How to Rapidly Improve Your Conditioning and Endurance (So You Never Gas Out)
“Endurance is one of the most difficult disciplines, but it is to the one who endures that the final victory comes.” – Gautama Buddha
📚 This is chapter 4 of my book. For other chapters and a full table of contents - go here.
🧠 Also, if you enjoy the subject of endurance and conditioning, and like using your brain, may I make a suggestion - go have a look at my Oxygen Course. It’s truly a masterclass in all things oxygen and taking your conditioning to the next level » click here to learn more.
Let’s play a game…
Would you rather…
Have a car that gets 100 miles per gallon or…
A car that has 600 horsepower??
Now, what about a third option…
How about a car that gets 100 miles per gallon AND has 600 horsepower?
Personally, I’d choose this last option because it means I’m getting the best of both worlds.
I have the efficiency and capacity to go for a long time PLUS the power to put the pedal down and go fast whenever I need or want to.
My goal with conditioning and endurance is the exact same.
But instead of a car, I’m souping up my body to be able to handle whatever gets thrown at it.
Need me to crank out a mile? No problem.
Need me to put a ruck on and go trek through the mountains for a few hours? Easy.
Need me to blast out as many calories as possible on an assault bike in 10 minutes? Done.
It’s this range of options that lie at the center of becoming lifeproof and being antifragile.
By having the bioenergetic flexibility to wield both capacity and power, you unlock greater health and performance, but more importantly, become physically unstoppable and never have to feel limited in your life.
When it comes to conditioning and endurance, the questions we’re after are:
How good are you at getting oxygen from the atmosphere to the muscle mitochondria?
How good are you at utilizing that oxygen?
If you can do both of those things well, then you have a 100 MPG and 600 horsepower engine…
And in this chapter, I’m going to walk you through step-by-step how to make it happen.
Here’s a small taste of what you’ll discover if you read this chapter:
Basic bioenergetics (without this you’ll never understand the difference between immediate and long-term energy)
The #1 way people ruin their conditioning (spoiler - it’s doing too much work in the glycolytic zone)
What energy systems work well together and which don’t (if you want to be rounded, this is key)
The conditioning big 3 (flipping the switch on just 1 of these will explode your conditioning)
How to train your respiratory system (this is how you get oxygen from the atmosphere to the heart)
What the respiratory steal is (and why it’s robbing you)
How to train your cardiovascular system (this is how you get oxygen from the heart to the muscle)
The 2 types of adaptation at the heart (and which you want more of)
What in the world angiogenesis means (and why you can’t have great endurance without it)
How to train your muscle and mitochondria (this is how you utilize oxygen to perform work)
The difference between low days and high days (without this you’ll never build an efficient and powerful engine)
The exact sets, reps, timing, and protocols to use in your conditioning plan (you can plug these in and start getting results today)
Our endurance standards so you can see where you stack up and have goals to shoot for.
As a former 2 sport athlete in college, Keiran is used to performing at a high level across the board.
The mantra that comes to mind is being stronger and more powerful than the guy who’s 20 lbs heavier than you AND faster and better conditioned than the guy who’s 20 lbs lighter than you.
While in college, Keiran checked both of the boxes.
But like many former athletes, when his playing days ended he stopped minding his conditioning.
If you’re a former athlete, you know what I’m talking about…
Just think back to those brutal conditioning sessions during practice and looking around at your buddies thinking “Man…I can’t wait for this to be over…once my playing days are done I’m just going to lift weights and be jacked…screw this conditioning stuff.”
But what Keiran found was that conditioning is an incredibly important piece to the puzzle.
Without it, he wasn’t recovering as fast as he used to, he got winded and out of breath easier and it even started translating to some unwanted joint pain…
That’s when he came on board for Silverback, and in just 6 short months, here’s what happened:
While all those numbers are impressive, the one that jumped out at me and him was his 30% improvement in endurance.
He could go harder for longer and no longer felt limited by his lack of endurance.
Today, I want to help you do the same.
