The Tortoise and the Hare: The Science of Training Slow

Well, a hare that won the race anyway. As runners, we’re always seeking those slight changes to our routine that will help us get massive results. I’m constantly searching the internet, reading, and listening to podcasts to learn how to run more efficiently.

Most people just want a quick solution. They don’t want to wait for the results to come years later. They’re our gains, and we want them now!

Yet, we’ve all met people who rave about this one change that helped them immensely.

“I added yoga, and I’ve run injury-free ever since.”

“Cross-training three times a week. Add in some different workouts, and watch your fitness take off!”

“Snake oil. Two drops, and I’m running like Usain Bolt.” Or was that a post on Facebook about increasing your libido?

Either way, the answer is there isn’t one change that will lead to ultra-gains. As I’ve mentioned in prior posts, the most important thing is to be consistent. If you don’t run consistently, nothing else you do will matter.

But, if there were just one change I’d recommend, it’s simple: slow down.

👉 Want an alternative to using TrainingPeaks to track your workouts?: 5 Best TrainingPeaks Alternatives for Your Workouts

How Slowing Down Helps You Speed Up

I’ve talked so much about the Science of Ultra podcast that anyone who consistently reads my posts will probably exit this article after this sentence.

However, the episodes Mileage Matters Most, and Training Intensity Distribution are two of the best listens on increasing running performance.

It boils down to three simple things:

  1. Spend most of your running—around 80%—at an easy pace (about 65-80% of maximum heart rate)
  2. Slowly increase mileage by adding distance to some or all of your runs
  3. Be consistent

If most runners follow these three things, you’ll see long-term improvement gains. The keyword is “long-term.” There is no quick formula for endurance success. It’s hard work and time.

So with that said, let’s look at the specifics.

Most Top Runners Schedule a Lot of Slow Time

This is a simple fact. Most top runners you see taking the podium schedule a lot of slower, low-intensity training into their plans.

Even if the pros are running insane speeds, the effort is less intense, saving their legs for another day. I’ll dive into this more in the next section. Let’s first look at what the research shows.

A study from 2011 titled Distribution of Training Volume and Intensity of Elite Male and Female Track and Marathon Runners—a mouthful, to say the least—analyzed six of the best long-distance runners in Norway.

The study was an even split of males and females. Of these six individuals, three were international-level long-distance runners, and the other three were marathon runners.

The study found the runners spent the overwhelming majority (around 80% of weekly distance) at 65-82% of max heart rate (MHR). An individual with an MHR of 190 has a heart rate range of 124-156 bpm.

The rest of the training was dedicated to higher intensities, closer to 82-92% of MHR (156-175 bpm).

The reasons behind this are numerous, and someone more qualified could explain better, but I figure I can try to simplify it (I apologize to any scientists in advance).

Running more effortlessly allows the body to optimize the processes that help the muscles perform most efficiently. This comes in the form of:

  • Increased oxygen uptake in muscles
    • Your muscles need oxygen to break down glucose and convert it to adenosine triphosphate (ATP), which is used to power most processes in your cells
  • Increased lactate clearance
    • This expands your muscles’ ability to clear lactate and keep your muscles working efficiently (visit TrainingPeaks for a more detailed understanding)
  • Strengthens slow-twitch muscle fibers
    • These are critical for endurance athletes to keep you going for long distances

Similarly, the article What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? that appeared in the International Journal of Sports Physiology and Performance recommends the same training distribution. 80% at low intensity (zone two), with 20% spent at higher intensities.

Lastly, a review in 2017, The Effect of Periodization and Training Intensity Distribution on Middle- and Long-Distance Running Performance: A Systematic Review, and a later study done in 2020 by Kenneally et al. showed training that favored a pyramidal and polarized training distribution.

If you’re unfamiliar with the different training distributions, here’s a quick summary.

  • Pyramidal Training
    • Most training (around 75%) is spent in zone one or at a low intensity. This helps to build your aerobic base and keeps you fresh for more sessions.
    • You will spend around 20% of your training in zone two or around threshold pace. This improves your tempo pace and speed at threshold.
    • You will spend the remaining 5% in zone three or in an anaerobic state. Think of high-intensity intervals
Pyramidal training prescribes a bit more volume in zone two than polarized training, but it's still a great model.
  • Polarized Training
    • Like Pyramidal training, you will spend most of your training in zone one.
    • This is where polarized training differs. Less time is spent in zone two, only around 0-5%.
    • The remaining time is spent in zone three, focusing on improving your top-end speed. Around 15-20% of your total training.
Polarized training offers a very good model for how to run more efficiently.

