The Ultimate Guide to Aerobic Endurance Training
A good aerobic training program should, in practice, look quite simple.
The guiding principles behind a good program may not seem so simple, though.
However, understanding these principles can ensure that you make the progress you’re after without the constant doubting.
In this article, I hope to provide you with some of these principles and get you better results going forward.
Defining ‘aerobic endurance training’
Before going forward, it’s worth getting on the same page with regard to what ‘aerobic’ means and how it differs from its counterpart ‘anaerobic.’
From a purely scientific standpoint, aerobic refers to anything that requires oxygen. Anaerobic refers to anything that does not require oxygen.
Of the means through which your body produces energy some require oxygen (aerobic) and others do not require oxygen (anaerobic).
The energy systems that do require oxygen are ones that are predominately relied on in activities lasting 5 minutes or longer. And, when I say “or longer,” I mean any distance longer- such as multi-hour exercise bouts.
With this in mind, the terms “endurance training” and “aerobic training” are often used interchangeably. To remove any chance of confusion, I just merged them into the same term for the purposes of this article.
This type of training is different from how you would approach anaerobic training, which is usually characterized by anything lasting 3 minutes or less. Examples would include a 400-m or 800-m run for max effort.
The key point here is that aerobic training is mostly limited by your body’s ability to get oxygen out of the air, into your working muscles, and then put to use for turning carbs & fats into fuel.
For instance, your VO2max is a measurement of the maximal (max) volume (V) of oxygen (O2) that your body can use at a given time. You can think of it as the 1-rep max for your heart.
As a result, the specific ways your body adapts to aerobic endurance training will improve its ability to put this oxygen to use.
For the sake of completeness, we will discuss this now.
How do you adapt to aerobic endurance training?
How you adapt to strength training is a bit more clearcut to see.
You pick heavy things up, your muscles get bigger, and then you can pick heavier things up later on.
Yes, there’s more to it, but you get the point. The adaptations to strength training can be much more visual.
The means through which your body improves aerobically is much different, though. Although body composition changes may occur with aerobic training, the real changes aren’t visible to the naked eye.
There are four specific adaptations you’ll make that are often said to be the primary drivers of your improvement.
And, as we mentioned before, they all play a role in how well your body can take up and use oxygen.
They are the following:
Increased stroke volume
Increased muscle capillary density
Increased lipolytic enzyme production
Increased mitochondrial density
1) Increased stroke volume
Stroke volume is the volume of blood your heart pumps out with every beat.
So, the idea of stroke volume increasing means that your heart is able to pump more blood and oxygen through your system with each heartbeat.
As a result, in order to provide the needed oxygen at rest or at any specific submaximal workload, it does not need to beat as many times per minute because each individual heartbeat is more effective.
This is why you will see your resting heart rate and your heart rate at any given running pace decrease over time.
Similarly, the output your heart is capable of at your maximum heart rate will be greater than it was before.
So, all-in-all, your heart itself gets better at what it does.
2) Increased muscle capillary density
When you are on a highway, you use an exit ramp to get off the highway and onto a new road.
Capillaries are the exit ramps your blood takes from your main blood supply (arteries) into the working muscles.
As you improve at aerobic endurance training, you build more capillaries throughout your muscles.
This makes it easier for blood, oxygen and nutrients to get into your muscles and be put to use.
3) Increased lipolytic enzyme production
Lipolytic enzymes are the enzymes that help convert fat into fuel.
Imagine you took two people and had them run a 5k for time. One was highly aerobically trained, and the other was untrained.
The person who is untrained would almost exclusively rely on carbohydrates for fuel. The person who is highly trained would rely on a mix of carbohydrates and fats for fuel.
Why would this be helpful?
Well, when your carbohydrate stores run out, a feeling of true physical fatigue sets in. This is often referred to as “hitting the wall.” It can just feel like your legs are genuinely out of fuel.
If your body can use fats for fuel more efficiently during exercise, and it doesn’t have to rely on carbohydrates as much, then your carbohydrate stores will last longer. Thus, fatigue will be delayed.
4) Increased mitochondrial density
Mitochondria are structures in your cells that produce the majority of energy that your body uses.
This is why your 6th grade teacher called them the powerhouse of the cell.
As you do aerobic endurance training, the concentration and health of your mitochondria increases.
