conditioning for special operations selection training by building the elite

Conditioning 101: A Guide for Special Operations Selection Training

The traditional conditioning model is antiquated and inaccurate.  In this article, we’ll introduce how to implement a new model of conditioning for special operations selection training.

Energy systems (the metabolic pathways involved in conditioning) are broken down into three components or subsystems, which collectively comprise the larger energy system created by all three of them functioning together.

The three subsystems: 

  • Alactic (ATP-PCr), which predominates during short, powerful bursts of energy, such as in a 10-12 second sprint. 
  • Lactic (glycolytic) – aka anaerobic, credited with bursts of output lasting for about 60-90 seconds of continuous effort. 
  • Aerobic, which can keep going for hours without a break. 

The antiquated model is to treat each of the three subsystems as independent pieces of the conditioning puzzle. And, consequently, to assume that you need to work on each of them separately

This is why people say things like ‘aerobic conditioning’ or ‘anaerobic intervals’ when explaining the type of conditioning they are performing. These methods (and labels) aren’t ineffective or completely inaccurate, they are just incomplete. The traditional ‘aerobic/anaerobic’ model doesn’t hold up well under scrutiny because all three subsystems work simultaneously in any event.

The conventional way of illustrating this looks like this:

When we describe energy systems in terms of seconds or minutes, this representation is accurate enough. But at the level of milliseconds in between individual muscle contractions, there is a lot more going on. 

First, we have to talk about lactate. Historically, lactate has been thought of as a pesky metabolic byproduct and driver of fatigue. But this conclusion hasn’t aged well.  More recent research has pointed out that researchers could have just as easily seen lactate as part of the body’s effort to fight fatigue. 

In fact, lactate is an important link between the lactic (anaerobic) and aerobic energy systems. It’s a product of glycolysis and a rapidly-available fuel for the downstream process of mitochondrial respiration. This flux occurs continuously, even under fully aerobic conditions, and happens throughout the body.   

Much of this interplay happens in very rapid exchanges measured in milliseconds during and between muscle contractions. During each contraction, the alactic (phosphocreatine) and lactic (glycolytic) systems provide energy for muscle contractions, and between those contractions, the aerobic system helps to replenish them. Some of the fuel used by the aerobic system during this process is lactate, which is shuttled in from the lactic system. 

There are multiple routes to fatigue, including central factors coming from the brain, but in the metabolic sense, fatigue seems to be less about a lack of oxygen or glycogen and more about an insufficient glycogen flux rate that can’t keep up with the pulses of energy necessary to initiate muscle contraction. Rather than just the total available pool of glucose or glycogen, a major factor is in the rate-limiting role of the aerobic system as it works between contractions via oxidative phosphorylation. It’s the flow (or flux), not the stock of the energy supply that becomes the limiting factor. Again, what’s important is how the systems work together rather than what they’re doing independently. 

No matter the type of workout you’re doing, you’re never working on just one system. We need a better model to describe how this works – something that accounts for the constant interdependence of each subsystem and breaks up aerobic adaptations into categories that you can target. 

Let’s dive into that.

A Better Conditioning Model 

A more updated model of energy system development involves breaking training methods into three categories. 

Let’s use an analogy to help conceptualize how energy systems work.  

Imagine that your body is similar to a car with a combustion engine. An engine has three main factors that affect its performance:

  • Fuel system – how gas gets into the engine
  • Engine – where combustion (energy transformation) occurs that moves your car
  • Intake and exhaust – how air (½ of the fuel equation) and exhaust (waste products from the engine) leave the vehicle

Keep this in mind as you continue reading. 

Training focus: Delivery

Delivery-based methods are designed to improve your ability to deliver fuel to tissues and clear waste products from them. They involve these types of adaptations: 

  • Your heart’s ability to move blood through your body
  • Capillaries’ ability to handle the movement of that blood
  • The density and capability of mitochondria in local tissues
  • Coordination of various subsystems to facilitate delivery

During these types of methods, you’re generally doing lower intensity, longer-duration activities where constant delivery (and consistent utilization) becomes the limiting factor over time. 

Going back to our car analogy – this type of work is like improving your fuel system. It improves the potential of your motor by providing more fuel at a faster rate to the engine. You can have a 1000 horsepower engine, but if you have a tiny fuel pump that only provides a small amount of fuel, you can’t express that power. 

Training focus: Utilization

These methods stress how quickly you metabolize oxygen, glucose, lactate, etc in working muscles. Here, you’re using fuel faster than it can be delivered or replenished. Thus, it is what is traditionally called ‘anaerobic’ or high-intensity aerobic training (think threshold intervals). 

Utilization training leads to the following adaptations:   

  • Rate of metabolizing lactate and oxygen
  • Increased resistance to acidosis

Returning to our car analogy, this type of training is developing the internal components of the engine so that you can produce more horsepower or use fuel at a faster rate. If your fuel system is more powerful than your engine can handle, then it doesn’t matter how much you step on the throttle, you still won’t be able to produce more power.  

