What is the Difference Between Anaerobic and Aerobic Conditioning?
Written by Dave Thomas
The following is an excerpt from our Performance360 Fully Certified Coach (FCC) program.
On our May podcast, one of the questions we answered was the difference between Anaerobic and Aerobic conditioning, how to train each, and why each are beneficial. Today, we provide the written form of that answer at greater depth.
There are three points I would like to make clear before I begin.
Point number one. Understanding the difference between energy systems is a critical part of your success as an athlete and coach if your aim is to target very specific conditioning goals or competitive outcomes for athletes and coaches. It is not as critical if you are a Gen Pop gym goer who just wants to show up and get in great all around shape. Wherever you land on the spectrum, some knowledge of which energy system you are in can help you understand why you might be hitting a plateau, what to include more of for goals X, Y and Z, or how to get you better at something where you may be lacking.
Point number two. “Cardio” and conditioning are not the same thing. There is a major difference between going for a thirty minute jog, and performing mixed modal work for ten minutes at a high pace. Both can be effective through completely different mechanisms. In my personal opinion, cardio is thoughtless sweating to achieve caloric burn (nothing wrong with that, I do it). Conditioning is purposeful metabolic training to achieve a fitness outcome.
Point number three. Very rarely are you in one fuel system. If you perform functional fitness as your brand of exercise, you’re bouncing around multiple fuel systems with most conditioning formats. Some exceptions do exist which we’ll review (i.e. 500m row), but this is the precise reason why I think getting caught up in the specifics can be a fruitless endeavor. We can talk all day about benefits and mechanisms of both aerobic and anaerobic work, but most of the time, we’re not exclusive with our energy systems. We’re slutting around.
The best way to understand energy systems is to relate it to intensity, as that is the primary variable that decides which system you are in. Think about intensity that moves along a spectrum. On the far left hand side, we have longer duration cardio at low intensity. On the far right hand side, a maximum effort event that’s high intensity, short duration. Most days, we operate as some blend of the middle ground.
This is, hopefully, an obvious generalization meant to illustrate a basic understanding of how intensity effects energy system training. It is not exact, but it is close enough to the mark to get you started.
Let’s take a little bit of a closer look at each.
Anaerobic System: “Mustang”
Main Goal: Performance
Intensity: High to max
Duration: A few seconds to a few minutes.
Examples: 500m row, 5-10 minute density circuit, Timed IWT, 800m run
Who is It For: Athletes with competitive fitness goals
What Does It Work: Your ability to go at your maximum pace for longer, timed workouts, horsepower and “kick”
James Fitzgerald has a brilliant way of illustrating fuel systems with his “Gain, Pain, and Sustain” nomenclature. It’s brilliant and I love it, but I don’t necessarily like pain to be the objective. Our inspired version of that trio is “Feat, Compete, Repeat” so we dub the anaerobic energy system “The Compete System” due to it’s high intense nature, and puts is in a position of discomfort where we must compete with ourselves or others in order to sustain it.
Think of the anaerobic system like a Mustang. High speed, not great duration or gas mileage. The level of intensity is not sustainable past a few minutes. I also want you to take a look at the examples listed above. You will notice that the time frame for anaerobic circuits is 5 – 10 minutes. Now, by all textual definitions ten minutes would automatically place you into aerobic work, and that is partially true. But remember point number three in the introduction, we are almost never exclusively in one system, and in a five to ten minute circuit that asks the athlete to go as hard as possible, you will skew highly anaerobic. That’s what’s important to know.
The primary source of this fuel comes from glycogen, our bodies stored carbohydrates from food. This kind of intensity of training ultimately results in a hydrogen build up in the blood, which leads to a decrease in power, and muscle fatigue.
Here’s a summary of how all of that nonsense occurs. It’s technical and boring, so feel free to skip it.
- Stored glycogen is converted to glucose, which is then broken down to make ATP, the molecule we use as energy for all physical activity.
- This chemical reaction results in creation of pyruvate and hydrogen, which causes the working muscles to quickly become very acidic at high intensities. Hydrogen is a pesky asshole that wants you to fail.
- Because sufficient oxygen is not present, pyruvate binds with hydrogen to create lactate (this is not lactic acid), so that it can be removed from the muscle cell, protecting it from becoming too acidic and leading to muscle failure.
- Lactate can then be re-shuttled back to muscles or the liver to undergo chemical reactions that are able to use it for further energy production.
- Without lactate production, we would burn out from the hydrogen build-up a lot sooner. Lactate is not bad like it has long been portrayed.