This means that there are more energy producing factories that can be put to work and more energy can be produced overall.
Goal setting
Getting specific about what you seek to accomplish with your aerobic endurance training needs to be the first place you start, because everything else will be influenced by this decision.
This could entail pursuing a specific race or event. If this is the case, you should also determine if you’d like to have a “compete or complete” mindset. In other words, do you want to cross the finish line safely, or do you want to put out your best time?
Perhaps you’re just interested in improving your cardiovascular health. Preparing for any endurance event can help accomplish this, but no specific mode of training may be required to do so.
If you’re interested in using cardiovascular training to supplement your resistance training or improve recovery elsewhere, then the volume and intensities of exercise you need may look different.
Point is: do your best to clearly identify a goal to work toward. Every choice to follow will be more effective.
Exercise selection
The most commonly used modes of aerobic endurance training all have their pros and cons.
Understanding these can help you make better decisions that are in line with the goals you seek to accomplish.
First and foremost, what your overarching goals are within endurance should dictate what your exercise selection is.
This may be obvious, but it is still worth stating.
If you are keen on improving your running, then running may take up the majority of your training. If you are looking to do a triathlon, then swimming, biking, and running should make up most of your training,
However, there can be more that goes into what your exercise selection than just this.
At which point, you would be well served to look deeper at what the differences between difference modes of endurance training are.
Broadly speaking, the different modes of endurance exercise vary in regard to four factors:
Local musculature being used
Some aerobic adaptations happen all over the body, some are specific to the sites being trained.
Example: swimming is predominately upper body while cycling is entirely lower body.
Impact
Self-explanatory
Higher impact activities will usually be more fatiguing and require more recovery than non-impact activities.
Eccentric loading
Eccentric muscle contractions occur when a muscle is lengthening. This can also be thought of as the “lowering” of a weight. For instance, the descent of a squat is the eccentric portion, because the muscles are lengthening. The ascent is the concentric portion.
Exercises with high eccentric demand tend to feel more intense and require more recovery than those without any.
Range of motion
Range of motion refers to how far your limbs must move throughout the movement.
Movements with higher ranges of motion may feel more intense than those with shorter ranges.
Running can be characterized by:
Mostly lower body, some upper body (your arms and torso act as a counterweight)
High impact
Requires eccentric loading
Moderate range of motion (depends on pace)
It is for this reason that running tends to feel the most fatiguing of all kinds of endurance training.
Swimming and SkiErg skiing are both:
Predominately upper body
No impact
No eccentric loading
Large range of motion
Cycling, whether stationary or road:
Is entirely lower body
Has no impact
Has no eccentric loading
Has a moderate range of motion
With this in mind, let’s say your goals are one of the following:
General aerobic fitness development (not specific to any event)
You’re using aerobic training to supplement your strength training
In these cases, you may be better off by focusing on movements that are 1) not overly fatiguing, so you can adequately stimulate your aerobic system, and 2) involve the entire body, so that the site specific adaptations everywhere.
The difference between these two goals would be the volume of training you do. If you are seeking to improve your aerobic system as a primary focus, then the volume you do would be higher than if you were only using aerobic training to supplement your strength training.
Or, let’s say you want to program a cross-training session. This is the idea of using an endurance modality that is not your primary pursuit as an accessory.
A good example would be using a stationary bike for the purpose of improving your running. The reason you would do this is to achieve a similar aerobic response with less fatigue induced.
This could be a bike session all on its own, presuming you are running elsewhere in the week. Or, it could be a 30 minute bike followed by a 30 minute run. The only real limit is your creativity.
In any case, when you are looking to program a cross-training session, you need to identify what you specifically want out of the session. Then, review the various filters provided beforehand and make your decision.
Exercises I would never program
In my view, high rep weight lifting or circuit weight training is the worst way to program for aerobic endurance training.
The reason being is twofold:
First, it is a bit too “in the middle” to effectively stimulate either adaptation (strength or endurance)
It will have a high demand for recovery relative to other modes of training
This can inhibit the amount of aerobic work you can do within a single session or it can hinder performance in subsequent training sessions
The bottom line is this: make sure your exercise selection targets what you want to target with as little chance of fatigue coming from other sources.