Training focus: Breathing

Breathing is simple – it’s how you move air in and out of your lungs. Oxygen is the primary fuel and CO2 is the main waste product. If you can’t move fuel into your body and get rid of waste, it doesn’t matter how capable the rest of your body is. 

We wrote an entire article on breathing that you can find here. Breathing training focuses on: 

  • Movement, which is usually the main limiter of breathing (poor position = ineffective breathing mechanics).
  • Once that’s taken care of, coordination and fitness of respiratory muscles become important. 

In our car analogy, breathing is your air intake and exhaust system. If your breathing can keep up with your fuel delivery and engine, you’ll extract every ounce of horsepower you can out of the entire system for as long as it’s capable of going. If it can’t, it doesn’t matter how great your engine or fuel system is – you’ll quickly burn through the available oxygen and the engine will sputter back to idle. 

Function over jargon

Categorizing training in this way avoids the inaccuracies and pitfalls of focusing on the names of specific subsystems. Instead, you can focus on what they do and how they work. This helps us to understand the adaptations that we’re trying to target within all three subsystems. It’s also a much simpler mental model that reduces the technical knowledge needed to understand the primary drivers of an effective conditioning program. 

Limiting factors

A central principle of effective programming is focusing your efforts on the area that will produce the greatest ROI, or leveraging the biggest opportunity. This is obvious, but it’s also hard to consistently apply this principle because it requires a lot of self-discipline and a system to consistently identify what your largest leverage point is. 

You also must be willing to work on the things you’re the worst at – and do less of the things you’re already good at. Simple, but not easy. 

The easiest way to identify conditioning limiting factors is by asking a few simple questions: 

1 – Capacity or power limited? 

The power of your energy system is the rate at which it can produce work. More power means you can accelerate faster and ultimately produce more force over a given time. 

Capacity is about duration. It’s the size of your gas tank, not how big the engine is. 

In other words, can you go for a long time at a steady output but struggle to produce a lot of power, or do you struggle to go at a really fast clip for a short period of time? 

  • If you’re capacity limited, you need to spend more training time focusing on delivery methods.
  • If you’re power limited, you should focus on improving utilization. 
  • If you are equally capable of both, you should work on improving your delivery before transitioning to utilization methods. 

You can use our free assessment profile tool to identify if you are capacity or power limited based on what you’re training for (and much more). 

2 – Is your breathing limiting you? 

To assess for breathing limitations, ask yourself a simple question: 

  • Do you have chronic lower back, hip flexor, lat, and/or pec stiffness? 

If so, there is likely an element of breathing that is limiting your fitness. Posture and movement quality greatly influence your ability to move air (fuel) in and CO2 (exhaust) out. Even if you have decent conditioning outputs, if you are chronically stiff, your breathing will likely limit you from further progress. 

You can learn how to assess and improve your breathing. 

A real-world example: 5-mile run

A solid 5-mile run time requires a mix of delivery, utilization, and breathing adaptations. 

Most people who aren’t getting the times they want need to focus on more delivery or breathing adaptations. It’s a long event (even at a fast pace), so it’s unlikely that utilization – or the size of your engine – is the limiting factor unless you’re very detrained. 

However, if you can run a solid 5-mile time – and keep that same pace for another 5 miles – but can’t keep up on sprints or shorter events, you need to work on utilization. 

If your 5 mile run time sucks and your 400m sprint time is slow, you need to work on everything. It is possible to have multiple limiters. 

No matter what you’re training for, or what your limiting factor is, you should always have a mix of both styles of training in your plan:

  • Utilization-focused people should do some low intensity, long duration delivery type method
  • Delivery-focused people should do some high-intensity utilization style work, probably around (1x) per week.

You can read more about concurrent programming here. 

Specificity & Competing Demands

There are a few other factors to consider before putting together your conditioning program. 


You can’t become a good runner without running, nor can you become good at rucking without rucking. Yes, another obvious statement. But, let’s talk about why this is true and what role general fitness plays in being capable at many different tasks. 

Say you did all your delivery-focused (aerobic capacity) work on a bike. Would your rucking improve? Well, yes and no. All training modalities lead to systemic (general) and local (specific) adaptations. Biking would improve:

  • Your heart’s ability to move blood  
  • Capillary density and size
  • Mitochondrial density and power in work muscles

But, by biking and not rucking, your local tissues wouldn’t be stressed in the same way as biking. This would lead to a variety of missed adaptations:

  • Some muscles wouldn’t be stressed (say your calves and lower back), and thus wouldn’t see any adaptations
  • Local and systemic coordination of systems wouldn’t improve as effectively
  • Tissues wouldn’t adapt to handle carrying heavy loads on your back for long periods of time

So, general fitness adaptations can be pursued with non-specific training. But, over time you have to translate that general fitness into specific fitness. 


Tissues adapt specifically to the demands placed on them over months and years.

This is why changing posture takes so long and why interventions for improving movement have to be repeated several times per day and you then have to use that new motion in activities for them to ‘stick’. The older you are (physiologically and chronologically), the longer it will take to reshape tissues. 

