What’s the Difference Between Mobility and Flexibility?

by Will Safford
Performance360 Coach, CSCS, CPT, USAW, StrongFirst SFG

Mobility and flexibility are terms that get thrown around in unison all too often. Aren’t they the same thing? Is there even a difference? If I stretch more won’t I become more mobile? These are innocent questions that pop up regularly, however, there are fundamental differences between flexibility and mobility. Advocates of each modality will tout the benefits of one over the other, but both are important, and time and attention should be given to each.

There are advantages to gaining both mobility and flexibility, and key factors like when to perform one over the other are important. We’ll break down both and give you a better understanding of why and when to do each.


Flexibility is the modality most of us know, and relates to stretching and the muscles. There are many types of stretching including dynamic stretching, PNF stretching, etc., but for the means of this article we’ll refer to static stretching, or holding a stretch for time, as this is what most people think of when they think “stretching” and “flexibility.”

Remember doing the sit-and-reach in grade school? You had to desperately reach as far as you could down that silly box or measuring tape. For some of us this was a dreaded day in gym class, for others (cough…ladies) it was easy street. This is static stretching. Static stretches like touching your toes or holding a chest stretch for time will improve your flexibility, i.e. the elasticity and length of your muscles. Muscles, not joints, become flexible by stretching and lengthening them.

Yoga For Athletes Pacific Beach

Yoga is an excellent practice that typically improves flexibility (although it may improve some aspects of mobility) by holding poses (stretches) for periods of time. For those of us who are chronically tight, this is exactly what the doctor ordered and a main reason why Coach Julianne’s classes are so beneficial.

Although yoga may be quite the workout for some of us, there is typically no strength component involved with plain, regular static stretching – one of the key differences between flexibility and mobility. You simply attempt to elongate the muscles over time.


Long, flexible muscles are important for reaching full ranges of motion, optimal muscle performance, and preventing imbalances between muscle groups, which could lead to injury. Residual tension in the muscles can lead to stiffness and pain, muscle strains and tears, and an inability to fully express movement. Tight muscles also prevent the efficient flow of blood throughout the body, making it less able to bring nutrients into, and waste products out of the cells.

There’s a saying in the industry, “a tight muscle is a weak muscle.” Muscle contractions occur when muscle filaments inside muscle fibers slide along one another. If your muscles are tight and are in a shortened position, these filaments cannot slide optimally, decreasing the output of your muscles.

Many times, tight muscles are also “overactive.” Overactive muscles disrupt the balance between surrounding and opposing muscle groups, which will have a negative effect on posture and alignment. When a muscle is overactive there is usually an opposing muscle that is “underactive”. For example, when your chest muscles are chronically tight, chances are your rhomboids and lower trap muscles are weak, resulting in a rounded position of the shoulders.

These types of imbalances wreak havoc on your posture and position, and are a perfect recipe for injury. They should be addressed and resolved, not just to prevent injury, but to ensure optimal performance during your time in the gym.

The issue with stretching is that over time it can also stretch your tendons and ligaments along with your muscles. Tendons and ligaments are not meant to be loose or overly flexible. They are essentially a combination of muscle and bone, and connect muscles to bones and bones to bones. They provide stability to joints, and are meant to have some tension and rigidity within them to do so. When tendons and ligaments become overstretched your joints become less stable and more susceptible to injury.

Like anything, just don’t overdo it.

This is where mobility comes in, and is why stretching should not be your only means of loosening the body.


Mobility is the ability to express full range of motion (ROM) of your joints. Where flexibility relates to the muscles, mobility relates to the joints. To illustrate mobility, raise your arm straight up in front of you so that it’s directly overhead like you’re answering a question in class.

Now, can you get your biceps muscle directly next to your ear? Or does is stop a little short of fully vertical? Now do the same movement but out to the side. Can you still get your biceps next to your ear? If not, you’re lacking mobility and don’t have full range of motion of your shoulder joint. Boo hoo.

What happens when you lack full range of motion? Typically, the body will compensate with a dysfunctional movement pattern to complete a movement. For example, let’s say you lack range of motion in your ankles. To compensate for this when you squat, your torso will fall forward or your feet will turn out or something else up the chain will falter. Or in the case of the limited shoulder ROM, you will arch backward to complete the overhead press. Sometimes you can get away with these dysfunctional patterns, but over time and when under load, injury is lurking just around the corner.

Mobility Class

Beyond joint range of motion, mobility includes a strength component which flexibility does not. Not only do we want full range of motion in our joints, we want to be strong in these extended ranges. We want to have full control of the joint when its at its endpoint and be able to stabilize and maintain optimal position when working through a movement. Effective mobility drills will gradually push a joint beyond its current range of motion, gently stretch tendons and ligaments, making them stronger and more resilient in the process, and actively stretch tight muscles as well.

Also, your joints don’t have a blood supply like the muscles do. The job of your blood is to transport nutrients into cells and carry waste products away. Joints are nourished instead by what’s called synovial fluid. Mobility drills bathe the joints in this ever-important synovial fluid, which lubricates and sustains them, making them healthy and resilient.


So why is mobility important? Having full range of motion of your joints means you can fully express movement. You’re not short changing yourself in your workouts by completing ‘partial’ reps due to mobility restrictions. You get more from your workout, you work your muscles more completely, and ultimately, you can perform to your full potential. Additionally, you greatly reduce your potential for injury when you have complete range of motion, strong connective tissue (tendons/ligaments), and well lubricated joints. When people get injured it’s typically at the joint, not the muscle – a shoulder injury, knee pain, etc. Mobility drills address the joints before injury ensues.

There aren’t many cons to mobility training except that it’s time consuming and requires consistent dedicated effort. Your range of motion at a particular joint can literally change every day based on a number of lifestyle factors, like how and how long you sit and stand, how you breath, your emotions, your genetics, your posture, your previous workout, etc. That’s why mobility training is a never ending practice that takes commitment. Furthermore, as we age our mobility declines, and even more concentrated effort is needed. Sorry, life’s not fair.


Now we understand the what and the why behind mobility and flexibility, but what about the when?

Flexibility or stretching sessions are best reserved for after training or completed as their own session, like a yoga class. You never want to stretch statically before a workout, as it actually decreases your strength and promotes injury. Save the stretching for after your workout when your muscles are warm and elastic. Spend a minimum of 30 seconds on each stretch – ideally two minutes per stretch – and allow the muscles to lengthen over time, don’t force it. Most folks badly need to stretch more and improve basic flexibility.

Mobility drills should be done before your workout as a warmup or as their own session. Mobility drills, as mentioned, are dynamic and move the joint beyond its current range ofmotion. Typically, these drills are done for repetitions, however, some can be completed for time as well, with two minutes being the ideal hold time. Again, don’t force your joints aggressively beyond their ROM, gradually increase it over time.

Always mobilize joints you will be using in your workout before hand. For example, the day’s workout calls for 5×5 Front Squats. Be sure to mobilize your hips, knees, ankles, and wrists before you start squatting. Stretch the muscles you worked afterward. In this case, stretch your quads and glutes. If you’re riddled with injuries, you’re one of the lucky ones who gets to spend even more time mobilizing and stretching. And if you’re one of the rare few who never gets hurt, first praise the many-faced god, then get yourself to one of Julianne’s mobility class, because time catches up with everyone.

Today was my perspective on the matter both as a coach and a competitive athlete.

We can all benefit from more mobility and flexibility, regardless of current ability, so commit to it and stay loose.

Will Safford is a coach at Performance360. He is certified through the CSCS, USA Weightlifting, StrongFirst Kettlebell and is a Purple Belt in Jiu Jitsu.