace slightly when the finish line is in sight, but only briefly.

Mister A Finish Line
Mister A, shortly after completing his marathon

How does Mister A look at the finish line?  He’s burnt out.   He’s had to push through constant pain and discomfort for the second half of his race, and boy does he feel it.

If you go and stand at the finish line of a marathon, you’ll see a lot of people that look like mister A – remember, he represents the average results of a group of marathon runners.

So, what went wrong?  Well, we could start to look at Mister A’s physiology and so on, but really his poor second-half marathon performance can be attributed to two root causes:

  1. Mister A didn’t train enough, or
  2. Mister A didn’t pace himself correctly.

Often it is a combination of the two.   But today, I’m talking strictly about pace.  Mister A is – like me and many other marathoners – a pretty ambitious guy.   He likes achievement, sometimes so much that he pursues it even if it means a crappy second half of a marathon.  The day before his race, he might have overheard his office rival mention how he had run a 4:05 marathon, so Mister A decided to change his strategy at the last minute to try and thrash him.   Or maybe when Mister A lined up at the start line, he felt a surge of energy and just thought – hey, let’s see how fast I can blow through this thing.

At the end of the day, Mister A forgot that distance running requires a constant, controlled exertion of energy across the duration of the whole run.

He hadn’t prepared sufficiently to know what speed he was capable of running an entire marathon, so he took a gamble and went out fast.   He treated marathon running like any other sport, where you have to perform in a burst of energy with breaks.

But in a marathon, there are no real breaks.   You can pause at an aid station to pick up some water and walk for a minute, but really the point of a marathon is to run the whole damn thing.   That was certainly Mister A’s intention. He just pushed himself too hard too early – so ended up suffering.

Pace = King

So, we’ve established that going out too fast can lead you to crash and burn like Mister A.   (Alright, he managed to finish his marathon, but it was barely a graceful effort.)   How do we avoid this when we come to run our own marathons?

Meet Mister P.

Meet Mister P
Mister P, shortly before starting the marathon

Mister P is similar to Mister A in many ways.   They’ve both got the same level of running fitness, as it happens.   They also look pretty similar, although Mister P has some hair.   One more thing – Mister P is wearing a GPS watch.


This is because Mister P understands how important pace is during a marathon.  Mister P has got a target finish time in mind, a bit like Mister A.  But Mister P’s finishing time is more realistic than Mister A’s.   Mister P has been training towards this finishing time for the past four months, and he knows exactly the speed he’ll have to run throughout the marathon to achieve it.

Mister P’s aim is to run a constant speed throughout the whole marathon.

A constant speed follows the logic that a marathon requires a continuous level of sustained exertion.   It means finishing the marathon at the same speed that you started.   This isn’t that crazy – you might have heard how elite marathon runners actually speed up throughout their race.   While this is a great achievement if you can do it, most of us don’t have the hours of training and running experience the pro’s do.   So instead, we should aim for a constant pace – like Mister P.

What Happens During a Marathon?

Mister A and Mister P started their marathon together.   Mister A soon disappeared ahead, feeling the surge of energy and adrenaline from finally being able to get started.   He excitedly got swept along in a group of fast runners.   Mister P, on the other hand, started off and quickly checked his pace to make sure he was running at the speed he wanted to be.   A lot of people overtook Mister P during the first half of the race.

First Half of the Marathon
The First Half of the Marathon

But then, right around the half-way point, things start to change.   Mister A begins to feel…overexerted?   Uncomfortable?  He decides to dial it back a bit.   He continues onwards for some time, then eventually he hears footsteps behind him.   It’s Mister P, progressing steadily at the same pace at which he started, more than two hours earlier.  Mister P is continuously checking his GPS watch to check that he’s going at his planned speed.  Mister A sees Mister P running strong and tries to emulate him, but his body refuses.   He has to jog/walk for the rest of the race.

Second Half of the Marathon
The Second Half of the Marathon

What Pace Should I Run?

Great question.   How does Mister P know what pace he can sustain for an entire marathon?  How do you determine this?  Well, obviously, experience helps.  The longer you’ve been running, the more you are familiar with what pace you can sustain.

There is a big selection of online pace calculators.   Some of them use your half marathon time to compute a suitable marathon pace.

Pace Graph Revisited

In the case of Mister P, he had completed a half marathon in 2hrs, four months before his marathon.   So, he recognized that he could run this pace, he just needed to build up the distance.   Then he spent the next three months running progressively longer and longer runs on weekends, maxing out at 21 miles.   Throughout the week he ran two shorter runs at his 4hr marathon pace and did one speed work session.   In other words, he plotted a course and stuck to his training plan.

If you’re still uncertain which pace to aim for, try your best to take your ego out of the equation.   Try and make a decision based on you being able to comfortably finish a marathon without stopping running.  Don’t fret too much about getting a ‘good’ finishing time – especially if you’re preparing for your first marathon.   Aim for a time and pace that is reflective of the training you’ve put in, and stick to it!

Why Marathon Pace Is So Important 1


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Thomas Watson is an ultra-runner, UESCA-certified running coach, and the founder of MarathonHandbook.com. His work has been featured in Runner's World, Livestrong.com, MapMyRun, and many other running publications. He likes running interesting races and playing with his two tiny kids. More at his bio.

2 thoughts on “Why Marathon Pace Is So Important”

  1. With just one marathon behind me, I’m hardly an expert, but I did follow the advice of not getting carried away at the start. That was tough. It felt like I was hardly moving, and with a large half marathon field running with the marathon for the first 10k, it was even tougher – but I stuck with it and it definitely paid off.

    In your 4 hour marathon book you mention the mental boost from passing people who had run out of steam. I can’t echo that strongly enough. I know that the sense of achievement I got as I started passing people around mile 18 was huge and it carried me to the end.

    You can see from the data below that plenty of others were like your Mr A. I ran a consistent 6 min/km pace for a 4hr 15m finish at a small marathon (Leicester). Just 472 male runners (I don’t have the female data). Here is my position at the recorded splits

    6 mile – 406
    19 mile – 343
    26.1 mile – 286

    I know I wasn’t quick, but I crossed that line exhausted and I hadn’t walked a single step, so clearly on that day, I found my pace. Overtaking 40% of the other men was a huge confidence boost, just when it’s needed.

    Next time I will be sub 4 hours! 🙂


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