“The most important thing now is to get mileage in and stay injury-free.”
I kept repeating this sentence as I slogged up the tiny hill in my local park, wondering what passing runners would think of me and my snails-pace. The urge to speed up and prove to myself (and those other runners) that I could run faster was strong.
But I resisted. After all, I only started running 5 months ago, and having only 3 months left until my first ultramarathon, I couldn’t risk an injury now.
So I plodded on, reminding myself that today, all that mattered was that I got the mileage in, no matter how long it took me.
When I registered for my first ultramarathon – a 61 km trail race – just 5 months prior, I was far from being an endurance athlete. While almost daily kettlebell training has kept me strong and healthy since 2015, it has not been building my aerobic engine to a meaningful degree.
I trusted that the many years of heavy lifting had strengthened my tendons and bones enough to withstand the stress of traveling 61 km on foot, but I doubted my cardiovascular system and muscles were sufficiently conditioned to take on this task.
Applying my knowledge as a fitness enthusiast and science nerd, I decided the best way to quickly build mileage and stay injury-free was to focus exclusively on easy running. Once I had completed my first race, I could add in higher-intensity training.
I crossed the finish line of that race as 3rd female and have since finished various other (and much longer) ultramarathons. My journey from that starting point to my current training taught me valuable lessons about the art of easy running. I learned that the “easy running” equation becomes much more complex as you develop as a runner.
But first things first. What is “easy running,” and why is it the backbone of any ultramarathon training plan?
Understanding Easy Running: The Science Behind the Shuffle
Aerobic Deficiency Syndrome (ADS)
I first encountered the term “Aerobic Deficiency Syndrome” (ADS) in the book “Training for the Uphill Athlete,” written by Scott Johnston, Steve House, and Kilian Jornet. And looking back to my beginnings as an ultrarunner, I’m pretty sure I suffered from this condition. Why? Because ADS describes a phenomenon where people lack aerobic fitness.
It typically occurs when athletes spend too much time training at moderate or high intensities and very little or no time training at very easy – true aerobic – intensities. And since most of my kettlebell training sessions were high intensity and I rarely did purely endurance-type activities at a low intensity, I had a massively underdeveloped aerobic base.
To understand why, we first need to understand how our body uses energy. Depending on exercise intensity, our bodies primarily use fats, carbs, or a mix of both. Two key thresholds determine these zones: the aerobic threshold and the anaerobic threshold.
Below the aerobic threshold, your body primarily uses fat for fuel. This is highly efficient and sustainable, allowing you to keep going for hours – perfect for ultrarunning. When you cross your aerobic threshold, you enter what some coaches call the “middle zone.” In this zone, your body uses a mix of fats and carbohydrates for energy, but it’s less efficient than staying purely aerobic.
Push harder still, and you hit your anaerobic threshold, above which your body primarily relies on carbohydrates for fuel – a limited and unsustainable energy source for long efforts.
Here is where it gets interesting: You can train your body to become more efficient at using fat as your primary fuel at higher intensities. And elite endurance athletes have done just that. They often have a small “middle zone” because their aerobic base is larger.
But for those of us with ADS, that middle zone is huge because we aren’t efficient at burning fat for fuel. When I started, I probably didn’t have a true “easy zone” – even my slowest running pushed me above my aerobic threshold. This is common for beginners or those from high-intensity training backgrounds. Our bodies haven’t developed the cellular machinery (like increased mitochondria and capillary networks) needed for efficient aerobic energy production.
This is precisely why easy running is crucial in ultrarunning training. By consistently training at truly easy intensities—even if that means walking at first—we gradually build the aerobic base we’re lacking. It’s like laying a foundation: We need to develop those cellular adaptations before we can effectively add higher-intensity training to the mix.
How To Find Your “Easy Pace”
Now that you understand the “why” behind easy running let’s talk about the “how.” In my experience, many runners think they’re running “easy” when, in reality, they’re not. Often, this is because running truly easy can feel uncomfortable and excruciatingly slow, especially for new runners or those who exhibit symptoms of ADS. While there is no perfect method for determining what your easy pace should be on any given day, there are a variety of methods you can use:
The Talk Test: Your Most Reliable Guide
When I started running, I primarily relied on this method because I understood it instantly, and there was no need for any calculations or advanced running gadgets. Over the years, I have also found this method to be the most reliable and straightforward.
You simply have to check in with yourself if you can comfortably hold a conversation at the current speed you’re moving. If you have trouble speaking in complete sentences, you go too fast.
This can be a humbling check for many runners, especially those who live in mountainous areas, and find out that they would need to walk most (or even all) of their uphills to keep their effort truly “easy.”
Rate of Perceived Exertion (RPE): Learning to Listen to Your Body
The rate of perceived exertion (RPE) is similar to the talk test in that it teaches you to listen to your body. I have already described the RPE scale in my article number 2 of this series, where I talked about the different types of training runs that should be included in a well-rounded ultramarathon training program. Generally speaking, the RPE scale and the talk test are related, but rating your effort according to the RPE scale takes some time to learn. Using the RPE-Scale of 1-10 (see picture below), your easy runs should fall between a 3 and a 5. An easy run should leave you feeling good, not tired or “accomplished.”