Exercise volume, intensity, and frequency
I’m combining volume, intensity, and frequency into the same section because it would be difficult to speak to one independent of the other.
Intensity refers to how hard (or how easy) you are training. Volume refers to how much work you do at each level of intensity. Frequency is just how you split this volume up across the week.
I’ll speak to intensity first and then to volume and frequency after, as it will make more sense that way.
Intensity
There are various ways to measure exercise intensity, but there is one framework I would argue is best: the 3 zone model.
This is going to sound complicated at first and then sound ridiculously simple, so bear with me.
The 3 zone model is different than the 5 zone model. The 5 zone model contains zone 2 training as has been popularized on social media.
The 3 zone model is based off of a metabolic byproduct called lactate.
As exercise intensity increases, lactate production increases. This may serve to inhibit further energy production and muscle contraction.
If you were to graph out the increase in blood lactate levels as your exercise intensity increases, there are two points of note.
First is when you reach 2 mmol of lactate per liter. After this point, lactate starts to accumulate in the blood more rapidly than before.
This is your first lactate threshold (LT1)
Next is when you reach 4 mmol of lactate per liter. Again, lactate accumulates even faster.
This is your second lactate threshold (LT2)
So, that demarcates three points of exercise intensity:
0-2 mmol of lactate per liter of blood
2-4 mmol of lactate per liter of blood
4 or greater mmol of lactate per liter of blood
Do note that this graph would look a little different for everyone.
With training, the line can be pushed to the right. In other words, the fitter you are, the higher your heart rate can get before you hit your LT1 or LT2.
The purpose of using any other means of measuring intensity is to use it as a measure of where you are within this graph, as it’s not too practical to constantly test your blood lactate during exercise.
Heart rate would be an example of a metric that is easy to track and can be used to gauge where you are on this graph.
The key thing with heart rate is that different heart rates correspond to different intensities depending on what mode of exercise you’re doing.
For instance, running has a notable lower and upper body involvement (your upper body serves as a counterweight).
Cycling has only lower body involvement.
When you run, your heart has to pump extra blood to your lower AND upper body. When you cycle, it only has to pump extra blood to your lower body.
So, your legs will be at 2 mmol/L at a lower heart rate on a bike than they will be while running.
So, heart rate works, but needs to be used in context.
Another, far simpler, metric you can use is by just rating your level of effort during exercise as easy, moderate, or hard.
Here, easy corresponds to <2 mmol/L, moderate corresponds to 2-4 mmol/L, and hard corresponds to >4 mmol/L.
It may seem to be over simplistic, but people actually tend to be rather precise with it. After all, this blood lactate curve is largely going to dictate what feels easy, moderate, or hard.
Volume
As I mentioned before, volume is best viewed as the amount of training you do at each level of intensity.
At least, that is how I view it and how you’re likely to see most other reputable coaches or scientists view it.
This produces something known as a Training Intensity Distribution, or TID. In other words, how your volume is distributed across each level of intensity.
How volume is usually measured in terms of distance or duration.
Distance could mean kilometers or miles if you are running or on a bike. Or, it could mean meters if you are swimming or on a rower.
Duration is just as it sounds: the amount of time you spend training.
There are various reasons why you would choose to use one or the other. I will speak to this in more detail in the next session.
As a general rule of thumb, the amount of volume you ‘can’ do is inversely related to the intensity of training.
For instance: you can’t physiologically handle, and recover from, a high volume of high intensity training.
So, most good programs will look something similar to this:
Low volume of high intensity training
Moderate volume of moderate intensity training
High volume of low intensity training
However, the most appropriate TID for you is going to depend on 1) how fit you are and 2) what you are trying to achieve.
Two recent review papers have given some good insight into this.
One of which suggested that the best marathoners in the world are those who gave more focus to high volume, low intensity training as opposed to those who focused more on the higher intensity training.
The differentiator here seemed to be the volume of training, which would have been unobtainable with high intensity training.
The second review paper gave some guidance in regard to how to split up the remainder of your time between moderate and high intensity training.
More specifically, it suggested the your level of fitness dictates which is more important.
For those who are lesser trained, a pyramidal TID was shown to be best- something looking like this:
In this scenario, low intensity training is given the most focus, moderate intensity training has the second most focus, and high intensity training has the least focus.