Benefit: Improved Lactate Threshold
Lactate has long been falsely labeled as a metabolic waste product of anaerobic training that would interfere with performance and cause next day muscle soreness (recently been attributed to inflammation), so coaches, stop saying soreness is lactic acid. It’s not. People a lot smarter than I have not yet managed to agree on lactate’s exact role in fitness, but we know it is a needed byproduct of the anaerobic system. When we “compete” our body produces more lactate to help us try and sustain effort and to try and keep pace with ATP production, as we just learned. In doing so, if we do not slow our intensity on our own, we will ultimately reach a lactate level than our body can handle.
This is known as reaching Lactate Threshold. It is a different point for every athlete, but once at threshold, highly acidic hydrogen begins to build up in the blood faster than we can buffer it out, and once accumulation begins to outpace removal, we hit failure. Our bloodstream cannot perform physically with this level of blood acid, so it simply stops or slows muscle contraction to all ourselves to remove it.
Lactate Threshold is the point during exercise of increasing intensity where lactate clearance is no longer able to keep up with lactate production. Hydrogen wins, fatigue ensues, and you feel like offing yourself.
In looking at competition, the reason that an athlete has the superior ability to record a faster time for a short distance race or workout event is attributed to two possible reasons:
- The lactate threshold is trained or genetically hard wired to occur at a higher percentage of one’s capacity. Through laboratory testing, we know that high performing athletes show less blood lactate levels at high levels of exertion, meaning they are able to buffer the lactate/hydrogen from the blood at faster rates, and not have acidosis interfere with muscle contraction as much as their counterparts.
- The athlete’s ability to remove lactate more efficiently and convert it to energy (as glucose) is faster than their counterpart. As a result, they never hit the contraction failure or fatigue point that others do.
One’s ceiling for this is influenced by genetics (why the same freaks always seem to win), but it can also be improved through training this system. Specificity 101.
There are varying viewpoints on what consists of Lactate Threshold. At the end of the day, what this is, no matter how you choose to label it is metabolic stress placed on the body and our increased response to that stress through training adaption.
Thus, through proper training and intensity dosing, we’re able to to improve our Maximal Metabolic Stress Sustainability (MMSS), a term coined by the renown Dr. Mel Siff.
We’re able to go harder, longer.
Best Zone to Improve Your Threshold
In order to develop and train in energy system tests like the 500m row, 1k row, 800m run and 1 mile run, we want to be repeatable in our efforts, but still hard enough to get benefits. This is usually around 90-95% of effort. If an athlete has a 2:45 800m sprint PR and is training to improve it, they are best served at a 2:53 – 3:01 pacing and repeatable efforts of it within a single training session.
Benefit: Improved Peripheral Muscle Adaptation
Local Muscle Fatigue is the acute fatigue we experience during a training session in the working muscles of a session, and may occur from decreased blood flow to working muscles. At higher reps of muscle contraction, blood flow becomes restricted due to compression of blood cells by contracting muscles, and oxygen to the working muscles becomes cut off. The working muscles quite literally choke off their own supply of recovery, like some sort of auto-eroticism gone wrong. Or something.
Anaerobic system training in particular is very effective at improving our local muscular endurance and resistance to local muscle fatigue because it causes peripheral adaptation of the muscles, which is to say it trains them to be able to operate better without oxygen (anaerobically). Put another way, our endurance is improved because of the muscle’s efficiency in an anaerobic state, not “cardiovascular benefits”.
This anaerobic training has also been shown to greatly improve and carry over to aerobic demands, as well.
Drawback: Elevated Cortisol
It can be very easy to get addicted to the feeling of all out exhaustion and mistakenly making a linear link between exertion effort and results. You don’t have to try as hard as you can every day to get get results. In fact, you shouldn’t. Stressful training can cause chronically elevated levels of cortisol, which can create muscle catabolism, preserve body fat, and slow our metabolism. This can usually be mitigated with proper nutrition and proper intensity dosing throughout the week, but the training benefits of training near Lactate Threshold also come with some metabolic drawbacks if mismanaged.
Train often. Test rarely.
Drawback: Questionably Needed
Maximal and near-maximal intensity for short duration is good to keep our body adapting to new stimulus, and it’s a very important part of training for athlete’s who compete either in the gym or outside of it, but it’s not that great of a choice for Gen Pop athletes. It’s not long enough in duration to have a major effect on body composition (we primarly burn up stored carbohydrates, not body fat) and as mentioned above, it can be taxing on the body.
The takeaway for anaerobic conditioning is that it’s extremely beneficial for your competitive fitness, horsepower, and kick in a race or workout. It’s not ideal to be performed daily.
