Category Archives: The Runner’s Catch-22

Runners: “Aerobic training” is not the same as “Endurance training.”

It’s common that training which develops the aerobic system is equated with training that increases the body’s endurance. It’s understandable: the aerobic system burns fats in the presence of oxygen in order to provide long-term energy for the body—exactly what it needs for endurance. But the problem is that a powerful aerobic system isn’t the only thing necessary for increase endurance.

The most important difference between “aerobic training” and “endurance training” is this: the former trains a critical supersystem of the human body (the aerobic system), while the latter improves the product of the successful interaction between the aerobic system and many other parts and functions of the body (endurance performance).

What runs isn’t the aerobic system—it’s the entire body. While the aerobic system can be powerful, it can’t perform on its own. Whenever we talk about “performance,” even when the subject is endurance performance, we’re talking about how (and how well) the body uses its aerobic power to create one particular kind of athletic movement.

Roughly, endurance means: “how long the body can produce a particular movement or action without falling below a minimum threshold of performance.”

Another way to say this is that the aerobic power is general, and endurance is specific. Geoffrey Mutai (elite marathoner) and Alberto Contador (Tour de France cyclist) both have extraordinary aerobic systems. In both athletes, all the parts that enable their muscles to be fueled for long periods of time are extremely developed.

It should be noted that in both athletes, we are talking about developing essentially the same parts, developed to comparable levels and talking to each other in very similar ways. Both these athletes also obtain fundamentally the same general physiological benefits—a greater ability to recover, better health, longer careers—all despite competing in wildly different sports.

However, their endurance in specific sports varies wildly. We can expect Mutai to be a proficient cyclist, and Contador to be an able runner, but we can expect neither to have world-class endurance in the other’s field. In other words, Mutai’s endurance is specific to running, and Contador’s is specific to cycling. This is because:

  • Both sports use different sets of muscles: runners use a larger set of muscles for stability than cyclists, since the latter have so many more points of support. Cyclists have the handlebars, pedals, and seat, whereas runners have at most 1 foot on the ground.
  • They load joints in different ways, and use very different ranges of motion: cyclists keep their waist and hips relatively flexed, while runners keep the same joints extended.
  • They use different neuromuscular mechanisms to facilitate endurance: running economy depends on a powerful stretch-shortening cycle, while cycling economy does not.

In my opinion, the stretch-shortening cycle is the most important piece of the running puzzle (and also one of the most overlooked). Running shares a lot of pieces with just about every sport—and developing them is very important if you want to become a good runner. But without an increasingly powerful stretch-shortening cycle, all the power that you develop in any other system (cardiovascular, respiratory, etc.) doesn’t translate into actual running performance increases.

As discussed above, the aerobic system is responsible for sustaining endurance. The best way to exclusively train the aerobic system is by running at a physiologically intensity (below the aerobic threshold).

This is a problem for less aerobically-developed runners: it takes a lot of juice to run the stretch-shortening cycle effectively. In previous posts I discussed how the minimum requirement for running properly is to be able to produce a (very fast) cadence of around 180 steps per minute (spm). This is because the muscles’ stretch-shortening cycle hits peak efficiency around that cadence.

So, these runners often need to run at a higher intensity: they’ll use the maximum output of the aerobic system at max and engage some of the anaerobic system in order to produce a cadence of 180 and properly activate their stretch-shortening cycle. If they fall below their aerobic threshold with the goal of doing “aerobic training,” their cadence falls and the stretch-shortening cycle will largely deactivate.

When I talk about hitting 180, I mean hitting 180 at an average step length: It’s possible for a weaker runner to shorten their stride to artificially increase their cadence without going above the aerobic threshold. But I consider this a rather useless hack, since in my experience it doesn’t really get runners the performance benefits expected of reaching “the magic 180 mark.” (More on this in a future post.)

