Why Zone 2 Running Works So Well

In this post, I’m going to explain the reasons why Zone 2 training works so well.

Trying to run in Zone 2 can be really frustrating. As a beginner runner, it can feel almost impossible, and as an intermediate, you feel like you have to run ridiculously slowly.

But if you stick with it, Zone 2 training can transform your running fitness. In an 8-week block of Zone 2 focused training, I shaved more than a minute off my 5k time.

In this post I’m going to give you three reasons why you implement Zone 2 training, and why all the struggles and frustrations are worth it:

• It allows you to increase mileage sustainably.
• It allows you to nail your faster-paced interval and tempo workouts.
• And of course, it builds your aerobic base (I’m going to explain why that’s important).

Let’s dive in.

1. It Allows You To Increase Training Volume

One of the biggest predictors of fitness and race performance is your average weekly volume leading up to the race.

Most runners face is that when training for a race or event that both mileage and intensity increase at the same time, which causes a double-whammy effect.

You accumulate more impact forces per week through the increased mileage, and at the same time, you’re increasing the average impact per stride by running more miles at a faster pace each week. It can end up being more than you can recover from. And more often than not (especially in my experience), leads to injury.

The solution to this problem lies in doing more Zone 2 running.

Because Zone 2 running is relatively low intensity, the impact forces are lessened, and therefore, you accumulate less fatigue throughout the week. This ultimately means you can train at a higher volume with lower injury risk.

It allowed me to consistently run 5 days a week and steadily increase my weekly mileage up to 60km without any sign of overtraining.

If you want to increase your weekly running volume — use Zone 2 training to do it. Add intensity later.

2. You Can Run Your Intervals And Tempos Harder

These are the most important workouts of the week.

You can recover from Zone 2 runs quicker than other, faster-paced runs, which means that you accumulate less fatigue over the week. This allows you to go into your weekly hard run feeling fresh and ready to attack it.

You’ll be more likely to hit or exceed your goal paces, so you’ll get more out of the session. I don’t think there was a single threshold or speed workout over that 8-week period where I failed to hit my intended splits.

That little extra bit of performance you can get out of your workouts will compound and lead to big increases in your fitness over time.

3. Builds Your Aerobic Base

Of course, it goes without saying that Zone 2 running will build your aerobic base:

• It improves your mitochondrial density and function, making your body more efficient at producing energy.
• It builds your capillary density, improving the blood flow to your muscles.
• It increases the size and changes the shape of your heart, allowing more blood to be pumped around your body per beat.

But what actually is your aerobic base, and why does it matter?

Peter Attia talks about fitness in terms of a pyramid. You have your aerobic base at the bottom and VO2 max at the top.

If you were trying to build the tallest pyramid in the shortest time, you wouldn’t spend much time building the foundations. Instead, you’d focus on stacking bricks on top of each other to make it as tall as possible. The way you’d do this by performing as many high-intensity workouts as you could (tempo, threshold, interval, and VO2 max sessions).

If you kept adding more and more bricks, eventually, it’d reach a point where it’d either topple over (an injury or illness), or you’d reach a point where you can’t make it any higher–adding any more bricks make the pyramid unstable (you plateau or pick up niggles).

Side note: This is a viable option for building maximum fitness in a limited time, and it’s how many race training programmes work. It can work well for cycling, but it’s a risky approach for higher-impact sports like running.

But if you wanted to make the pyramid as tall as possible, with no time constraints, you’d invest nearly all your time at the beginning on building the foundations–an aerobic base.

Once you had a solid base, you could then build vertically by adding more tempo, threshold and interval workouts. If, at any point, trying to make the pyramid any taller makes it unstable, you’d go back and put more time into building the base before building up again.

In short, the size of your aerobic base limits how fit you can get. And Zone 2 running is how you build that base.

Zone 2 running has worked wonders for me over the past 12 months. It allowed me to run a 3:32 marathon on my first attempt, and I’m going to make it a big part of my training as I train for a sub-3 attempt. I hope it works just as well for you!