How To Program The Most Effective Cardio For Your Clients [Energy Systems 101]


One of the biggest client-result-killing mistakes most coaches make?

Programming random things simply because they "feel hard", just hoping it'll lead to client results.

This is especially true when it comes to cardio, as very few coaches have any understanding of the energy systems, or even think about the specific outcomes they want their clients to achieve from their cardio prescriptions. 

(Also true when it comes to resistance training, but I’ve already created a series of blogs to help you out in this regard. Check them out: 1, 2, 3)

So today, we’re taking a deep dive into the energy systems. You'll learn how to program smarter, more goal specific cardio for your clients, and help them achieve leaner, stronger, and better conditioned bodies.


Everything you do eventually comes back to your body’s ability to produce energy.

—> Want greater power output in the gym? That requires more energy.

—> Walking though the stores? Requires your body to produce energy.

—> Even the “stress response”  to a mental stressor causes energy to be mobilized (and then sometimes re-stored). This process takes energy.

You get the idea. Every action we take requires our body to first create energy for out actions.

Basically, your body uses the food you take in, and converts it to ATP, the body's "energy currency".

Without adequate levels of this energy currency, we won't be able to perform as desired. So ATP/energy currency is constantly being created by...

The Energy Systems

Basically, your body can produce energy (ATP) in two different ways:

1. Aerobically (with oxygen), using the Aerobic Energy System

2. Anaerobically (without oxygen), using the Anaerobic Energy System(s)

Each energy system has a different capacity and duration that it can continue to produce energy. As a result of this, each energy system also relies on different fuel source.

So, your energy systems essentially provide the fuel for different activities - be it an explosive round of squats, or a slow walk on an incline treadmill. 

Now, you've probably noticed that your ability to exert yourself strenuously fades rather quickly. This is (partially) because there is a trade-off between how fast your body can produce energy, and the level of power output that can be maintained.

The longer the duration of an activity, the lower the amount of power you'll be able to output will be (to an extent), because your energy systems can't keep up with the ATP production demands required to keep power high.

All three of these energy systems are always working, but the primary system at work will depend on the power output & duration of an activity.

With me so far? Dope. 

Let's dive into each specific energy system.

The Aerobic System

As you can see from the graphic above, your aerobic system provides the majority of the energy for anything longer than 60 seconds.

Really, your aerobic system is crazy important. It's responsible for creating the ATP necessary to fuel the majority of your life. The aerobic system is the most important energy system for you and your clients to develop.

Because your aerobic system plays such a key role in... well, keeping you alive... it's very adaptable, and can break down many different macros as fuel sources. Carbs, fats, and even protein can be converted to ATP by your aerobic system.

This system has a very large energy supply available, and thus is capable of producing ATP to fuel HOURS of work at a sustainable pace. But as we discussed earlier, the fact that the aerobic system can generate fuel for such long periods of time also means that it has the lowest level of power output of all of the energy systems.

Your aerobic system is also what drives recovery from anaerobic bouts... meaning that your aerobic system is what helps you recover between short, intense bouts of effort (e.g. a max effort set of squats). So having higher levels of aerobic fitness means you'll be able to recover faster between short periods of intense effort.

So while the common thinking is...

"Cardio kills your gainz"

The reality is, a strong aerobic system will allow you to recover quicker and more fully between sets in the gym, meaning you'll be able to put forth a better effort (and build more muscle) during each set.

Having a higher level of aerobic fitness also allows your autonomic nervous system to get back into a parasympathetic (rest and digest) state quicker after training - translating to better recovery and more progress.

Everyone can benefit from some aerobic training. Because...

—> It develops your cardiovascular system, decreasing the risk of cardiovascular disease in your clients. Ditto for high blood pressure.

—> Your heart is also better able to deliver oxygen to muscles during training.

—> Your body is better able to move more blood, quicker throughout the body, keeping cells and tissues healthier. Just like any muscle, the heart actually grows bigger to support improved functioning. 