For a workout to be “running performance training” (endurance or otherwise), it needs to train the key pieces necessary to improve running performance. So whenever you’re not actively training the stretch-shortening cycle, you’re not really doing “running performance training” in my book. “Running endurance training” would be about teaching the body how to run for longer, at a lower intensity, while maintaining a reasonable cadence.

So, whenever an aerobically weak runner trains under the aerobic threshold, I consider it to be quality aerobic training but NOT “running performance training.”

It’s not that their running performance won’t increase—it will. Let me illustrate with a rather extreme example: If playing checkers is the only active thing someone does, playing checkers is better for their running performance than not doing so. But because it doesn’t train the critical systems for running, I don’t think of it as “running performance training.”

Of course, running at a low cadence shares a lot more with running at a high cadence than playing checkers does. But the idea here is to set the highest possible bar for what “running performance training” should mean: training the key systems that running performance rests on. And running without substantially activating the stretch-shortening cycle really doesn’t meet that criteria.

(We can say that running without the stretch-shortening cycle still helps you to improve your running—to a point. But you can’t hope to maximize your performance gains without it.)

For a competent runner (someone who can engage their stretch-shortening cycle at low physiological intensity), “aerobic training” and “running endurance training” become identical: just about all of their training provides all the benefits they need to maximize their running endurance.

What is a less-powerful runner to do with all this information? If I could say only one thing:

Jump rope! Jumping rope (on both feet, alternating feet, on one foot, spinning around, crossing the rope, etc.) is training primarily the stretch-shortening cycle up and down the body, almost identically to the way it’s used in running. IMO, if a runner does only one other thing besides running, it should be to explore and master the jump rope to its fullest potential.

UPDATE Nov 18, 2016: Another (great!) article on the mechanics of running, also touting the potential of jumping rope.

But there’s a lot more than this. Now that I’ve covered all the theoretical ground I absolutely need to cover for my following posts to have any real substance, I can begin to discuss concrete strategies that the runner can use.

Addendum (for the curious): Why do I focus so much on fleshing out the principles (and, more importantly, taking so long to get to the processes)?

Because the idea, of course, isn’t to “balance” aerobic training with performance training. (That’ll only increase endurance.) The idea is to potentiate aerobic training with performance training. (That’ll maximize endurance.) And to turn balance into potentiation, it’s necessary to already have understood the “why.”

The Runner’s Catch-22, Part 2: Power Facilitates Endurance.

In my first post of this series, I discussed a very common training problem plaguing the beginner runner: that it takes a certain amount of power to habitually produce an efficient running cadence (in the ballpark of 180 steps per minute, or spm), and it takes incrementally more power to produce it over longer and longer periods of time.

Enter the beginner, relatively untrained runner, who aspires to run longer races such as marathons. While it’s quite possible to run at 100% of maximum power output for 100 yards, it’s necessary to run longer distances at a decreasing percentage of the body’s total power output: in order to sustain activity for the long periods of time in which it takes to run a marathon, a runner must be working at around 55-65% of their maximum power output.

The problem is that producing an efficient cadence takes power. What happens if it takes 85 or 90% of your total power output to produce an efficient cadence? You won’t be able to sustain that cadence for a mile, let alone a marathon.

(This is a bigger problem than it seems.)

Think about deadlifting a 250 lb barbell. It’s not just about being able to lift the damn thing. At that weight, you should be able to (say) maintain the shape of the lower back, relax the shoulders, and produce a proper hip flexion and extension through the entire movement. The point is that it’s not just nice to be able to meet the minimum power and mobility requirements for the deadlift. You have to, or you’re flirting with injury.

Same thing for the marathon—it’s about being powerful enough to sustain a cadence in the ballpark of 180 spm for the duration of the entire race (for starters). This means that you need to be a good bit more powerful to run a marathon than to run a 5k.

In order to produce a certain cadence for a long period of time, you must be more powerful than to produce that same cadence over shorter periods.

