How I Ran a Sub-3 Hour Marathon: the Half:3x5 Pacing Strategy

The key to success in any endurance race is pacing. Period.

Overconfidence is probably the biggest "killer" of race goals.

The classic mistake

Here's a potentially familiar story: you're running the marathon. You set off from the start line. You've tapered for a few weeks, your glycogen levels are stocked up and once the race starts, you feel fucking amazing.

So what do you do? If you don't know any better, you naturally kick it up a gear and go harder than you planned. After all, you feel like you can run like this forever, so why not?

You run 10, 20, maybe 30 seconds faster per mile. Your discipline with gels loosens. You even high-five a few spectators. Fuck it — you’re flying.

What you don’t realise is that your effort has started creeping above a line — a physiological threshold — that determines how long you can hold this pace. It’s called your lactate threshold.

Then, somewhere after 10 miles, the reality hits. Suddenly, you're hit by a wave of fatigue. Your legs don't want to maintain the pace that, just a few miles earlier, you were floating along at.

Your body can't give anymore. From here on out, it’s survival mode.

The importance of pacing

Sound familiar? This is an experience that is often learnt the hard way in racing - and it took me a few attempts to learn that lesson.

Sure, some of us can trust our bodies on the day. We feel good, we push harder, and it pays off. But these experiences are far from the norm. Most people feel good, push harder... and then fall off a cliff.

The common cause is, in my view, simple: lactate.

When you run, your body is constantly producing a molecule called lactate. Usually, your body clears away this molecule just fine.

But once you start running beyond your lactate threshold, you start producing it faster than you can clear it.

And when you have too much lactate, you begin to rapidly fatigue. Your muscles begin to rapidly tire. That's why you can only hold that intensity for around an hour.

But nobody runs a marathon in under an hour. Not even close. Which is why, to race well in the marathon, you have to stay under that threshold — at least until it’s time to kick.

That's the problem when you run 10-30 seconds or whatever faster than you planned. Somewhere in boundaries of those seconds could be your lactate threshold, and thus as you run the early stages of the race faster than planned, you're rapidly killing off your energy.

Therefore your goal should be to figure out what your lactate threshold is, and run the majority of the marathon below it.

Then, as the finish line draws nearer, you can begin to pick up the pace, generally peaking above your lactate threshold for the last 10K or so.

This is why they often say that the marathon begins at the 10K mark.

This pacing strategy — running slower at the start, then gradually picking up the pace — is called negative splits.

There are numerous ways to pull off negative splits. You could split it down the middle: run the first half easy, the second harder. You could hold off until the last 10K, then go all-out. Or, you can follow the half:3x5 strategy.

The Half:3x5 Pacing Strategy — Four Phases

This approach isn't as simple as "first half easy, second half hard," but it's more nuanced and a lot more fun.

A personal challenge I face in the marathon is the daunting prospect of 26 miles at the same pace. The idea of chunking the marathon into phases really scratches something deep inside of me.

The strategy is broken down into 4 phases:

• First Half (13.1 miles): Cruise. Stay relaxed and below your lactate threshold. Let others pass you.

• Next 5 miles: Slight pick-up — maybe 10–20 seconds faster per mile.

• Next 5 miles: Edge up again. You’re flirting with your lactate threshold now.

• Final 5K: All out. This is what you saved it for.

The key to this whole strategy is holding back. If you don't trust the system and refrain from picking up the pace and burning your matches, it will not work.

With this approach, think of the first half as a warmup. It's a doddle. It shouldn't be easy per se, but it shouldn't be taxing, either. It should feel very comfortably hard.

You're conserving your energy for the real race coming later.

It's the second half where the real work begins. You pick up the pace slightly for the next five miles. You're still below your lactate threshold, but you're beginning to work.

The challenge starts in the next five miles. At this stage, you're 18 miles into the race. The prospect of picking up pace at this stage may feel daunting to many, but if you've followed the advice and held back, you'll be fine - I promise.

At this stage, you will quite literally begin to feel your lactate threshold. You need to fine-tune your pace by mere seconds to make sure that you're still running on or right below it. Find the point where you can feel yourself fatiguing exponentially more, and then reduce the pace by a few seconds per mile.

It'll be hard but hold that pace until mile 23.

This is where the fun begins. You're in the last 5K. Your legs are tired, but you have something left in the tank. You have enough left to blast through these last 3 miles. You can give it everything you have and leave nothing behind.

Well done.

An example of Half:3x5 in practise.

Let’s say you’re targeting 6:30/mi for your marathon. Here's what your pacing could look like

• First half: ~6:35–6:30/mi

• Next 5: drop to ~6:25/mi

• Next 5: 6:20–6:15 (depending on your threshold)

• Final 5K: whatever you've got left — 6:00–6:10, or faster

There is no hard and fast rules for the timings, as long as it all adds up to your target time.

Obviously this particular approach assumes a certain degree of fitness. But you should be at a certain level of fitness if you're aiming for a sub-3 marathon. It is hard.

That being said, this approach can be used whether you're aiming for a 2:30 marathon or a 5 hour marathon. The principles remain the same.

But will it work?

I've used this strategy twice: once at the Amazing Thailand Bangkok Marathon 2024 where I got my first sub-3. Then I used it again this May at Leiden Marathon, where I managed a 2:44.

It works. But we're all different. What works for some, may not work for others. There is no one-size-fits-all in running.

The key takeaway from this post, whether or not you follow the exact strategy, is that you need to hold yourself back. Follow your plan, restrain yourself, and I have no doubt that you will smash it on the day.