As you can see in both types of training, a considerable amount of time is spent in zone 2, building your aerobic base.

Here’s the tl;dr: Take most of your miles slow and easy, add high-intensity running about 1-2 days a week, and you’ll be on the right track.

Total Mileage is the Best Indicator of Success

Besides the physiological changes that improve your running, slowing down and running slower allow you to run more miles.

If you’re running near your threshold pace for most of your runs, the muscle breakdown and the strain put on your body will only be sustainable for a short time. Eventually, you’ll hit a burnout point, whether mentally or physically.

One of the best quotes that changed my way of thinking about training is, paraphrasing, “It’s the recovery from training that makes you stronger, not the training itself.”

So let’s look at the evidence for how increasing mileage translates to improved running.

Looking at a study titled World-Class Long-Distance Running Performances Are Best Predicted by Volume of Easy Runs and Deliberate Practice of Short-Interval and Tempo Runs, we find total distance was the biggest determiner of increased running performance.

This study analyzed 85 male runners that were elite and world-class competitive runners.

It found the total distance run had the most significant effect on performance, followed by easy runs, tempo runs, and short intervals.

Most important, however, were the total distance run and easy runs. Easy running was important in better performances due to its “contribution to total distance run.”

In addition, a 2020 study titled Human running performance from real-world big data analyzed over 14,000 individuals and their exercises. This study strengthened the idea of adding more easy miles, as it found faster runners kept much of their training at an easy intensity while slower runners spent most of their training time at higher intensities.

Cover more miles, and your running economy will improve (to a point). And the best way to increase your mileage is to add more easy miles to help your body progress and adapt slowly.

Consistency is Critical

This statement is generally true for anything you’re trying to improve. Want to shoot like Steph Curry? Get up shots consistently. Want to paint like Bob Ross? Get in front of an easel and paint consistently. Want to jam out like Santana? Consistent practice with a guitar is the path there.

The same will hold for running. If you’re not consistently getting out the door and hitting the pavement/trail, any other changes you make will not matter.

It seems odd to say you’re “practicing” running, but that’s all training is. As we run, we optimize our form and stride, our running economy increases, our mental endurance improves, and our body changes physiologically to become more efficient.

The body is a miraculous thing, and it’s remarkable how it adapts to everything we throw at it.

I’ve used the analogy in the past, but think of your training as a stock portfolio. Make regular, intelligent investments, and it will reward you with a big payoff down the line.

Don’t contribute regularly or make bad decisions, and you will be left with nothing in the end.

To quote Shawn Bearden from the Science of Ultra podcast, runners “overestimate how much they can improve in the short term while underestimating how much they can improve in the long term.”

So, How Has This Helped You?

Personally, I’m running more mileage than I’ve ever run before. And by large margins. By applying these principles to my training, my running has improved dramatically.

When I began running, I had no idea what I was doing. I would go out every run and try to hit a pace I deemed “fast,” and this was primarily based on what others were running on Strava.

The result? I was burning myself into the ground. I’d go out for a run and return with my legs cooked more than grandma’s turkey on Thanksgiving. Not only that, but I’d then have to take 1-2 days off to allow myself to recover.

Training like this doesn’t lend itself to consistency, nor is it a way of avoiding injury.

Then I started learning more about running and, more importantly, the best practices to improve.

Since this change, my mileage has increased drastically. I’ve surpassed 300 kilometers/186 miles each month in the past three months. While this isn’t a lot for many, my training progression over the years is what I want to show.

The first year I have tracked is 2019, and that’s also when I started adopting this approach, so we will start there. I started running in 2017.

Slowing down and adjusting my training has showed me how to run more efficiently.

Most notably, I want to point out the increases in total time and total distance.

During this time, I have increased the volume of my easy runs, keeping my intensity manageable. This has allowed me to run more frequently and, in turn, increase how far I run.

I also have run further on individual runs. I’ve run my furthest distances in the past two years—50 kilometers and 77 kilometers. I will also be doing a 100-kilometer run about a week from now.

None of this would have been possible had I not toned it back, slowed it down, and allowed my body to adapt at a more manageable rate.


So, that’s how I’ve adapted my training and increased the frequency, distance, and time I’m able to run. It’s something I’m always preaching to any of my running friends, and I believe the science and adoption by professionals support its effectiveness.

I’m eager to hear from you, though. Did this post help teach you how to run more efficiently? What change(s) had the most significant breakthrough for you and your training? Let me know in the comments.

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