Getting Started - Basic Bioenergetics
In bioenergetics, there are three major pathways:
Pathway 1: Phosphocreatine (PCr) – immediate energy
Pathway 2: Glycolysis – intermediate energy
Pathway 3: Aerobic- long-term energy
These are three primary ways the body produces ATP, and you need to think of them like dimmer switches. They are all on all the time but vary in their contribution depending on the ATP demand.
First up is pathway 3, your aerobic energy system, and it works via the delivery of electrons to the electron transport chain, reduction of oxygen to water, and production of ATP at the ATP synthase complex. This is your preferred method because the only byproduct is water, and it’s what you run on most of the time.
The downside to the aerobic system is its speed. Several reactions must take place, and if the rate of demand for ATP outstrips supply, then you need to have another option.
The fastest pathway is PCr - pathway 1. It’s literally a single reaction where PCr donates its phosphate group to ADP to reform ATP. SUPER FAST. If you want to go sprint 60 yards, then PCr is the primary driving force making that happen.
A common oversight is that you need to reload creatine to maintain a high concentration of PCr in the cell. How do you think this happens? Well, it happens because of pathway 3. The ATP generated at the mitochondria is used to reform phosphocreatine from creatine so that the next time you have to do anything that’s short, powerful, and explosive, you are ready to party.
That means if you are performing repeat sprints, PCr is the main driver of the sprint, and aerobic metabolism is working its ass off during your recovery to replenish the PCr pool.
So, pathway 1 and pathway 3 have a very symbiotic relationship. The oddball out in this equation is pathway number 2: glycolysis.
Glycolysis (better known as anaerobic glycolysis) refers to the production of ATP without oxygen, and it’s generally thought to power activities lasting 15-60 seconds. If you go run 400 meters as fast as you can, you will experience how nasty glycolysis is firsthand. You will be swimming in the acidic hell bath that is non-oxidative metabolism.
The downside to doing lots of glycolytic work, though, is that it interferes with aerobic adaptations. Just think about this logically. If you continually send the signal that you need to optimize to live in a world without oxygen, what do you think will happen? You will begin downregulating all oxygen-related machinery.
This is why you do glycolytic work sparingly - it comes at a great cost and directly interferes with just about everything else you are trying to accomplish in training.
Think of it like an interference signal:
Pathways 1 and 3 are like constructive interference. You can train them while also prioritizing strength, power, or hypertrophy, and they have an additive effect.
Pathway 2, on the other hand, is like destructive interference. It doesn’t play nice and tends to cancel out other signals.
If you want to be a strong, ripped, well-conditioned human, then you will not make the mistake of doing glycolytic-style work too often. It can be a powerful tool, but only when it’s used appropriately.
The Conditioning Big 3: Respiratory, Cardiovascular and Muscular
As you can see in the image above, there are three systems at play here: respiratory, cardiovascular, and muscular.
When it comes to the oxygen cascade they each play an important role, so let’s unpack them one by one.
Respiratory System - Getting Oxygen from the Atmosphere to the Heart
In health, the respiratory system very rarely limits oxygen supply. The two primary ways it can are:
Increasing red blood cell velocity through the pulmonary circulation to the point that it doesn’t load with oxygen.
The likelihood of you falling into this category is very slim. You only see it in very high-level aerobic athletes, like professional cyclists, with massive cardiac outputs.
Shunting blood flow away from exercising muscles to the respiratory musculature as they fatigue.
This is known as the respiratory steal and can affect anyone. As your respiratory muscles fatigue, they will demand more blood. And seeing as breathing is more important than your quads, you will decrease blood flow to your quads in favor of muscles that impact inhalation and exhalation.
This begs the question, how do we minimize the respiratory steal?
Fortunately, there’s a simple answer: do things at high intensities that make you huff and puff. Like 90-second all-out repeats on an assault bike.
Your respiratory muscles will adapt just like any other muscle, and eventually not have to steal as much blood.
Cardiovascular System - Getting Oxygen from the Heart to the Muscle
As we transition to the cardiovascular system we must discuss the difference between supply and utilization - the two variables we will continue to refer to as we unpack this oxygen story:
Supply is the amount of oxygen delivered to a working muscle and is dependent on blood flow. Assuming you have no issues loading oxygen in the lungs, we can assume that increased blood flow equals increased oxygen supply.