Aerobic System: “Prius”
Main Goal: Fitness
Intensity: Low to moderate
Duration: Longer, ~10 – 30 minutes
Examples: 15-20 minute Tier 2, 3 mile run, 1000m row
Who is It For: Everyone
What Does It Work: Your ability to go at sub-maximal for longer, your overall “fitness”, calorie burning, cardiovascular health
We dub this energy system “The Repeat System” due to its low intense nature that we can repeat over time relatively easily. Think of this like a Prius. Lower power, yet longer duration that can go on well past the Mustang. This is our slowest form of ATP energy creation, but we have a huge supply of it because we use carbs, fats and sometimes protein to make it.
Because oxygen is present, there is no hydrogen build up, thus we do not become overly acidic and can continue for longer. Power never peaks in this energy system and we never reach or train near our Lactate Threshold.
- Ideal for Beginners – All beginners must focus more on aerobic endurance than anaerobic endurance while they build their foundation and tolerance to stress. To go about it any other way would be nonsensical. This I am passionate about.
- Cardiovascular Benefits – Aerobic training has a scientifically proven positive effect on blood pressure and blood lipid levels, reducing the likelihood of coronary disease.
- Oxidizing Body Fat – Aerobic work can also be beneficial at maintaining body fat balance. By definition, we are in the oxidative pathways which means we will be mobilizing stored fatty acids as fuel. Remember that anaerobic training primarily uses stored carbohydrates in the body. Intensity does have an impact on fat burning, but so does duration. It’s good to have balance.
- Lactate Buffering – It is important to understand that training at threshold does not necessarily improve threshold. Think about this along the same lines of how a 1R max doesn’t necessarily improve your strength. It simply reveals it. Lactate is mainly produced by Type-II muscle fibers which are highly glycolytic, however lactate is mainly cleared by Type-I fibers that have a higher mitochondrial capacity. Therefore, to get better at clearing lactate, even in the format of a brutally intense short duration circuit, we need to have trained Type-I fibers.
- Builds Muscle Endurance – A development that is crucial for beginners to establish on a low intensity setting, but also very important for advanced folks to return to often, as well. You lose muscle endurance if you don’t train it.
- Endurance Specificity – If you are training for endurance, you need to train endurance. Like anything, specificity is king.
- Sustainability – 20 minute mixed modal conditioning work at low to moderate intensity can be performed daily without putting your body into a stressful, catabolic state.
As we mentioned in the introduction of this article, our version of Aerobic System is not what modern fitness has taught us. While we don’t find much wrong with going on a nice, long run, we are mainly referring to mixed modal circuit training in the range of 15 to 30 minutes.
If long duration aerobic work (attention, runners) is the primary form of exercise chosen, the drawbacks of muscle catabolism, body composition plateaus, and reduced strength and power will occur. You also won’t see yourself turn into a high powered athlete if aerobic work comprises your only form of conditioning.
Performance. Shorter in duration, higher in intensity. Not sustainable past a few minutes of intense effort. Helps to improve our ability to go as hard as we can for as long we can. Necessity for all around fitness is debatable, but very needed training for certain high-level athletes who have competitive goals.
Fitness. Longer in duration, lower in intensity. Very sustainable past a few minutes of moderate effort. Less targeted than anaerobic training, helps to improve our all around fitness and longer term endurance. Typically a higher caloric expenditure and more positive health markers.
In the old tale of The Tortoise and The Hare, the aerobic system is the tortoise and the anaerobic system is the Hare. That day, the race happened to be longer so the tortoise won, but not all fitness is so. It depends on your race and goals.
In Part II of this article, we will take a look at different conditioning examples and breakdown their energy systems and benefits. Understand energy systems and you’ll better understand your limitations and how to better reach your fitness goals.
Coaches, our FCC certification will be open to the public for the first time in our gym’s history this November. To join our invitation list for when Early Bird Pricing goes live, visit the official FCC page.
Siff, Mel Cunningham. “Strength and the Muscular System.” Supertraining. Denver: Supertraining Institute, 2003. 216. Print.
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Fitzgerald, James. “Energy Systems Training.” Opex Fitness. OPEX, 14 Jan. 2017. Web. 03 Feb. 2017.
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Withers RT, Sherman WM, Clark DG, Esselbach PC, Nolan SR, Mackay MH, and Brinkman M (1991). Muscle metabolism during 30, 60 and 90s of maximal cycling on an airbraked ergometer. European Journal of Applied Physiology, 63: 354 – 362
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