If you ended up on this newsletter it’s probably because you have some sort of interest in mobility and movement. But maybe you’re unsure about these terms and feel a bit lost with all the information available and presented to us.
You may also know that mobility and flexibility are both important concepts when it comes to health and performance. Today, I want to spend a bit of time discussing the two concepts, emphasizing the difference, and, moreover, why and when you should prioritize one over the other.Subscribed
What is the function of a joint?
Because these concepts can sometimes be a bit abstract, I want to start from the basics and explain what we mean when we talk about flexibility.
The human body is composed of different parts that articulate together around joints. Each of these joints has specific functions. The shoulder, for instance, has six functions (flexion, extension, adduction, abduction, external rotation, and internal rotation). The knee, on the other hand, has only four functions (flexion, extension, internal rotation, and external rotation).
For each of these functions, we can define a maximum angle to which we can move. This is the range of motion, and it’s the most important concept when we talk about flexibility and mobility.
Flexibility
The second most important concept is the distinction between active and passive ranges of motion. You’ve most certainly noticed that you can sometimes pull yourself into certain positions, but you cannot reach those positions using only your strength.
This means you have a passive range of motion—you can reach certain positions with assistance (an anchor, gravity, or pulling into something). This is what we define as flexibility, or passive range of motion. It’s essentially how far you’re able to go in a given position with external help.Subscribed
Mobility
In certain cases, you’ll need to use your own muscles to move and not rely solely on an external factor to pull yourself into position. This is what we call the active range of motion.
It accounts for the strength and motor control you have in those positions.
Mobility = Flexibility + Strength + Motor Control
End Range of motion
As you might have already noticed, we don’t have the same strength throughout the whole range of motion.
We are much stronger in the middle ranges of motion, and as we go to more extreme ranges of motion, we become weaker (see graph below). At the end ranges, we have no force left and need to pull ourselves into the positions.
Which one should you prioritize?
If you’ve read this far, you now understand the difference between active and passive ranges of motion. You may also be thinking that you can’t have an active range of motion if you don’t have a passive range of motion first. You’re absolutely right!
Flexibility is a prerequisite for mobility.
The first step is to assess if you have enough passive range of motion for the activities you want to do. If not, then you should develop some flexibility first!
If you already have enough passive range of motion, the next question is: Can you apply and resist force in those ranges? That’s where mobility work begins. By strengthening those passive ranges, you start owning them and gain access to more ranges of motion where you are strong.Subscribed
Why is mobility so important?
I like to say that mobility is the basis of everything. It allows you to strengthen the ranges of motion where you’re weakest. This is super important because many injuries happen in these end ranges. These are ranges we aren’t used to exploring and where we’re weak.
By exploring, developing, and strengthening them, we give ourselves access to more workspace and reduce the risk of injury
Bonus : The passive to active ratio
One way to know if you should include some mobility work in your routine is through the passive-to-active ratio.
Once you’ve established that you have enough flexibility, you can assess how much of it is passive.
This ratio should be around 1:1. If it’s not, it means you have a range of motion where you lack control or strength—making it a range at risk if you find yourself in that position.Subscribed
Key take away
- Joints move within a specific range of motion, defined by their functions.
- Flexibility is your passive range of motion—the positions you can reach with assistance.
- Mobility is your active range of motion—how far you can move and control a joint using your own strength.
- Flexibility is the prerequisite for mobility, but mobility builds strength and resilience in end ranges, reducing injury risks.
By understanding and working on both, you’ll develop a body that’s not just capable of movement but also strong, stable, and injury-resistant.