For those who are more highly trained, a polarized TID was shown to be better. A polarized TID would look something like this:
Here, moderate intensity training takes more of a backseat compared to high intensity training.
Usually though, the amount of high volume & low intensity training being done is higher than what a lesser trained person would do.
Please note, though, that I just made these percentages up to illustrate the point. These ratios do not need to be followed perfectly.
There is a theme here that you should take home. One that may be the most important of this whole article. If there’s any one sentiment that can most usefully guide your training, it is the following.
The primary driver of the results you see within aerobic endurance training will be accomplished through increasing the volume of exercise you do.
THIS is why, in both of the example TIDs I gave you, the high-volume & low intensity training was given the biggest focus.
And, to be clear, it isn’t the low intensity that gives you the results. It is the high volume of exercise that you do. The low intensity just makes hitting this high volume more feasible.
With this said, let’s imagine that you are someone who wants to improve your aerobic fitness, but does not have a ton of time dedicated to this practice.
For example, let’s say you had 20-30 minutes 3x/week.
In this case, you’d be better off not doing any low intensity training. You’d be best served by doing all of these sessions at a moderate to hard intensity.
Reason being: you could train at this volume at a moderate to hard intensity and not have a huge demand for recovery or high injury risk. Plus, if you’re moving faster, you will complete more volume within this time frame than if you were moving slower. So, it is still in line with volume being the primary driver.
I speak more to the idea of time-restrained endurance training in this article.
Let’s discuss another example that would look more like the aforementioned TIDs.
Let’s imagine someone can endurance train 3x/week for up to 60 minutes.
Here’s what an example week might look like:
Tuesday: 60 minutes at an easy pace
Thursday: 40 minutes at an easy pace followed by 20 minutes at a moderate pace
Saturday: Low volume, high intensity session
To go into more specific instructions on in regard to volume prescription is not doable within the scope of this article, in my view.
Such prescriptions are too dependent on your fitness level, goals, mode of exercise, lifestyle, and what the rest of your training looks like (e.g. strength training).
My hope is that these frameworks and generalizations provide enough help to at least get you moving in the right direction.
As always, if you want more specific help or want this all done for you, consider inquiring about 1:1 coaching.
Frequency
As we said before, frequency is just how you split up all of this training across the week.
There are some subjective aspects to this and some objective aspects to this.
Let’s start with the objective aspects.
High intensity training, for example is usually best when done only 1x/week. This is due to how fatiguing it can be and how much recovery it may need.
Long, glycogen depleting sessions such as a long run are also best off when left to just 1x/week. This type of session is also highly fatiguing and a good bit more time consuming than other kinds of sessions.
Short to moderate duration sessions done to a low to moderate intensity are usually recoverable enough to where they can be programmed liberally. In other words, putting this kind of session the day before or after a strength session or high intensity conditioning session is okay.
Using these guidelines should help you fit these sessions into the puzzle that is your life.
Session structure examples
What we’ve just talked about may come off as very abstract.
I’m providing this section so that things can get a bit more real and practical.
The following concepts can apply to any mode of training, as I will just be speaking to programming around volume & intensity.
Low intensity training
As I’ve mentioned before, the purpose of low intensity training is that it allows you to achieve high volumes of training.
In other words, it is the volume that drives results. The low intensity just helps you get there.
Something to keep in mind with low intensity training is that your total weekly volume is what matters most. More than the volume you do in any individual session at least.
Steady state training
The simplest training structure you can use in line with low intensity training is steady state work on a single mode of exercise.
This can further subdivided into short, medium, and long distance sessions. Which, as you can imagine, would all characterize different distances person to person.
One of the purposes of a long session is to reach glycogen depletion (glycogen is your store of carbohydrates). This can serve as a potent stimulus for aerobic adaptation. However, these can be quite fatiguing.
Short and moderate distance sessions can help to increase your total weekly volume without significant fatigue. If you have another training planned the next day that you don’t want to be fatigued for, but want to add to your weekly volume, these can be very helpful.
For example sake, let’s imagine someone for whom a long run would be 10 miles. A short run would be somewhere around 3 miles, and a medium distance run would be somewhere around 6 miles.
This person might look to perform a long run one time a week. Then, the remainder of their steady state runs would be of this short and medium distance to ensure that fatigue doesn’t build to an excessive degree.