Utilization is your ability to extract and use oxygen at the muscle.
Think of it this way…
You have a hose that oxygen can diffuse in and out of. That hose runs by a balloon that will pull some of the oxygen out as it flows by. Let’s say you have two hoses and two balloons. We’ll call them hose+balloon A and hose+balloon B. You take a sample from each hose right before it reaches the balloon, and they both are supplying 100 units of oxygen. You take another sample immediately after the balloon, but now you find a difference. Hose A only has 40 units of oxygen left in it, while hose B has 60 units of oxygen in it.
Which balloon then extracted and utilized more oxygen?
Balloon A did, of course, and it thus has a higher VO2 (volume of oxygen consumed). If you like math, this is where the Fick Principle comes in handy:
VO2 = Q (a-v O2 difference)
Or more simply
VO2 = (supply)(extraction)
To maximize VO2, you must drive supply and extraction as high as you can. We are going to start the conversation about how to accomplish this with the cardiovascular system.
We break the cardiovascular system into central and peripheral components. The central component consists of the heart, while the peripheral component consists of the vasculature (arteries and veins) throughout the body.
Supply is equal to cardiac output, which is the product of heart rate and stroke volume. Think of cardiac output as setting the ceiling for supply. You cannot go higher than your max cardiac output.
Your max heart rate isn’t trainable, as the evidence shows minimal differences in well-trained versus normal humans with regard to heart rate. Therefore, the variable of interest becomes stroke volume.
As you can see above, numerous factors impact stroke volume, but we are going to summarize it like this - to maximize stroke volume, you want to maximize fill and contractility.
If the heart 1) fills with more blood and 2) drives more blood out per contraction, then stroke volume increases.
In theory, you increase fill by doing low intensity (heart rate somewhere between 110-140 BPM) long duration (30 min to several hours) steady-state cardio. This works because the low heart rate allows the left ventricle to fill maximally with blood and stretch, causing an eccentric adaptation (think make the chamber bigger).
To maximize contractility, you need to dial up the intensity and go hard. Bursts of 5 min all-out sets work by increasing afterload - the pressure head the heart must contract against.
When you are peddling your ass off on the assault bike, think about the muscle contractions taking place and how intense they are. Now think about the vasculature running through that muscle and how it will get clamped off like pinching a hose. This is the force the heart must overcome. In order to contract and drive blood out, it must overcome this potentially massive pressure head.
Over time, what do you think this does to the heart?
It forces it to remodel by growing more muscle. This is known as concentric remodeling and improves the contractility of the heart.
The image below provides a really nice visual to help you distinguish between fill (eccentric) vs. contractility (concentric) remodeling.
To drive up stroke volume as high as possible, you want a bit of both, and here the basic guidelines:
Alright, let’s transition and talk about the peripheral component of the cardiovascular system and how it contributes to both supply and extraction. To best understand this, I’d like to bring back our good friend Adolf Fick and his law of diffusion.
As you can see above, diffusion is proportional to the area, diffusion constant (don’t worry about this), and pressure differential, and inversely proportional to the thickness. The relevant variable is the area because a larger area means greater diffusion. Greater diffusion means greater extraction. And greater extraction means more oxygen delivered to the muscle mitochondria.
Recall our hose and balloon example from earlier. What happens if one balloon has two hoses running by it, while the other only has one? Which balloon has the potential for a higher VO2? The one with 2 hoses because the surface area for exchange is greater.
Now all you have to do is extract this little analogy and apply it to capillaries (hoses) surrounding muscle (balloon).
Greater capillary density does two big things for you:
It raises the ceiling for supply – more hoses mean more blood flow, and more blood flow means more total oxygen supply.
It increases surface area – greater surface area means greater diffusion, which means greater extraction.
So, for the peripheral side of the cardiovascular story, your #1 goal is to increase capillary density as much as you can.
Before we talk about how to do this, I’d like to touch on the last player in this story: the muscle mitochondria.