—> In the context of programming cardio for muscle gain/performance, it can indirectly leads to better recovery, and more lean muscle from your resistance training.

—> In the context of programming cardio for fat loss, aerobic work generally makes the most sense. It actually improves your recovery & your body's ability to manage stress during a time when "recovery resources" are already limited - whereas programming more intense modalities of cardio can create more stress that your body must spend it's limited recovery resources on.

Aerobic System Summary:

So in a nutshell...

—> Your aerobic system is the primary energy system creating ATP for longer duration activities, done at a sustainable pace.

—> Your aerobic system uses a variety of fuels - carbs, fats, and (if needed) protein + oxygen to generate ATP. 

—> Your aerobic system is the most important energy system. Everyone can benefit from training it.

Aerobic Sytem Training:

When programming aerobic work, we can use two different styles of training: cyclical or mixed-modal.

—> Cyclical - Here, we're programming a single movement/piece of equipment - rower, airbike, sled drag, jogging, etc.

When programming aerobic work, the goal is working at a sustainable pace, and maintaining performance across sets and weeks. We usually progress this across weeks by adding time/distance to the work sets.

For example, a cyclical aerobic progression could look something like:

Rowing Machine

- Week 1: 5x1000 @ 2:00/500m pace (2 mins rest)

- Week 2: 5x1200m @ 2:00/500m pace (2 mins rest)

- Week 3: 4x1500m @ 2:00/500m pace (2 mins rest)

- Week 4: 3x2000m @ 2:00/500m pace (2 mins rest)

The total distance stays nearly the same across weeks - our primary means of progression here is increasing the distance per set, while maintaining the same pace.

—> Mixed Modal - This is generally a circuit style of training, involving multiple exercises and modalities. This is one of my favorite ways to program finishers, as we can often kill two birds with one stone - getting clients more core work, upper back work, unilateral work, etc, and improving their aerobic system at the same time.

For example, a mixed modal aerobic progression could look something like:

AMRAP (As Many Rounds As Possible)

- Week 1: 5 mins of - Rowing Machine x10 Cals / Push-Up x10-20 / Farmer's Walk x50m 

- Week 2: 6 mins of - Rowing Machine x10 Cals / Push-Up x10-20 / Farmer's Walk x50m 

- Week 3: 7 mins of - Rowing Machine x10 Cals / Push-Up x10-20 / Farmer's Walk x50m 

- Week 4: 8 mins of - Rowing Machine x10 Cals / Push-Up x10-20 / Farmer's Walk x50m 

With our goal being to sustain pace as total time/distance increases, we should be adding sets weekly here.

The Anaerobic-Lactic System

The lactic system helps provide energy for activity up to about 30-40 seconds in duration.

When you're burning through ATP faster than your aerobic system can handle, your body starts using lactate as a fuel to start converting glucose into ATP.

We don't need to get into the specifics of anaerobic metabolism here. You just need to know that lactate + glucose = quicker ATP production/the ability to produce more force.

Unlike with the aerobic system, oxygen is not being used here.

Glucose is the primary fuel source for the lactic system, which is why our ability to produce power often suffers on a low carb diet. This is also why I generally prefer a higher carb nutrition approach for online clients looking to build maximal lean muscle, or optimize performance.

Not every needs (or should) do much lactic system specific conditioning. Because...

—> Anaerobic-lactic training creates a huge amount of stress on the system, and pushes the nervous system into "fight-or-flight" mode. While not always a bad thing (the formula for growth is STRESS + recovery = adaptation), implementing too much anaerobic-lactic work has the ability to smash your clients and SLOW recovery.

—> For clients who's goals are simply to look good & be healthy, this style of training often isn't needed. 

—> In the context of programming cardio for fat loss, although it does allow for less time spent for calorie burned, we have to carefully consider the huge amount of stress we're adding to our clients "recovery debt". If we're simply looking to burn more calories, less stressful modalities of cardio make sense.

