What is Fitness? Part 5: Fit = Physical Fitness

In this blog series, I am exploring the ways I think about and define fitness.  Here are the previous articles:


Physical Fitness

“Fit” is the realm of bodily health and physical fitness.  This is pretty much what most people are talking about when they use the term “fitness”.  This is what we endeavor to achieve by  committing to exercise programs and nutrition plans.

There are a lot of components to physical fitness, a lot of systems in the body that we are trying to change.  The first that come to mind might be your heart, lungs, and circulatory system.  You know you’ll be improving those when you do cardio.  The changes to muscle, bones, and connective tissues that occur through lifting weights are also well known.  But, have you thought about your brain and nerves, mitochondria, and the endocrine system?

Human beings are complicated organisms, but I have a simplified way to communicate about physical fitness based on three somewhat-overlapping spheres: Endurance, Strength, and Movement Ability.


Endurance is your ability to last.  There are different kinds of endurance.  Muscles, bones, joints, and connective tissues need to be able to put up with extended periods of load and challenge, like the repeated impacts of running.  Your lungs need to be able to expel CO2, take in fresh air, and your heart needs to be able to pump that fresh oxygenated blood supply throughout your body.  The mitochondria of your cells need to be able to supply the energy to continue all those muscular contractions.  There is also the endurance of your mind, which needs to be able to focus on a task and grind it out until it’s done.

So, there are several aspects to endurance: the cardiorespiratory endurance, the muscular endurance, the mental endurance.  Endurance can also be looked at as an interplay between Capacities (limits on what the body can do and for how long, based on previous adaptations to training and experience) and Pacing (the skill of metering your bodies energy and abilities appropriately to the length of time of the endeavor).  I’ll discuss all of these aspects in future blog articles in this series.


Strength is about overcoming resistance.  You can’t hold your skeleton up without it!  We develop our baseline of functional strength through resisting gravity every day of our lives.  We can also develop strength through activities that use our own body weight as resistance (such as push-ups and pull-ups) or through lifting weights.

The discussion of strength expands into patterns, such as pushing, pulling, squatting, bending, and hip separation.  We can talk about all the different implements that are available for resistance training: barbells, dumbbells, kettlebells, sandbags, stones, and so much more.  Volume (reps & sets), intensity (loads), complexity (number of joints involved), tempos, and contraction styles all play their role.  The point of strength training is to change the physical structure of your muscles and other tissues, the nervous system that sends instructions to them, and the mitochondria that supply them energy to do that work.

Movement Ability

My third category of physical fitness is the ability to move.  Some people think about this as “mobility” or “movement skill”, but I group those things together.  Mobility means that your body has to be free of restrictions that would stop it from getting into certain positions or moving in different planes.  Movement skill means you have the motor patterns and confidence to move in these myriad ways.

You’re developing movement ability every time you do anything physical.  You did it for years as a kid when you were playing outside, chasing friends and climbing trees.  Throwing and catching is great for this, so is dancing.  There are (possibly) infinitely-varied ways for human beings to move.  Disciplines such as Yoga and Gymnastics help illuminate some of that variety.  If your tissues don’t let you move in the ways you want to, it may be due to physical restrictions (that might require water, rest, and blood flow to improve), or it may be due to weakness (which will be improved through conscious, strengthening movement).

That’s what I’ve got for today.  Check back with me on Monday when I will explore the idea of Spiritual Fitness.

Published by nicnakis

Nicholas |nik-uh-luhs| n. a male given name: from Greek words meaning "victory of the people" John |jon| n. a male given name: from Hebrew Yohanan, derivative of Yehohanan "God has been gracious" Nakis |nah-kis| n. a Greek family name derived from the patronymic ending -akis (from Crete) Amha |am-hah| n. an Ethiopian given name meaning "gift", from Geez Selassie |suh-la-see| n. Ethiopian name meaning "trinity", from Geez

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