Kelly Starrett of The Ready State just release a video clip explaining how he defines mobility and stability. Kelly is, for those who don’t know, a Physiotherapist, author and one could say the father of Crossfit mobility after he started his mobility coaching under the name of MobilityWOD or MWOD (now renamed as The Ready State). Here’s the video. It’s pretty short, so have a look.
In short, he’s saying that stability is part of any movement that requires stabilisation and that mobility is Range of Movement (ROM) + technique and goes on defining technique being the movement or motor control. Whereas I agree with Kelly on principal, I tend to use a bit different definition and bring on another term.
Flexibility = passive range of movement; how much someone else can move one’s joint from one end range to another.
Stability = controlled movement range. This I also divide into two: active stability & passive stability. Active stability is muscle controlled stability. If one stands on one foot, muscles are working hard to keep the body stable. Passive stability is created by connective tissue supporting the body to keep the stability.
Mobility = Flexibility + Active Stability: Appropriate range of movement, controlled by the muscles.
Why is this important? I find that in my practice, the best example of this is ankle mobility. Many people lack the appropriate range of movement on ankle joint, making it difficult, painful or even impossible to sit in a squat. Now a squat requires mobility on other areas as well, but we’ll focus on ankle as an example. There are many causes for the lack of appropriate ROM, mostly due to people not spending time in a squat position anymore. Adding to that is shoes with high(ish) heels, thick & soft midsoles and hard soles preventing the foot & ankle to function in a natural way. Calf muscles, gastrocnemius, soleus, tibialis’ and number of smaller muscles become weaker when not being used in full ROM. This lower leg muscles group is one of the most important mechanisms for movement as they stabilise the body, they keep the body upright. When this group gets weak, someone or something else needs to step in and that’s connective tissue, or fascia. Myofascial (muscle & fascia) cells react to demand. If you lift weights, the muscles get stronger, and if your muscles can’t get stronger fast enough, then the connective tissue, fascia will get stiffer and thicker to create that support.
When the calf muscles are weak, and can’t actively support the stability of the body, the connective tissue takes over, gets thicker & stiffer to create stability. This is how the body protects itself from injuries, which is great, but if the goal is to keep a full ROM, then this makes movement difficult. When the ankle gets stiff and is not moving enough and the movement of the body still needs to happen somewhere, other joints need to move more or differently, in this case knees and hips. Many of my clients have issues with their movement, often due to stiff ankles. This affects different people, some high level athletes like Rugby players, who need the stability for their sport, others overweight people, who need the stability to keep the top heavy body moving with control.
Key to injury free (ankle) movement is appropriate range of movement over joint (connective tissue) with enough control (muscles) to stabilise the body. This means flexibility and strength. Increased movement and flexibility can be gained by myofascial work and mobility exercises like this:
Once the increased ROM has been achieved, muscles need to strengthened to keep that active stability. Such exercises are deep squats, cossack squats, multi-directional lunges (forward, backward, lateral, angle) and banded ankle movement (dorsiflexion, plantar flexion, inversion, eversion).
If you have any questions or suffer from stiff ankles, get in touch.