Last week we had a question from a client that I think a lot of our readers also wonder about: “Dr. P, I know we’ve been working on the mobility of my muscles and joints, strengthening and lengthening to improve my performance and get me back to doing what I love. What I’m wondering is you usually use the term “mobilize” or “mobility” – isn’t this the same thing as flexibility?”
This is a great question and we know it can get confusing when flexibility and mobility get used interchangeably in day to day conversation. But it might surprise you that this is not true! They each refer to something very unique. Read on to learn the difference:
Flexibility: How Far Can you Bend?
Think of a rubber band. You’re holding it with both hands, two fingers gripping each side. Do you have that picture? Okay, now move your hands further apart, watching as the rubber band stretches. Pull farther, and the rubber band stretches more. But finally, you get to a point where the rubber band doesn’t want to stretch anymore – and if you do stretch it, it snaps.
This illustrates the definition of flexibility. In the context of muscles, flexibility is the ability of a muscle to lengthen passively through a range of motion. Here, the word “passively” means that there’s an external force causing the muscle to stretch, like the force of gravity pulling on your upper body as you bend to touch your toes. In other words, it’s how far apart your body can stretch when it’s pushed or pulled by something else.
If that still doesn’t make sense, take a look at your hands. Hold out your index finger on your dominant hand like you’re pointing at something. Try to raise your index finger as high as you can without pulling it. That’s your index finger’s active range of motion. Now take your other hand, grip the index finger on your dominant hand, and pull it straight back as far as it can go without pain. That’s your finger’s passive range of motion – and the more flexible that joint is, the farther back your finger can go.
Mobility: How Well Can You Move?
This brings us to mobility. Mobility is different from flexibility in one simple and important way: flexibility is how far a part of your body can move with assistance from an external force, and mobility is how it can move on its own.
Let’s illustrate hip mobility as an example. Stand up for a minute and lift up one knee as high as it can go – but don’t pull it up with your hands. Now move your knee in a big circle, clockwise and then counter-clockwise – as big as you can make it without feeling pain or injuring yourself. This knee circle gives you a picture of your hip mobility; it shows how far your hip muscles can move your knee on their own.
You can test the mobility of any joint by seeing how far you can reach. Try your wrist if you want to start small, or go big and test out your shoulder. In each self-test, you’re looking to make a big circle with the joint to see how far you can actively move the joint.
Mobility builds on flexibility because it requires an unrestricted range of motion.
A joint’s active range of motion is never going to be greater than its passive range of motion. In fact, it’s always the other way around – a joint can only move actively inside the range of motion in which it can move passively. In this way, limited flexibility means limited mobility, and increasing flexibility is a pre-requisite for increasing mobility.
Mobility and flexibility may get used in place of each other in day to day conversation – but now you know the real truth! Mobility builds off of flexibility and shows your bodies real ability to move. Have you ever been told that you are hypermobile or “extremely flexible”? Your body has a different set of needs in order to stay healthy and active. Check out our Hypermobility section to learn about it!