The Best Science-Based Cardio Routines For Fat Loss And Performance - backup

One of the biggest result-killing mistakes most people trying to get shredded for summer will make? 

Doing random things in the gym simply because they "feel hard", just hoping it'll lead to results. 

This is especially true when it comes to cardio, as very few people have any understanding of the energy systems, or even think about the specific outcomes they want to achieve from doing a specific type of cardio.  

(This is also true when it comes to resistance training, but read our Hypertrophy Guide for more on that.) 

So today, we’re taking a deep dive into the how to program smarter, more effective cardio. Whether your goal is fat loss, performance, or general conditioning, the knowledge in this blog will level up your results.


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 store? Requires your body to produce energy. 

→ Even the “stress response”  to a mental stressor causes energy to be mobilized (and then sometimes re-stored).

You get the idea. 

Every action we take requires our body to first create energy for said actions.

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

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


Your body can produce energy (ATP) in two different ways: 

1: AEROBICALLY (meaning with oxygen): Using your Aerobic Energy System 

2: ANAEROBICALLY (meaning without oxygen): Using your 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.

Now, let's dig into the science behind how (and why) to program for each energy system, depending if your goal is fat loss, performance, or conditioning.


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 (or 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

→ Protein 

...can all 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)

This means 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 breh!"

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 (a.k.a rest and digest) state quicker after training - translating to better recovery and more progress.

Why everyone can benefit from aerobic training:

→ It develops your cardiovascular system, decreasing the risk of cardiovascular disease. 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.


To summarize:  

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

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

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


When programming aerobic work, we can use two different styles of training: 

1. Cyclical 

2. Mixed-Modal

CYCLICAL TRAINING: 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 TRAINING: 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:

1. Getting clients more core work, upper back work, unilateral work, etc.

2. Improving their aerobic system and increasing fat loss 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 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.

Why not everyone needs to (or should) do much lactic system specific conditioning:

→ 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 leave you feeling absolutely smashed, 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.


To summarize:

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

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


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 you do want to be able to achieve a similar level of power output across all of our sets for the day. 

→ So don't completely destroy yourself on the first few sets, because power output will 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.


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.) 

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.  

You use this energy system often when lifting weights. 

Why everyone can benefit from some alactic training: 

→ 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).


To summarize:

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

2. Phosphocreatine is the primary fuel source here.


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's how to start programming smarter, more effective cardio; whether your goal is fat loss, conditioning, or performance.

These are the same science-backed strategies we implement with our online clients undergoing the physique transformation process.  

If you're ready to be coached 1-1 by our team to your best physique ever, click here now to apply for online coaching with our team.

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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