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Endurance Running Fundamentals: How to Run Longer

Has endurance running captured your imagination? This article will teach how to build your aerobic fitness (endurance) so you can run faster!

endurance running

When I first started running more than 22 years ago, I had a singular goal: to become a faster runner.

That goal dominated my thinking for the majority of my running career. But it wasn’t until years later that I realized my thinking about improvement wasn’t exactly right.

You see, I desperately wanted to get faster. So I focused on running faster. I exclusively focused on speed by…

  • Turning every workout into a race
  • Thinking my improvement came from faster workouts
  • Avoiding cross-training, slow running, or higher mileage

By only focusing on speed, I ignored endurance (and I got quite a few running injuries). Because of that, my improvement was relatively slow for the first three years of my career.

But I had much faster improvement at two specific moments in my running career: both senior years in high school and college.

The difference? I made a conscious effort to run higher mileage and cross-train.

The addition of more endurance training was like swapping out my 4-cylinder engine for a V8:

  • On the track, I felt like I was given a few extra gears to run even faster
  • Mileage levels that used to destroy me now felt comfortable
  • Recovery improved and I felt better, despite running more
  • And the results? I got faster in nearly every event that I raced

All it took was a rethinking of the most important piece of training: endurance.

Now, in my own training but also in our training and coaching programs, I emphasize endurance running as a centerpiece of the training process.

As University of Colorado cross country coach Mark Wetmore has famously said:

We have no training secrets. Just the patient development of the aerobic metabolism.

In this article, you’re going to learn about the fundamentals of endurance running: what occurs when you run, how to ensure you’re always prioritizing endurance, and how to make sure you’re healthy enough to run a lot.

What is Endurance?


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At its most simplest, according to USA Track & Field, endurance is the ability to withstand fatigue.

If you want to geek out, endurance is having a highly developed aerobic energy system. More, from USATF:

The Aerobic Energy System makes ATP available for muscle contraction… The aerobic system uses oxygen while producing this ATP [and is] very efficient at producing energy, but it cannot keep up with the demand for ATP when the body is operating at high intensity. Increasing exercise intensity beyond some threshold value causes activation of the anaerobic systems.

Endurance is therefore your ability to exercise in an aerobic state while withstanding fatigue.

Now, think back to your last race. Maybe you were a few miles from the finish of a half marathon. Or halfway through a 5k. Remember that creeping feeling of heaviness that slowed you down?

It grows as the race goes on. Soon, that heaviness will feeling crushing. Your stride rate will slow, you’ll feel less coordinated, and your pace will suffer mightily.

That’s an example of a lack of endurance.

To combat this crushing fatigue, we must further develop the aerobic energy system. But before we figure out how to do that, we must first understand capacity versus utilization training.

Because many runners, especially new runners, overly focus on the wrong type of training…

Endurance Running Fundamentals

Recently my mindset about endurance running was shifted thanks to the book, Training for the Uphill Athlete.

The authors make a point to define training that improves your capacity for endurance vs. training that improves your utilization of that same level of fitness.

Capacity is like your bank account. It determines your spending power.

Utilization is your credit card statement. It shows how you use your spending power.

Capacity training improves your long-term potential. It’s designed to improve the fundamental skills required to be a successful endurance runner. Utilization training, on the other hand, improves your near-term results.

As endurance runners, most of our time must therefore be spent increasing our capacity.

That’s because capacity training leads to structural adaptations. That means, quite literally, that you’re changing the structure of your body:

  • Capillary beds become denser, allowing for more efficient distribution of oxygen
  • Mitochondria (the organelles that produce energy) become more numerous in your muscle cells
  • The heart becomes bigger (it’s a muscle, after all) to pump a higher volume of blood

Structural changes in your body represent changes in your capacity for work. With denser capillaries, more numerous mitochondria, and a bigger heart that’s capable of pumping more blood, you’ll be far more capable of a higher workload.

As long as you’re healthy enough to do more training, you’ll become a faster runner.

How to Train Your “Capacity”

If capacity training is the key to successful endurance running, we must prioritize it throughout the training cycle.

There are numerous strategies for developing the aerobic metabolism. Let’s start:

Endurance Strategy #1: Mileage

Your mileage (commonly referred to as your weekly running mileage) is arguably the best and easiest way to build endurance.