—> In the context of programming cardio for muscle gain/performance, for clients that need to be able to produce high levels of force for relatively short durations (e.g. CrossFitters), this style of training is helpful.

Anaerobic-Lactic System Summary:

—> Your lactic system provides energy for shorter, unsustainable bursts of effort (usually up to 40 seconds).

—> Glucose is the primary fuel source here, oxygen is not being utilized.

Anaerobic-Lactic System Training:

Training the lactic system should feel brutal. That's why OPEX nicknamed this energy system's training method "Pain" after all. The effort/power output in a set should be high and unsustainable for more than 40-60 sec, but we do want to be able to achieve a similar level of power output across all of our sets for the day. So we don't want to completely destroy ourselves on the first few sets, and then see power output fall off by a large amount during the later half of the training session.

For example, a lactic training progression could look like:

Assault Bike

Week 1 - 20 sec near all-out every 3.5 mins x 6.

- Week 2 - 25 seconds near all out every 4 minutes x 5.

- Week 3 - 30 seconds near all out every 5 minutes x 4.

- Week 4 - 45 seconds near all out every 6 minutes x 2.

Set duration across weeks increases, but total number of sets decreases. Again, we should see similar power output, RPM, calories burned, etc., across the course of sets. A big drop off in performance from the first set to the last set in the training day indicates that you're going too hard in the early sets, and won't acquire the adaptations we're chasing here.

The Anaerobic-Alactic System

Your alactic system is the most powerful of the three energy systems, but also has the shortest duration, typically lasting 10-20 seconds.

The alactic system is able to produce lots of power, quickly, because the pathway to convert phosphocreatine (the fuel source of the alactic system) is much simpler than the chemical process for creating ATP with the other two energy systems. (This is also why supplementing with creatine is helpful - it gives this energy system more fuel.)

The problem is, the alactic system is not as adaptable as the other two systems when it comes to fuel sources, and our supplies of phosphocreatine are drained quickly.

Similar to the lactic system, oxygen is not being utilized to create energy here. 

Clients will use this energy system often during resistance training.

Everyone can benefit from some alactic training. Because...

—> In its most commonly programmed form, alactic training is lifting weights. As a reader of this blog, I doubt I even need to tell you the many benefits of lifting weights. Things like better nutrient partitioning, a higher your metabolic rate, functional strength, healthy tendons, increases bone density, and aesthetics.

—> In the context of programming cardio for fat loss, this style of training doesn't make much sense. A smart resistance training program is a huge part of building a great physique, but cardio-specific alactic programming involves very short bouts, in a relatively low volume. 

—> More advanced clients can also benefit from explosive alactic training outside of just lifting weights (e.g. short, all-out assault bike sprints or sled pushes).

Anaerobic-Alactic System Summary:

—> This is the most powerful energy system, but it's limited to very short durations.

—> Phosphocreatine is the primary fuel source here.

Anaerobic-Alactic System Training:

Again, this most often takes the form of well programmed resistance training. 

That said, we can also program things like assault bike sprints, sled push, kettlebell swings, squat jumps, etc. here. Generally for a work period of 8-15 seconds, followed by 1-3 minutes rest.

For example, an alactic training progression could look like:

Sled Sprints

- Week 1: 8 sec all out x 12. 90 sec rest.

- Week 2: 10 sec all out x 10. 90 sec rest.

- Week 3: 12 sec all out x 8. 2 min rest.

- Week 4: 15 sec all out x6. 2.5 min rest.

And that is how we program smart, goal specific cardio for our clients, and help them achieve superior results.

If you're ready to experience a program 100% customized and goal-specific to you as an individual, and build your leanest, strongest body ever - click here now to apply for online coaching with me.

About The Author

Jeremiah Bair is a certified nutrition coach, strength coach, and owner of the online coaching business Bairfit. Check out his Podcast and Instagram for more educational content.

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