Flexibility vs Mobility

This post is all about breaking down the movement of your muscles and joints as separate entities. You’ve probably heard these words thrown around interchangeably, for the sake of clarity (and our sanity) I’m going to give some general definitions to help you understand these better and be able to differentiate between the two. Both flexibility and mobility fall under the bigger term range of motion, with flexibility describing the range of motion your muscles have and mobility describing the range of motion your joints have. Now obviously one cannot function without the other, in order for your muscle to get into its maximal range of motion (stretch) the joint it is attached to must be moving fully, and in order for a joint to be able to move through its full range the muscles must be able to move fully with it. There are many different types of joints throughout the body with varying degrees of mobility. Your shoulder, for example, is a ball and socket joint allowing much greater range of motion than your knee, which is a hinge joint and designed to move with less motion.Mobility is a more specific measure for each particular point which we have normal ranges for, so while your trainer may be telling you to stretch more to reach that maximal range, the problem may actually be with your joint mobility. But how do I know if it’s my muscle or my joint that isn’t moving, you may ask!? Sometimes it can be tricky to distinguish, but sometimes it’s not. For example, if you fully flexed (bent) your knee but were only able to get to 110 degrees of flexion, vs the normal 140 degrees of maximal knee flexion, because you felt an intense stretch and pain in the quad muscle, it is more than likely a flexibility problem. If you were unable to bend the knee more than 110 degrees and didn’t feel any pull in the surrounding muscles but more like that joint was stuck at that point, that’s more likely a mobility problem. Once you distinguish what you need to work on, you can then focus on fixing the cause of the problem.

Another entirely separate issue that can occur is hypermobility, or hyperlaxity, which is when the ligaments surrounding a joint become slack and are no longer stabilizing that joint, allowing it to move through excess ranges of motion beyond what it was ever designed to do. Being hypermobile does not mean that your muscles are flexible. In this case your ligaments over stretch to make up for the lack of stretch in the muscle. Ligaments are not made up of the same tissue as muscles and they do not have elasticity like a muscle. Think of your muscles like a brand new rubber band with lots of spring, and your ligaments as silly putty, once you stretch the putty out it loses all tone and starts to sag down the middle doesn’t it.

Now your hip can “stretch” up to your nose while still having extremely tight hamstrings. Things like yoga were you are folding forward 20 times in an hour were your pelvis doesn’t move an inch and the ligaments (aka support) of your lumbar spine are being slowly stretched out like that silly putty makes me cringe, and it gives a bad name to yoga because you’re not doing it correctly. This looks natural right?!

The difference in a joints correct maximal range of motion would feel like an actual muscle stretch while still supporting the joints, can you feel the pull???

This blog was inspired by Nutritious Movement blog by Katy Bowman.