It’s the best way to build endurance because it’s effective. By running more throughout the week and spending more time on your feet, mileage is an excellent proxy for your total workload.

Increase your workload and you’ll increase your endurance.

Running higher weekly mileage levels is also one of the easiest ways to build endurance because the injury risk is lower than the other two strategies listed below (if you’re injury-prone, get our free prevention course here).

Rather than focusing on faster workouts or making one individual run longer, we’re adding easy miles to a longer time period. This makes this strategy easier, safer, and less likely to result in a running injury.

Of course, that’s only if these extra miles are at an easy effort! Keep the effort easy and you’ll thrive.

Endurance Strategy #2: Aerobic Workouts

Especially during the base phase of training, any faster workouts should mostly be aerobic. That means you’re not running faster than your lactate threshold (or tempo pace) for most of the workout.

Aerobic workouts form a crucial pillar in how your training is structured. While they’re not nearly as sexy as a blistering series of 400m repetitions on the track, the goal of these workouts is to improve your potential in the future.

Because of that, you won’t get an immediate boost in performance from aerobic workouts. But that’s not something that will worry you because you’re a long-term thinker…

Examples of aerobic workouts include:

  • Tempo runs done slower than lactate threshold
  • Steady-state or half-marathon paced workouts
  • Progression runs or fast-finish long runs

Most workouts you find in base training will be aerobic workouts oriented toward improving your capacity for endurance.

Endurance Strategy #3: Long Runs

Running for a long time is an obvious winner if your goal is to build endurance. No other type of run more directly improves your body’s ability to resist fatigue than running long.

I’ve long considered the long run to be a priority run during the week. For many runners, it’s THE most important run that they’ll do all week!

For more on this valuable run, don’t miss my recent podcast conversation with coach David Roche:

Much like aerobic workouts, the benefits of long runs take longer to accrue than utilization workouts. So don’t be surprised if you feel tired or sore for awhile after a long run!

The silver lining is that long run gains stay with you for longer. So while you might get fast and sharp from a hard workout, those gains disappear more quickly than the gains from running long.

To again use our finance analogy, long runs are like deposits in your 401(k). Do them consistently enough for a long enough time period, and you’ll be rich (in endurance)!

Endurance Strategy #4: Aerobic Cross-Training

Many runners struggle to complete enough capacity training because they get injured if they run too much or attempt too many long runs. An effective workaround in this situation is to add a healthy dose of aerobic cross-training to your program.

Exercise like pool running, elliptical, or cycling are similar to running and have a nice amount of carryover to your running. As long as this extra exercise is kept at a mostly easy effort, it acts as effectively additional mileage (see strategy #1 above!).

Personally, I’ve used this strategy to great results because I was injury-prone during my running career. In college, I suffered IT Band Syndrome, SI joint problems, Achilles tendinopathy, plantar fasciitis, strained arches, and other irritating injuries.

To get around my own limitations, I started cross-training. Adding 2-3 hours per week of cycling and pool running at a mostly easy effort completely transformed me into a far more capable runner.

The next season I ran multiple PR’s, won my coveted “Most Improved” award, and landed the final competitive spot on our Varsity squad.

All of that was made possible first by my efforts to stay healthy – and then by a decision to train more.

Endurance Running Demands Consistency


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Now it’s time to evaluate your own running. Ask yourself:

  • Do I challenge myself to run higher mileage levels over time?
  • Is the long run prioritized as a key run every week?
  • Do I run a lot of aerobic workouts (or too much high intensity work)?
  • Am I able to add easy cross-training to supplement my volume?
  • Can I stay healthy enough for all this endurance running?

By focusing on capacity-building training, you’ll always be building endurance over time.

If you’re someone who has reached a performance plateau, a lengthy base training period of high volume might be all you need to take your running to the next level.

Or, if you’re someone who wants to run more but can’t due to injuries, then you know injury prevention must be your top goal. After all, you can’t train well if you’re chronically hurt.

The first step is to sign up here for our complimentary injury prevention course. You’ll get an email per day on the major causes of injury, strategies to help you stay healthy, exercise routines for strength, and more.

As I like to say, if you don’t have time for injury prevention, you’ll sooner or later have to make time for injury treatment.

Get started here and let’s stay healthy enough to build our endurance, capacity, and ultimately our performances!

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