Heart Rate Training: Numbers Don’t Lie
If you are a data nerd like me, you might like to train according to heart rate. However, while heart rate training might seem like a perfect objective solution to the “I don’t know how easy I should run” problem, the truth is that it’s not the perfect solution many runners believe it to be.
And many runners make the mistake of relying on their watch’s heart rate zones.
Why is this a mistake? Because heart rate zones are highly individual and must be set for each person individually. The commonly used formulas (like Maffetone’s 180-age) provide only a rough starting point – they’re not one-size-fits-all rules.
Besides, factors like genetics, age, fitness level, running experience, stress levels, sleep quality, and even medications can affect your heart rate response to exercise.
Heart rate training might be even less useful for trail- and ultrarunners. When the terrain is highly technical and comes with lots of elevation changes, your heart rate naturally fluctuates more than on flat ground. And often, there’s a lag between effort changes and heart rate response. Walking every tiny hill and interrupting your natural rhythm of moving over challenging terrain just to maintain a specific heart rate is counterproductive to your development as an ultrarunner.
That’s not to say heart rate is not a valuable tool for ultrarunners, but it should not be your primary one to determine if your run is “easy” when moving over trails and routes that feature a lot of elevation changes.
I primarily use RPE to gauge effort during a run and check my heart rate data afterward or during flat sections on nicely groomed trails. Using every tool – from heart rate data to perceived exertion to the talk test – gives us a more complete picture of our training intensity.
Think of it like having multiple gauges on your car’s dashboard: while speed is important, you must also monitor the temperature, fuel level, and engine health.
The same goes for running – combining different feedback methods helps ensure you’re training in that sweet spot for aerobic development.
Easy Running in Ultramarathon Training
Easy runs form the backbone of any good ultramarathon training program. Without enough easy volume, you won’t be able to maximize your aerobic fitness, which, as you now know, means you won’t be able to sustain relatively higher speeds for long.
However, not all easy runs are the same. The more you develop as a runner, the more your easy paces will vary, and each “easy run” ’s purpose will differ. Whereas absolute beginners might have only 1 easy pace (because almost all running will feel “hard”), a more developed athlete can further divide their easy runs into:
- Recovery runs: These will be your easiest runs and are typically scheduled after a hard workout or long run. You can not go too slow during these runs; some days, you will be more shuffling than running.
- Base-building easy: These runs form the bulk of your training and develop your aerobic base. They are still at a conversational pace, but you can pick up the pace and, when feeling good, even progress to a marathon pace. Just don’t force yourself to go fast on an easy run.
- Long runs: Many ultrarunners keep those runs entirely easy (especially during base building), and for many, the long run includes back-to-back long runs. However, fast-finish long runs and pace-changing long runs are valuable (yet often underutilized) tools in an ultrarunner’s toolbox.
Understanding how to balance recovery and base-building easy runs is key to sustainable progress as an ultrarunner.
Learning to interpret your body’s signals correctly and adapting your training accordingly is one of the most crucial skills you can learn as an ultrarunner. Some days, you may change a planned base-building easy run into a recovery shuffle; other days, you may find yourself with unexpected energy and push the tempo a bit. However, ensure you stay within an RPE range of 3-5 for the entire session.
Special Considerations for Trail Ultrarunners
Trail running adds another dimension to “easy” effort. I run both road ultramarathons and mountainous trail ultras, and when training on technical terrain, I approach my “easy” runs slightly differently than when training in my local park and on the streets of the big flat city of Berlin (where I currently live). Here’s how you can approach your easy runs when varied and technical terrain makes it hard to keep a consistently low effort level:
The Art of Power Hiking
One of the most significant mindset shifts for new trail ultrarunners is accepting walking as part of training. Power hiking isn’t a sign of weakness – it’s a crucial skill. When training for a mountain race, practice hiking in training, even on hills you could run. Most people will hike during long mountain races (even the elites), so train those hiking muscles.
Technical Terrain
Easy effort on technical trails doesn’t always feel “easy.” Your heart rate might spike as you focus on navigating rocky or slippery sections. Focus on maintaining relaxed breathing and smooth movement, and let your heart rate do what it will.
Apply the “Effort Equilibrium Rule”
When training on hilly terrain, I use what I call the “effort equilibrium” approach:
- Slightly easier effort on uphills
- Maintain easy effort on flats
- Purposeful, yet controlled on downhills
This approach helps maintain a more consistent overall stress on your body, even when the terrain is constantly changing.
The Art of Patience: Making Peace with Easy Running
Embracing the “easy run” can be a struggle for many runners, ultrarunners included. If you’re like me, you may feel embarrassed by how slow your easy runs will be at first – especially if you’re just starting out on your running journey or are dealing with the symptoms of Aerobic Deficiency Syndrome.
However, the plod will be worth it. Through exclusively easy running at the beginning of my ultrarunning journey and plenty of it throughout my journey, I have been able to stay injury-free despite quickly ramping up my running volume to a high level and finishing my first 24-hour race and 100-miler strong already in my second year of running.
The next time you want to push the pace on an easy day, remember that embracing the art of easy might be the key to unlocking your full potential as an ultrarunner.
Note: This is part IV of the Ultrarunning for Beginners series. The previous articles in this series can be found here:
Part I: So You Want to Run an Ultra-a Guide to Getting Started
Part II: Building Your Ultra-Training Foundation: From Plan to Practice
Part III: Beyond Easy Miles: Understanding Different Types of Training Runs