What is Fitness?
Can you define fitness? It’s not as easy as it sounds. Sure, dictionaries try, but they always seem to miss the mark:
fitness | ˈfitnis |
noun:
The condition of being physically fit and healthy: disease and lack of fitness are closely related | [ as modifier ] : a fitness test.
The quality of being suitable to fulfill a particular role or task: he had a year in which to establish his fitness for the office.
Biology: an organism’s ability to survive and reproduce in a particular environment: if sharp teeth increase fitness, genes causing sharp teeth will increase in frequency.
But we believe fitness goes beyond what any dictionary can capture. It’s not just about how you look or feel—those are important, sure, but they're subjective. We need something more concrete, something we can measure, observe, and repeat. That's how we track improvement. You can see how fit you are in relation to any physical task, and more importantly, where you need to improve.
To truly understand fitness, we rely on three core models that work together to paint a complete picture of what it means to be fit. Let's break them down.
Three Models of Fitness
These models, when combined, give us a broad and useful definition of fitness. Understanding these can reshape the way you think about your own health and progress.
1. The Ten General Physical Skills of Fitness
To be truly fit, you need a well-rounded foundation across these ten skills:
Cardiovascular/Respiratory Endurance – Your body’s ability to deliver oxygen efficiently.
Stamina – The ability to store, deliver, and use energy.
Strength – How well your muscles apply force.
Flexibility – Maximizing range of motion at any joint.
Power – Applying maximum force in the shortest time.
Speed – Reducing the time between repeated movements.
Coordination – Combining multiple movements into one.
Agility – Transitioning quickly from one movement to another.
Balance – Controlling the body’s center of gravity.
Accuracy – Controlling movement in a specific direction or intensity.
How do you stack up in each of these areas? Weakness in even one of these can hold you back from being your fittest self. Take a moment to think about where you might need more work.
2. The Hopper
Imagine a hopper full of random physical challenges—from rock climbing to grocery bag carrying to sprinting. If we pulled out a task at random, could you handle it? A truly fit person could. Fitness isn’t just about excelling at a single activity; it’s about being capable, strong, and competent across any task life throws at you.
What task would you fear if it popped up? Is your training improving your overall capacity to handle life’s random challenges?
3. The Energy Pathways
Your body operates on three energy systems that fuel different activities. A fit person is proficient in all three.
Phosphagen System: Provides energy for short bursts of up to 10 seconds, like a max-effort lift or sprint.
Glycolytic System: Fuels activities lasting up to 2 minutes, like a 400m dash or circuit training.
Oxidative System: Powers long-duration activities like a 5K run or marathon, kicking in after about 5 minutes of continuous effort.
When was the last time you trained in all three systems? If you only ever go for long runs or avoid sprinting or lifting heavy, you're likely leaving gaps in your fitness.
The Full Picture of Fitness
By combining these three models—the 10 physical skills, the hopper concept, and the energy pathways—you get a complete picture of fitness. It’s not enough to be great at one thing or to work only in one energy system. True fitness is about being ready for anything and having the well-rounded skills to handle it.
If your idea of fitness is based solely on running marathons or cycling long distances, you're missing out. Those activities may hit the oxidative energy system, but how are you doing on strength? Power? Flexibility? You might struggle in a hopper test or be lacking proficiency in the glycolytic or phosphagen pathways.
To set a higher standard for yourself, you’ve got to train all areas of fitness. You can’t just focus on what’s comfortable or easy—fitness is about facing those weaknesses head-on and becoming the most capable, well-rounded version of yourself.
No matter where you are today, you can start improving. Look at your fitness across these models and identify where you're weakest. Whether it's strength, endurance, or skill, taking small steps today will set you on the path to becoming your fittest self tomorrow.
