Marathon Training - The Science
There are no short cuts (well there are but you might not enjoy the whole experience quite so much!)
I think a key bit of advice I was given was that when you start your 16 week block of marathon training you’re not meant to be 3 weeks away from being ready for your marathon. Marathon training is hard but so rewarding; it’s a journey of steps and setbacks, a bit like a game of snakes and ladders, sometimes it’s down to the roll of the dice of what you can control and what you can’t.
I like to control as many controllables as I can and start with training the body to be as effecient as possible because successful marathon running depends on how efficiently your body can use oxygen, how resistant you are to fatigue, and how well you can hold a steady pace. If you run too fast, train too hard, or skip the basics, and you’ll pay for it on race day; and 4 months is a lot of time to throw away.
The Science
The marathon is overwhelmingly an aerobic event with over 97% of your energy coming from your aerobic system, which just means with oxygen, so running comfortably. The issues, setbacks and blow ups, in my experience, always stem from training and racing at a pace that is too fast for your body to handle, the pace dips into the anaerobic zone, (without oxygen system) before it’s ready (26.2 miles is a long way) and whilst the anaerobic system is powerful it’s limited. If you push it too much, you’ll accumulate fatigue, damage your running economy, and increase your risk of not making the start line at all.
Training slower, with more controlled miles is not weakness but a necessity; it’s the most effective way to build your engine that you’ll need on race day.
Running Economy and Fatigue
Running economy is how efficiently your body uses oxygen at a given pace so the better your economy, the less energy it takes to run each mile.
But tere’s the catch: if you spend too much time in training running too fast, you accumulate fatigue, break down your form, and harm your running economy - each mile will feel like running through treacle.
Slower training builds efficiency because it strengthens slow-twitch muscle fibres, conditions your cardiovascular system, and teaches your body to burn fuel more effectively.
Lactate Threshold Matters for Marathon Runners
What is Lactate Threshold?
When you run, your body produces lactate as a by-product of burning fuel. At easy paces, your body can clear lactate quickly and keep everything in balance.
But as you speed up, there’s a tipping point where lactate builds up faster than your body can clear it. That tipping point is your lactate threshold.
The higher your lactate threshold, the faster you can run before fatigue sets in. For marathon runners, this means being able to hold goal pace for longer without “blowing up.”
How to improve your lactate threshold
You don’t need fancy lab tests to improve your lactate threshold, being a consistent runner does the job.
1. Long Runs (easy pace)
Builds your aerobic base.
Teaches your body to use oxygen and fat efficiently.
Foundations for everything else.
2. Tempo Runs (comfortably hard pace)
Run for 20–40 minutes at a pace you can only speak in 3–4-word phrases.
This is just below or around threshold.
Teaches your body to tolerate and clear lactate better.
3. Interval Sessions
Example: 6 × 5 minutes at 10k–half marathon pace, 2–3 min slow run recovery.
Pushes you above threshold in short, controlled bursts.
4. Consistency
Improvements come from weeks and months of regular training, not one hard session.
When marathon training, building a higher lactate threshold means you’ll be able to run faster, for longer, with less fatigue. The best way to improve it isn’t endless speedwork, it’s a smart mix of long runs, tempo efforts, and consistent training at the right intensity.
Build your base, sprinkle in threshold work, and you’ll see the difference come race day.
The 4:1 Rule
Here’s one of the simplest but most powerful pacing rules in marathons:
For every 1 second per mile, you run too fast in the first 10k, you’ll lose around 4 seconds per mile in the final 10k.
Example: goal pace = 10:00/mi. If you run at 9:45/mi in the first 10k, you’re 15 seconds too fast. By the final miles, you’ll likely be slogging at 11:00/mi.
Why? Because glycogen drains quicker, lactate accumulates, and your form and economy collapse.
In other words, you cannot “bank” time in a marathon. You can only borrow and trust me; you’ll pay it back with interest.
The science is clear
Train slower to run stronger: easy miles build economy and durability.
Raise your lactate threshold: tempo runs and intervals give you more room to work at marathon pace.
Respect the 4:1 rule: go out too fast and the marathon will humble you in the final miles.