 Over the course of this series, we’ll keep coming back to the same issue: in order to run well, the muscles need to be powerful enough to produce that cadence. If they’re not, they’re less efficient. Let me be completely clear: a powerful runner who can hit 180 spm habitually is more efficient than one who can’t. Let me reiterate this: if you are powerful, you get an added efficiency bonus that a less powerful runner doesn’t have. One last time: if you’re weak, you’re slow and inefficient, but if you’re powerful, you’re fast and efficient.

There is a crazy tangle of ironies to be exposed here: when the muscles are too weak to produce a cadence of 180, it takes a lot more muscle power to be able to run at the same speed. But because your muscles are weak, the speed you are able to run at is much, much slower than you’d expect if you supposed that both the fast and the slow runner were equally efficient.

If you’re powerful enough to produce a cadence of 180 for 50 or 60 miles (in other words, really powerful) you get massive dividends in energy savings.

(This is related to why the “correct” running form—not just for sprinting, but for all running speeds—is the one aligns the body in such a way to help it produce the most power.)

Thanks to this, runners like Jim Walmsley are able to sustain blazing speeds for very long periods of time. Gear Junkie reports that Walmsley recently crushed Rob Krar’s Grand Canyon rim-to-rim-to-rim record, running 42 miles with over 40 thousand feet of elevation gain (and another 40,000 of elevation loss) in just over 5 hours and 55 minutes.

Power is necessary for endurance for very specific reasons. In order to produce endurance—a.k.a. to stay in activity for long periods of time—you need to be burning fuel for long periods of time. But the body’s fuels (fat and sugar) aren’t created equal. The body burns less fats and more sugar as it works at a higher percentage of its total power output—a problem because even a very lean body stores about 100 times more calories in fats than it does in sugars.

Let’s say you’re trying to run at an efficient cadence. The less powerful you are, the more sugars you’ll have to be burning to sustain that cadence. Even if you’re burning 40% sugar to sustain an efficient cadence, you’ll run out of sugars that much more quickly than a more powerful athlete—who might only need to burn, say, 15% sugar to sustain the same cadence.

At some point, you’ll be left with 2 choices: (1) stop running, (2) reduce your cadence (and speed) to the point that you’re burning almost only fats.

Notice how stark these choices are: number one means that you just can’t run as far as the more powerful athlete. And number two means that now that you’ve bonked/hit The Wall—yes, this is what “hitting The Wall” means—you need to run the rest of the distance less efficiently than you’ve been doing so far. Got it? Now that you’re exhausted, you need to spend more energy per mile for the rest of the run.

We’re getting at what it really means to be “ready” to run a marathon—or any other race. It isn’t just about being capable of finishing itin the sense that your body didn’t fall apart before you got to the end. You need to be able to run the whole thing above a minimum threshold of performance. (Now you tell me what that is.)

The Runner’s Catch-22, Part 1

I’m calling this series of posts “The Runner’s Catch-22” to address a very common problem in the running world. A lot of beginner runners—let’s face it—want to run long. Very long. But in attempting to do that, they get ill, injured, or overtrained. And their hopes of running long (and doing so consistently) get quashed.

Running isn’t just about running (as every injured runner knows). It’s about how to run well. But in all sports—in fact, in all movement—there’s a minimum power requirement that must be met: if you want to stand (correctly), your legs, along with your core and spine, have to be able to move into a standing position and be strong enough to support you. If you want to walk (well), your leg joints have to be able to flex and extend to a certain degree, and one leg has to be able to support more than your bodyweight while the other travels through the air. And if you want to run (properly) you have to be able to meet an even more demanding set of requirements. And this is where the story of the “Runner’s Catch-22” really begins.

A lot of things have to be working well for a runner to be powerful—form and movement are vital, for example. Having proper form feeds into your ability to produce power (in the same way that it would work for a weightlifter or a baseball player). So with poor form, you might never be able to meet the power requirement—or go significantly beyond it. So, what is this power requirement?

