In this blog, we’re taking a deeper dive into the energy systems and exploring what it truly means to be conditioned.
When we talk about being conditioned, we’re referring to your body’s ability to meet the physical demands placed on it. While this can be highly specific to an athlete’s sport, we’re looking at it through the lens of the everyday member—someone who wants to feel strong, move well, and live better.
Conditioning in the Big Picture
Greg Glassman’s Hierarchy of the Development of an Athlete aims to build off of the foundations including quality sleep/ mental health & nutrition and places metabolic conditioning just above it—before training for peak strength, skill, or sport-specific practice. That’s because energy system development forms the foundation for everything else in fitness.
At Pursuit, our mission is to build a hedge against chronic disease—and that starts with making sure you’re conditioned for whatever life throws at you outside the gym, too.
What Conditioning Includes
Conditioning isn’t just the work you put in at the gym. It includes:
- Practice and movement quality
- Sleep and recovery
- How efficiently your body produces and utilizes energy
For this blog, we’re focusing specifically on training the body’s energy systems—starting this week with the aerobic system—to build what many would call a “conditioned athlete.”
What the Experts Say
In Ultimate MMA Conditioning, Joel Jamieson defines conditioning as:
“The result of how well the systems of your body are able to create energy your muscles need to perform the skills of MMA throughout a fight.”
While life is obviously very different from a cage fight, the energy demands required for endurance, power, and recovery are surprisingly similar. Most people benefit from training across the energy continuum, which lies between explosive power output and long-duration endurance work.
The Two Sides of Conditioning
There are six components of conditioning (see image below), but they all boil down to two key aspects:
1. Energy Production
Our muscles run on a molecule called ATP (adenosine triphosphate). When ATP is broken down into ADP (adenosine diphosphate) and Pi (inorganic phosphate), energy is released to power movement.
Joel Jamieson calls ATP the “energy currency” of the body. Everything you eat—fats, carbs, proteins—is eventually broken down to either produce ATP directly or stored to be used later.
2. Energy Utilization
It’s not just about how much ATP you can produce—it’s how efficiently you use it. This is where movement mechanics and experience come into play.
Better movement = less energy wasted.
Over time, this leads to greater efficiency and resilience.
That’s something I’ve always appreciated about the CrossFit methodology—there’s always something to improve and refine.
The Three Energy Systems
Your body uses three energy systems to create ATP:
- Phosphagen (ATP-PC) – short bursts (e.g., sprinting, heavy lifting)
- Glycolytic – moderate duration, higher intensity
- Aerobic – long duration, lower intensity
Today, we’re focusing solely on the aerobic system as we build on last week’s discussion.
The Aerobic Energy System: The Engine of Everyday Life
The aerobic system uses oxygen to create ATP and is responsible for sustained, long-term energy production. It’s the only system that can break down both fats and carbohydrates for fuel, making it essential for daily life.
This system fuels:
- Walking, daily chores
- Recovery between intense efforts
- Long workouts or hikes
- Basic human function (yes, even sleeping)
The Byproducts
The byproducts of aerobic metabolism are carbon dioxide and water. Because of this, aerobic energy production is limited by:
- Your cardiovascular system (how well you transport oxygen)
- Muscle oxygen utilization
- Enzyme and substrate availability
These factors can all be trained—meaning you can increase your ability to produce energy aerobically, improving your overall work capacity.
Why It Matters
Joel Jamieson explains that a strong aerobic system doesn’t just help endurance—it also supports your anaerobic systems. In other words, a better aerobic base helps you recover faster, push harder, and raise your overall training threshold.
This is why aerobic development is crucial, even for power athletes or general population members. It’s the refueling engine behind all your effort.
Final Thoughts
Conditioning isn’t just about going harder—it’s about being smarter with your training, developing the engine that powers you through your day, and setting yourself up for long-term performance and health.
Whether you’re chasing performance or just chasing your kids—this stuff matters.
Stay tuned for next week’s post as we dive into the three Key components of Aerobic Energy Production and how to apply aerobic based training methods in your program 🙂
– The Pursuit Team
References
- Jamieson, Joel.
Ultimate MMA Conditioning. 2nd Edition.- This is your primary reference, especially for the quote and the concept that the aerobic system supports the anaerobic systems.
- https://www.8weeksout.com
- Kenney, W. Larry, Wilmore, Jack H., & Costill, David L.
Physiology of Sport and Exercise. 6th Edition. Human Kinetics, 2015.- A comprehensive resource on energy systems, ATP production, and cardiorespiratory adaptations.
- McArdle, William D., Katch, Frank I., & Katch, Victor L.
Exercise Physiology: Nutrition, Energy, and Human Performance. 8th Edition.- Widely used in academic exercise science programs; covers energy systems, metabolic pathways, and training adaptations.
- Glassman, Greg.
What is Fitness? CrossFit Journal, October 2002.- Introduces the Hierarchy of Development and CrossFit’s definition of fitness.
- https://journal.crossfit.com/article/what-is-fitness
- NSCA – National Strength and Conditioning Association
Essentials of Strength Training and Conditioning.- Offers in-depth information on training principles, energy systems, and program design.
- https://www.nsca.com
- Bompa, Tudor O., & Haff, G. Gregory.
Periodization: Theory and Methodology of Training.- Excellent source on training adaptation and how aerobic conditioning fits into long-term development.
