Flexibility vs. Mobility…What’s the Difference?
By: Keri Sotak, MS, ATC, CES, Owner of The Athletic Training Room, Oakland
Key Words: Flexibility, Neuromuscular Control, Mobility, Functional Mobility
“Grab a foam roller. We are going to work on mobility before our workout today.”
“The more flexible your hamstrings and hip flexors are, the more mobile your hip will become.”
I am guilty of saying the above statements at some point in my athletic training career. Until several years ago, I did not fully understand or appreciate the difference between flexibility and mobility. It’s the same thing, right? Boy, was I wrong! Once I understood the difference between the two, it drastically changed the way I look at the body, movement patterns, and my overall patient outcomes. This article will break it down to help athletic trainers, fitness professionals, and individuals seeking to better understand their bodies be able to identify the differences between flexibility and mobility exercises that are incorporated in their rehabilitation routines.
Flexibility can be defined as having the ability to bend without breaking. Flexible materials, such as connective tissue, can be modified and adapted when a force is placed upon it, either passively or actively. Passive and static stretching are examples of forces we place on muscles to obtain increased flexibility. Passive stretching is when a force or individual stretches the muscle for you, whereas static stretching is when the muscle is stretched by the individual themselves. There is an enormous amount of research focusing on types of stretching and parameters to obtain short and long term flexibility gains. Much of the research concludes that passive and static stretching result in short-term gains, while static stretching routines over several weeks result in long-term flexibility gains. More recent research has also concluded that foam rolling produces increased muscle flexibility. Overall, it is clear that stretching and foam rolling lead to increased muscle flexibility. So, does this mean the joint will move more freely whenever we want it to? Not necessarily.
The key difference between flexibility and mobility is neuromuscular control. We can stretch our hamstrings all day, however, this does not mean our body will be able to obtain that new range of motion when we need it in a functional movement, such as a squat, getting in and out of a car, or swinging a tennis racquet. How many times have you stretched your shoulders to obtain more overhead shoulder flexion to help with your overhead push press or snatch, but when you perform the movement, you find yourself bending your spine back to obtain the necessary range of motion instead? This is because shoulder stretching alone does not train the joint to use that range when it is needed. Neuromuscular control is the process in which our nervous system works with our muscular system to unconsciously obtain joint positions when performing active and functional movements. When we use passive or static stretching, our neuromuscular system is not talking to our nervous system and telling it to remember that position for the future. When we stretch a rubber band for an hour, we cannot expect it to actively hold that position when we take away the external force that is stretching it. Muscles act in the same way as that rubber band.
Our body will naturally protect itself if a joint starts to move into a range that it is unable to control. Therefore, we must train our joints to be controlled and usable within the ranges it possesses, which is mobility. Mobility can be defined as the ability to move or be moved freely and easily. Functional mobility is the ability to actively achieve a range of motion. Mobility requires both flexibility and neuromuscular control – once we have a greater range of motion (flexibility), we must teach our joint how to use and maintain that new range (neuromuscular control).
If stretching leads to increased flexibility, what leads to increased mobility? Mobility exercises should include two key components; the new range of motion (flexibility) and strength training. If our nervous system needs to talk to our muscular system to obtain mobility, strength training is an easy way to get the two systems to talk to each other. We must obviously work within safe parameters when strengthening a joint in a newly obtained range of motion, which makes isometric contractions a key component to mobility exercises. An isometric contraction is when the muscle is activated, but not shortened. An example of this is holding the end of a kitchen counter and trying to perform a biceps curl. The biceps muscles are contracting, but the muscle is not shortening because the elbow is not flexing. Once the individual has obtained an increased range of motion, the joint should then use that newly acquired range by way of an isometric contraction to teach the body that it has a new usable range. Mobility exercises can also progress past isometric contractions and into isotonic contractions once the patient has shown they can actively maintain the new range. An isotonic contraction is when the muscle is being activated and shortening, such as holding a dumbbell in your hand and performing a biceps curl. If I have a patient whose new range of hip flexion is 90 degrees and they are able to perform a supine (on their back) straight leg raise to 90 degrees without weight, I may then have them perform hip flexion and extension exercises with a resistance band through the full range (0-90 degrees). Having this new usable range of hip flexion will help the joint move freely into that range when the patient performs a squat during their exercise routine. If the patient were unable to perform hip flexion to 90 degrees and they tried to perform a squat, the individual would likely have pain or find another way to get into the position, leading to poor form and increased risk of injury. Mobility can oftentimes be overlooked by active individuals, however it is a very important component to body movement.
In summary, flexibility and mobility are not the same. Flexibility does not include neuromuscular control, therefore flexibility alone does not allow joints to be actively used within the increased ranges of motion. However, mobility includes flexibility and strength training to incorporate neuromuscular control in order to obtain usable ranges of motion. Mobility exercises should be performed by any individual with goals ranging from general joint health to injury prevention, rehabilitation, and pain reduction.