Going back to our ruck vs bike example: if you spend a lot of time rucking, this will lead to tissue adaptations that make you more robust, or resistant to breakdown, on long rucks or repeated efforts day after day. Your tissues get used to the specific demands placed on them and become efficient at tolerating those forces with minimal recovery time. 

Specificity matters even within an activity. If you ruck on flat surfaces or relatively flat paths all the time and suddenly do a ruck with a huge climb and descent, you’ll feel surprisingly sore and beat up. Your tissues were adapted to rucking on flat ground, and when you introduce a large change like walking up and down steep hills, your tissues aren’t adapted to the new forces – leading to greater physiological damage and less efficiency. 

Technique, Pliability, and Stiffness

A large part of specific skill adaptations revolves around improvements in efficiency. Efficiency improvements come from improved technique and changes to tissues that improve the elastic component of any movement. 

If your running technique is poor and you’re overstriding, you’re overloading many tissues on each step. This leads to a lot of load on some tissues and not as much as you’d want on others. This overload might be more force than those tissues can handle while elastically stretching and rebounding, which reduces efficiency. 

On the other hand, if you increase stride frequency and distribute forces over your tissues more evenly, you could create a more efficient elastic rebound on each step, further increasing efficiency. 

In this way, technique and efficiency tend to go hand in hand with any skill and lead to specific tissue adaptations that lead to higher levels of output without a higher physiological cost. 

Let’s take a closer look at pliability and stiffness.

The person that squats 800 pounds doesn’t produce 4x more intramuscular force (even accounting for bigger muscles and therefore more contractile fibers) than the individual that squats 200. The 800-pound squatters’ tissues have adapted to having extremely heavy things crushing them and slowly become stiff enough to create an elastic response under those loads. This stiffness means that they probably can’t even squat to depth with 135 on the bar. Their tissues have become so stiff that they require hundreds of pounds of external load to create an elastic response. 

A good way to visualize this is by comparing a really big rubber band vs a tiny one. The big band requires far more force to stretch and rebound than the smaller one. A stiff human doesn’t lose the elasticity in their tissues, it just takes a lot more force to create that elastic response.  

This brings us to the topic of competing demands. 

Competing Demands

You can’t be great at everything. Competing demands, or adaptations that compete with each other, have to be considered.

For example, if you’re an amazingly efficient rucker, you’re probably a decent, but not a great runner. On the other hand, if you’re a really good runner, you’re probably decent at rucking. The general capacities necessary to be great at either will lead to being decent at the other. But, the specific adaptations necessary to be really good at one will necessarily reduce your potential in the other. 

To be an extremely good rucker, your tissues need to elastically deform and rebound during each step. This leads to higher outputs with the same internal physiological output. 

The elastic rebound is doing a decent chunk of the work – and this is free. Think of a rubber band stretching and being released over and over again.

The same is true if you’re a runner. But, your tissues can’t be simultaneously adapted to being pliable and elastic under just your bodyweight and while rucking with a 60-pound pack. 

Returning to our rubber band analogy: The really good rucker is the bigger, stiffer rubber band compared to the runner. 

In general, the closer to the extremes you get, the less capable you will be at everything else. 

If you’re working or training to be in SOF or any similar occupation, this won’t hold you back from being as capable as you need to be at everything. But, it does merit consideration when creating your training plan. You can’t overly specialize in anything without it negatively affecting other capabilities that you need to possess. 

Our Training App is designed to help you understand where you’re making trade-offs and where you should devote your training energy to improve weaknesses, based on your specific goal or career. This is important. There is no one-size-fits-all model that works for everyone. The specific ratio of physiological and skill-based capacities you need are specific to you and your goals. 

This brings us back to the concurrent training model, or why you always need to be training everything that matters. You should always do some amount of everything; only volume changes. Read more about concurrent training here. 

Energy System Methods 

We quantify conditioning outputs in two ways: power and capacity

The power of your energy system is the rate at which it can produce work. More power means you can accelerate faster and ultimately produce more force over a given time. 

Capacity is about duration. It’s the size of your gas tank, not how big the engine is. 

For this reason, our energy system development methods are split into three categories:

  • Capacity: This type of work emphasizes the delivery of oxygen to the tissues, utilization within them, and transport of waste out of the body over long periods of time.  
  • Power: This type of work emphasizes the utilization of all energy sources as quickly as possible.  
  • Blended: This type of work emphasizes both capacity and power by stressing both mechanisms. 

Below is a list of different energy systems methods in each category:

Energy system methods of conditioning for special operations selection

Wrap Up

The conditioning model presented in this article is meant to simplify the model you use to think about organizing your conditioning training for special operations selection prep over time. Combined with our free Profile Assessment Tool and the other articles on this site, you should easily be able to craft an effective program based on your specific needs. If you are seeking professional programming help, the Building the Elite App provides individualized training programs based on your individual goals (including selection preparation for several programs), timeline, and capabilities.

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