The body must be able to produce a habitual cadence in the ballpark of 180 steps per minute (spm). 

The body is most efficient at around 180 spm: this is the cadence that best engages the tendons’ elastic component, maximizing the amount of energy that can be taken from the previous step put into the next one. (This is a concept also known as energy return).

UPDATE: For people who are new to running (particularly those who only started being active as adults), meeting that power requirement usually requires a lot of power training, which is a problem for beginners. Experienced runners often are able to produce a cadence of 180 spm easily and habitually, for runs of any distance. (In fact, hitting 180 easily is how I would define “experienced.”) If that’s you, most of this post won’t apply to you.

Power training uses and develops the body’s anaerobic system, which is very powerful, but also produces negative by-products that, in large quantities, are ruinous to the body’s tissues. The anaerobic system is counterbalanced by the aerobic system, which disposes of those harmful by-products and allows the body to remain in activity for long periods of time.

So if you want to be able to train without trashing your body, you need a powerful aerobic system to support the anaerobic system. Just one little problem: while the anaerobic (powerful but dirty) system grows extremely quickly, the aerobic (less powerful but clean) system grows veeery sloooowly.

This is the runner’s Catch-22: Until you have a well-trained aerobic system, it is almost impossible to safely do large amounts of anaerobic training. Trying usually means burnout, illness, injury, or overtraining. But if you can’t do a lot of anaerobic training, you can’t develop power to the point that you can produce an efficient cadence (of 180 spm) at the kinds of low intensities where you can develop the aerobic system.

The wrong move—the one that so many runners take—is to lower their cadence to run more distance. Why? Because they’re set on running, or because they don’t know that there’s better ways to train the aerobic system when you’re not powerful enough to ballpark 180 spm:

  • Cycling/Spinning
  • Walking
  • Rowing

(I’d add bodyweight circuit training to this list, but it’s typically far more aerobically demanding than running would be.)

It’s important to realize that the other option—running at an inefficient cadence while the aerobic system develops—is NOT a neutral, “eh, screw it,” kind of option. It’s not very bad—the aerobic system will probably still develop in time—but it’s not the fastest way to train, and certainly not the best way to guarantee you’ll achieve your goal.

(There’s ways to produce a cadence of 180 at slower speeds, such as shortening your stride. But that opens another can of worms—to be featured in another post of this series.)

Learning a movement pattern the wrong-slash-less powerful way—yes, they really are the same thing—is the best (and probably least-discussed) way to prevent you from performing at a high level. If you learn how to throw a ball by releasing it far forward of your body instead of at ear level, you’ll very quickly plateau in terms of how much force you are able to put into it (meaning that you’ll never throw at 60 mph, let alone 90).

Your body develops through movement. If you don’t move, you don’t use your muscles, which means that your metabolism doesn’t develop.  If you can’t throw a ball faster than 60 mph (because of poor mechanics), your muscles won’t be able to grow in strength beyond what it takes to throw the ball at 60 mph. So your metabolism (aerobic or anaerobic) will never need to grow beyond that.

It’s impossible for your metabolism to grow to be able to produce an energy expenditure that you don’t have the biomechanic possibilities to harness.

Slow or low-cadence running isn’t a death sentence. Slow runners with relatively few biomechanical problems or muscle imbalances do increase their cadence and low-level strength by slow running . . . in time. So it’s often the case that people do end up running much faster and at a much higher cadence after a few months (or years) of slow running. But your power (and your cadence) won’t improve with slow running as fast as it could with actual power and cadence training.

How to get around the Catch-22? Below is the short answer. (The long answer will take a few posts).

  • An overwhelming amount of aerobic training (in sports where you can meet the power requirement).
  • A small amount of running-specific power training (mostly plyometrics).
  • A small amount of running at a cadence in the ballpark of 180 spm.
  • Monitor metrics including HRV (heart rate variability) and MAF (Maximum Aerobic Function) Test to determine your short- and long-term physiological readiness for power training.