Muscular - Getting Oxygen from the Vasculature to Your Mitochondria to Do Work
The mitochondria, as you may have heard, is the powerhouse of the cell (amongst about 1000 other critically important functions) and drives aerobic ATP production. The oxygen travels to complex 4 in the electron transport chain, grabs an electron, and combines with two protons (H+) to form water.
Oxygen showing up at complex 4 allows for the aerobic ATP production line to keep operating smoothly.
You take away oxygen, and bad things start happening…like electrons not moving through the electron transport chain, protons not being pumped, and ATP not being generated. This is why we love oxygen.
Let’s do a quick thought experiment. Say you have two pieces of muscle, muscle A and muscle B. Muscle A has 5 oxygen-eating mitochondria, and muscle B has 25 oxygen-eating mitochondria. Which muscle has greater oxygen-consuming, and thus ATP-generating abilities? Muscle B does. And that’s what you want when you’re trying to build a big engine – lots of mitochondria!
The million-dollar question then is how to do it?
I waited to talk about how to grow more capillaries because capillaries and mitochondria tend to go hand in hand, so now we can kill two birds with one stone.
There are 2 major variables to consider, and they are the same ones we’ve already discussed:
Of the two, intensity is the strongest stimulus behind mitochondrial biogenesis (the growth of new mitochondria) and angiogenesis (the growth of new capillaries). However, if you crank up duration high enough it can drive those adaptations as well.
So, you get to pick your poison, and doing a blend of each is what I recommend.
Not the sexiest of answers I know, but it works. Do some things at max RPM for a short period of time (2-5 min) and do some things that are low RPM for longer periods of time (30 min to several hours). This ensures you are building a complete engine that has big-time horsepower as well as high miles per gallon.
This is a surface-level overview of a highly complex topic, but that’s intentional. You don’t need to reinvent the wheel to build a robust, generalized aerobic engine. If you wanted to win the Tour De France, this would be a very different conversation.
For our intended purposes, though, this will get the job done: have low days, have high days, and manage that stress throughout the week based on your current goals.
Let’s recap how you’re going to build a 600 HP and 100 MPG engine, and then shift to the specific guidelines:
Your goal is to maximize the volume and rate of oxygen you can consume by maximizing stroke volume, capillary density, and mitochondrial density.
You can achieve this by doing a blend of low and high days.
The PCr and aerobic energy systems have a constructive effect
The glycolytic energy system has a destructive effect
Endurance and Conditioning Training Guidelines
Below are the exact templates and protocols you need to build an engine that has great efficiency, capacity, and power.
Low Days - Maximizing Efficiency and Getting 100 Miles Per Gallon
The key to low days is appropriately managing your intensity. They should feel easy, and you should never exceed a 7 out of 10 in terms of effort level. If you can’t breathe through your nose or carry on a conversation, then you are likely going too hard.
Volume on these should steadily increase over time, so don’t get impatient and make huge jumps.
Also, be sure to track your progress by measuring distance or average wattage at a particular heart rate. If either goes up with heart rate staying the same, then you’ve improved.
Option A: Low-Intensity Tempo Training (LIT)
Heart rate should be back down to 120 BPM by the end of rest and reach 150-160 BPM by the end of work. The best modalities for this are running, biking, rowing, ski erg, versa climber, sled pushes, etc. Really anything that’s easily repeatable gets the job done.
Option B: Low-Intensity Steady State Training (LISS)
The best modalities are biking and hiking, but you can also run or do some type of circuit.
I’d only use running here if you want to do a 5k, 10k, or half marathon. Really long runs may interfere with other strength/power/hypertrophy etc. goals. However, if you have an endurance event that requires running for longer than 40 minutes, then adjust accordingly.
High Days – Maximizing Power and Getting 600 Horsepower
High days are much harder to generalize than low days, but we can still come up with some solid guidelines. For a LifeProof Athlete, I like to think about high-output events lasting anywhere from 2 minutes to 30 minutes. If you were to visualize that on a bell curve, it’d look like this:
As work time decreases, you are prioritizing power, and as work time increases, you are prioritizing capacity. Similar to the example from the hypertrophy chapter, your sweet spot is likely 8-12 min working sets because you get a blend of both.
