The Muddled Meaning of Mobility

“Mobility” has become a huge buzzword in the area of fitness and health. The term gets thrown around quite often in online articles, but rarely is its true meaning explained. What exactly is mobility, why is it made out to be such a big deal, and why is it so good for me?

The general definition of mobility is “capable of moving, or being moved freely and easily.” The word mobilityas it relates to the human body refers to a joint’s ability to actively achieve a certain position – that is, to move the joint using the body’s own muscular strength and control, without any external assistance. This is the joint’s “usable” range of motion, the range of motion that you are able to access at any given moment, during any day-to-day activities.

This is in contrast to flexibility, a term that is often used interchangeably with mobility, despite not meaning the same thing. They sound similar, but they are not synonyms! Flexibility means “capable of being bent, usually without breaking.” When talking about the body, it refers to a joint’s ability to passively achieve a position – that is, to use no muscular effort or activation to get there. To get an idea of passive movement, picture a yogi grabbing her foot and pulling it up behind her head. While her joints can obviously get into those positions, it requires the external help of her hands to do so. It is very unlikely that she could lift her leg into that position completely on its own, without her hands pushing it into place. In this example, she has great flexibility but limited mobility. The crucial difference between the two is the way in which her body’s joints achieve the position. Any joint position that requires external help to get into is not a usable position, but is “un-usable” range of motion.

Despite the “un-usable” label, passive flexibility is not bad. It is actually needed in order to have mobility, but it is only one part of the equation. Mobility is a combination of flexibility, strength, and control. To have mobility, you need:

Lots of available passive range of motion (flexibility)  +  lots of strength throughout that range  +  great control over that range

From this, we can see that we have the potential to convert passive flexibility into active mobility through training. Using our yogi as an example, we could train her joints to have the strength and control to lift her leg behind her head unassisted, thus giving her the active mobility to match up with her great flexibility. All of her passive range would become “useable”, which is a very good thing!

Now that we have a better understanding of what mobility actually means, we can dive into why it is so important to have it, as opposed to just having flexibility. Mobility is the key physical ability of the body. If we know that having good mobility means having active control of joints, being able to move them into a ton of different positions, and having strength in all of these various positions, then it’s easy to make the case that having mobility in your joints is the single most important prerequisite to any activity that you do in sport or life. Without the ability to move your joints into the positions needed to do a squat, to take a shot in soccer, to reach overhead and paint the walls in your house, or to bend down and pick up your toddler, your ability to perform those activities safely and effectively is severely compromised. No matter how strong you are, no matter how fit you are…if your joints cannot physically get into the positions that you repeatedly ask them to, your performance and your body will suffer.

Mobility is the base of the training pyramid, and it undergirds absolutely every other physical quality that you can train for (aerobic capacity, strength, power, speed). Mobility is what allows you to pursue and train for all of those other qualities without getting injured, without wearing joints down, without spending undue amounts of time and money on trips to the doctor or the physiotherapist. Mobility is what keeps your joints healthy as you age and prevents you from losing the ability to do the activities you were once able to do.



Maintaining the necessary mobility to do all of your favorite activities into your later years doesn’t just happen on its own, though. Joints don’t maintain themselves – it takes time, intention, effort, and a lot of movement on our part. Consistently challenging and constantly using the active ranges of motion that you currently have in your joints is the key to keeping those ranges over months and years and decades. Think of a person you know who is older than you. Have you ever heard him or her say something like “these knees/hips/shoulders just don’t move the way they used to” or “I used to be able to [insert activity here] but my [insert joint here] just can’t do it anymore”? Most people would chalk this up to simply getting older, but in many cases the main cause is actually disuse rather than age. Losing mobility in your joints is only a consequence of natural aging if you let it be. The best way to prevent this from happening is to never stop using your joints through the biggest possible range of motion you can.

Is training for mobility fun? Not usually. Is training for mobility easy? No, it is in many cases much more difficult than strength or endurance training. Is training for mobility important and rewarding? Absolutely. It should not be overlooked, or skipped, or disregarded as less worthy than lifting weights or going for a run. Mobility training is an investment in your body, a very long-term one. If you prepare your body to its very best ability to handle the tasks that you throw at it, you put yourself in the best possible position to not only crush life’s daily physical demands, but to keep your body as pain-free and injury-free as possible while doing so.


Erica Saunders, BPE, CSCS, FRCms