Mobility vs Flexibility: What’s the Difference?

This is a hot topic in the world of sports injury and health and fitness: mobility vs flexibility. You have probably seen hundreds of Instagram videos proclaiming you must improve your ankle mobility, or that your hamstring flexibility is holding your training back. But what do they actually mean, and what is the difference? We are here to clear that up.

The textbook definitions run something like this. Flexibility: the range of motion in a joint or group of joints, or the ability to move joints effectively through a complete range of motion. Mobility: the ability to move in one’s environment with ease and without restriction. Two pretty vague definitions which do not clear much up - so at NRG we use slightly sharper versions of both, and we believe the two are equally important for human health and performance.

Flexibility, as we define it, is the complete range of motion of a muscle (or the whole body) with regard to stiffness and inhibited movement. Range of motion is how far the body or a muscle should naturally be able to move. A flexible person has a complete range of motion; someone with poor flexibility does not.

Take an example everyone has been asked to do at some stage: touch your toes. Some people feel stiffness in the hamstrings and notice their hands are nowhere near their toes. The stiff hamstrings are inhibiting the body from moving through its proper range - they might shake, sweat, or even feel pain in the area from being so inflexible.

Mobility, as we define it, is the ability of the body’s articulating bone surfaces, connective tissues and muscles to work in unison to move the body through a normal human movement pattern. In plain terms: the way the bones move over each other, the ligaments that connect bone to bone, the tendons that attach muscle to bone, and the stiffness of the muscles themselves - all working together.

For example, if you drop into a deep squat and it feels stiff at the front of your ankle, your chest leans forward and the position feels uncomfortable, that suggests the ankle has poor mobility. The bones of the ankle are not moving well over each other, which affects the connective tissues around them, which in turn causes the muscles to stiffen.

The simplest way to remember it: flexibility relates to muscles; mobility relates to joints.

The two directly affect each other, though. Tight pec muscles will limit the mobility of the shoulder joint, preventing normal motion. Poor ankle mechanics will limit ankle mobility, which then has a knock-on effect on calf flexibility and stiffness.

So next time you see someone talking about flexibility or mobility online, break it down: do they want you to mobilise a joint before applying normal motion, or increase the range of a particular muscle? Ask which would benefit you more - then give it a go.

Struggling with stiffness, mobility or flexibility? NRG Sports Therapy is a sports injury clinic in Bloomsbury, Central London. Book an injury assessment and we will build you a plan to get you moving pain-free.