Mixed modality sessions
A low-intensity mixed modality session is one in which you use different modes of exercise with all being done at a low intensity.
As an example, here is one that a client of mine is currently performing 2x/week:
Walking
Incline walking
Running
SkiErg
Stairs
Rowing (Concept 2)
As I see it, there are two main benefits to this sort of session.
First, and most obviously, it breaks up the monotony and adds some variety into your training- a common complain with endurance training.
Second, it allows you to specifically train your aerobic system as a whole more specifically.
For instance:
Your hamstrings may limit the incline walking
The impact may limit your running
Your arms may limit the SkiErg
Your quadriceps may limit the stairs
None of which, though, will be present enough to limit the session as a whole.
As you move through, your systemic aerobic energy production is challenged continuously while everything else is challenged intermittently.
If general aerobic fitness is your primary limiting factor, these sessions can be invaluable.
Low intensity intervals
This is something I most commonly program for people who are new to running or for people who are pushing longer distances on running.
If someone is brand new to running, it will likely be impossible for them to run continuously without their heart rate spiking and entering into higher intensities.
A low intensity interval would allow someone who is new to running to accumulate more volume while keeping somewhat of a lid on intensity.
So, say when you run at any pace your heart rate gets to ~155 bpm or higher 5 minutes in or so.
A low intensity interval session could look like this:
Walk for 3 minutes
Run for 3 minutes
Repeat for 5 rounds
Similarly, let’s use our previous example of someone who can run 10 miles as their long run.
Let’s imagine they are in a block of training where they want to make a push on volume, but can’t handle running more than 10 miles at a steady state.
This person could alternate back and forth between 2 mile runs and 0.25 mile walks.
Although it would take more time, they’d be able to cover more distance quite reasonably.
Moderate intensity training
Moderate intensity training can often take the same structure as low intensity training, just with the intensity increased.
Here are some examples:
Steady state training
A moderate intensity steady state session would be the same as a low intensity steady state session with a slight change.
If you were to perform a 60-minute low intensity session, and you let the session be truly low intensity, you will likely feel like you could keep going. Or, in other words, you weren’t overly fatigued.
A steady state moderate intensity session might be 20-30 minutes in duration, except you would try to put out your best performance at this duration.
By way of the session being 20-30 minutes, you won’t physiologically be able to get into a high intensity and therefore the session will be kept to a moderate intensity by default.
Mixed modality sessions
You could structure a moderate intensity mixed modality session in much the same way that you would a low intensity mixed modality session.
You would just push a little harder on each exercise and likely use less total training time.
For the purposes of moderate intensity training, here’s what a session might look like:
10 minutes of cycling @ 100-120 bpm
10 minute incline run @ 150-170 bpm
10 minutes of stairs @ 140-160 bpm
High intensity training
The structure of high intensity training tends to look different compared to the previous two.
At least, that’s true in regard to how I most commonly program it.
The key with high intensity aerobic training is that the bouts of high effort are:
Long enough for them to be aerobic and not anaerobic
Short enough so that your intensity isn’t limited by the need to reach a certain duration
In practice, this usually means all-out bouts of 4-5 minutes at a time.
A simple way to go about this is to just approach it as sets with periods of true rest in between.
For instance one session could look like:
Run for 4 minutes @ max (or near maximal) effort
Rest completely for 3-5 minutes
Repeat for however many sets is planned
Usually 2-4 sets is the most a person can reasonably handle
The other option is using high intensity interval training.
Here’s what an example session might look like:
4 minutes of max effort running
2-4 minutes of running at a 4-5/10 effort
Repeat 3-4x
And, just to be clear, these don’t need to be done with running. Cycling, swimming, rowing, or anything else would work as long as the effort level (intensity) and duration is appropriate.
Whichever of these is best would depend on what your goals are and what the rest of your training looks like.
Conclusion
This article provides, what I believe to be, the fundamental principles required for building a good aerobic endurance program.
There are, of course, more considerations that can be discussed- such as how to mesh this all with strength training or periodization for a given event/race.
In any case, these principles should serve as a good guide to help you get where you want to go.
If you ever need more personalized help or what this done for you, consider inquiring about 1:1 coaching.
Thanks for reading, I’ll see you next time.