It’s important to distinguish the intensity ratings because I don’t want there to be a misunderstanding. The intensity on the far right of the curve (to the capacity side) says low because it has to be for you to survive 25-30 minutes. That does not mean you are caking it. This is still a gas pedal-down exercise. You are going max output for 25-30 minutes and leaving nothing in the tank.
For example, think about running 100 meters as fast as you can versus running 1 mile as fast as you can. If you tried to run a mile at your 100-meter pace you’d never make it. That doesn’t mean you are taking it easy when you the run mile, it just means you pick the highest pace you can sustain for the task at hand.
It doesn’t matter where you fall on the curve, it should be hard, it should be a fight, and it should be brutal. If you walk away feeling unscathed, then you went too easy. These are all about intent, and if you don’t show up with the intent to be a badass, then these will not work.
Also, if you’ve never seen work-to-rest ratios, they work like this:
1:1 means work time and rest time are equal. If you work for 2 min, then you rest for 2 min.
1:0.5 means you rest half the work time. If work time is 5 minutes, then you rest 2.5 min.
Option A: Highest Intensity Intervals
If you're confused by work:rest and rest between sets read this footnote.
Option B: High-Intensity Intervals
Option C: High-Intensity Continuous
Example - 25 minutes for max calories on an assault bike.
Conditioning and Endurance Standards
Here’s how our athlete classification system works (note: we have very high standards and you should too):
Level 1 = Human
Our baseline expectations for any functioning human
Level 2 = Human+
You laugh at mere mortals
Level 3 = Lifeproof Human
You are beginning to enter a league of your own
Level 4 = Iron Human
You are a savage
Level 5 = Super Human
You have evolved into a new species
Here are the numbers specific to conditioning and endurance.
If you’ve enjoyed this foray into endurance and conditioning, then I think you’d really enjoy my Oxygen Course.
I go into far more depth to unpack the underlying physiology, and if you’re the type of thinking athlete or coach that likes to understand what’s happening under the hood, then I’d love to invite you to check it out.
Be warned though…
It is dense and I hold nothing back.
You will be challenged to use your 🧠 and think on a level that you maybe have never done before.
So enter at your own risk.
Otherwise, post any questions you have in the comments below and thank you so much for being here.
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🏋️ Principles of strength and conditioning course – this is where I show you how to empower your own performance by teaching you to write training programs that get record results in record time for your physique, health, and performance.
💨 The oxygen course – this is a course for those brave souls that want to dive into the weeds and learn graduate-level respiratory, cardiovascular, and muscular physiology without the graduate school price tag.
As measured by his 10 min assault bike challenge
From experience, it’s good to blend it in once every 3-4 months and should be prioritized when 1) all you care about is a singular effort (such as running one all-out sprint) or 2) compete in a sport like hockey that relies on this energy system big time.
Before you ask me about breathing masks, it doesn’t look like they do anything beyond what hard intervals already do. Besides cost you extra money.
The reason I say in theory is that the jury is out on whether or not you can make appreciable changes to the structure of the heart after your early 20’s. But this story is unclear, and more evidence is needed.
Termed angiogenesis if you like big words)
Among other things we didn’t discuss like enzymes and muscle fiber type
Pro tip: I like putting my direct arm and delt work after these low conditioning days. It’s like a reward for getting my inner meathead to do his conditioning.
If you’re confused about work:rest vs. rest between sets, then read here. Work:rest is how long you rest between reps. For example, if you want to hit 6 reps of 2 min all out on the assault bike you’d rest 2 min between reps. That’s work:rest. Now, if you wanted to hit multiple sets of that (say 2 sets of 6 reps) then you’d rest 5-10 minutes between sets. That’s rest between sets and you do it to allow the athlete to recover and maintain quality power output. If you tried to hit 12 reps straight of 2 min all out work, I’d bet the house that reps 8-12 get sloppy and see a significant drop off. You’re better off breaking the work into two sets to ensure quality is maintained.