Flexibility vs Mobility: The Importance of Differentiating

May 05, 2021

by, Dr. Kate Dowd, PT

            Today’s fitness world is filled with buzzwords surrounding the benefits of becoming the next gumby impersonator with regards to their body’s ability to achieve certain pretzel-like positions.  The terms “flexibility” and “mobility” are often used interchangeably.  Aren’t they the same thing?  Range of motion (ROM) is range motion after all.  Or is it?

            With the emergence of available programs all over the internet claiming to improve a person’s ability to move their body, we need to start recognizing the very important differences between types of ROM.  The truth is that not all ROM is created equal.  We can’t equate the ability to touch your foot to your head with having a strong and injury-free life inside and outside of the gym. Let’s start by creating a common language surrounding these popular terms so that coaches can provide more effective solutions to the ROM problems they see with their members on a daily basis.

            Flexibility can be defined simply as PASSIVE range of motion.  It is the amount of range of motion possible at any given joint when it is placed under some sort of external load like gravity or a helping hand.  Consider what it feels like when you take one hand and bend back a finger on the opposite hand.  Anatomical structures like the shapes of our bones, the tautness of our ligaments and joint capsules, the length of our muscles and tendons surrounding that finger will allow to you to push a certain amount before your brain recognizes signs to stop. This is how FLEXIBLE your finger is and no amount of verbal cueing is going to increase this range.  Why are coaches surprised then when their client get frustrated at cues to “get the knees more forward” in that overhead squat—maybe the fact the client only has 1” of ankle dorsiflexion available on one side went undetected because there was no proper screening in place.

            Mobility, on the other hand, is considered the ACTIVE range of motion at a joint.  It is how much of the available ROM we can actually access, use, or generate power through on our own accord.  How much motion do you have at that finger when you don’t give it any help from the opposite hand?  You’ll notice it doesn’t move nearly as much as it does with assist.  This is an example of how mobile your finger is.  The truth is you’ll never have more mobility than you do flexibility and guess what: that’s normal!  Together, flexibility and mobility make up what we know as movement.

            In the world of fitness, there are positions that must be achieved with the various movement patterns.  As important as it is to have a prerequisite amount of ROM available to us, it is imperative that we also have control over that prerequisite ROM.  Being able to move a heavy load through a full depth squat or catch a heavy clean & jerk should not be purely dependent on momentum or the elasticity of passive structures.  For the sake of the health of our joints and being able to train for a lifetime, we should be able to move the loads we are training with through the entirety of the movement we are asking someone to complete.  How many times have you watched someone bounce out of the hole on a heavy squat? They get credit for the rep in that moment, but at what cost over the long term?  What happens if they perform this technique repeatedly for high volume and load?  Over time, this can leave a person at significantly higher risk of injury because they are placing excess stress onto passive structures of a joint due to their lack of strength in the end range.  Often you’ll hear clients complain of “tight hips” during a squat so they spend 20 minutes stretching or foam rolling before and after squat day.  This same person can also lay on their back and bring their knees up past their rib cage without a care in the world.  The joint obviously has the ROM available to achieve the desired position (and then some) so what exactly ARE they “stretching”? This client doesn’t have a ROM “availability” issue, so don’t expect change to happen with foam rolling.  This person has an “accessibility” issue and the real fix is strengthening.  

            Assessing and recognizing the difference between a flexibility issue and mobility issue will mean coaches will (much more effectively) have their clients spend time at end range positions to elongate passive tissues or provide eccentric load to musculotendinous restrictions that are limiting a person’s flexibility.  It will provide them information that leads them to program bottom squat holds and high step ups to increase strength in the depth of the squat or overhead holds and carries to improve overhead mobility to catch that push jerk without soft elbows.  What ranges of motion are best for a client to be working in, given their current flexibility and mobility profile? Which tools can you use within the scope of a coach to give your clients the solutions to their ROM problems to improve overall performance? A simple movement screen can help you choose the correct and most effective tool for the task at hand and be the difference in keeping clients safe while they train for a lifetime. It’s time to be more strategic and stop wasting valuable time trying to stretch away strength problems and being frustrated as they try to (and fail at) cueing a client into a position their anatomy won’t allow. 


Coach smarter and #TurnPro.