Thursday, October 22, 2009

Mobility vs Flexibility - is there a difference?

Often it seems the terms Mobility and Flexibility are used interchangeably. While related, they're different, and the differences are worth considering. It's hard to find concrete references to definitions of the terms, though. The best ones i know is that flexibility is about what a movement around a joint is possible to be, whereas mobility is about the control of the range of motion one has in an action/movement around a joint. That may seem a nice distinction, but if we look at flexibility as what's physiologically possible, and look at mobility as what we can volitionally control, then we have a perhaps better model for understanding performance, and why mobility work may be more effective than stretching or rolling for a range of issues.

The splits: mobility vs flexibility
Many people will say that doing the splits is an example of being a very flexible person. Maybe there are some cases of some people being hyper flexible, but apparently the splits are natural; not exceptional.

We see babies having no problem with the splits and all varieties of movements. Likewise, kinesiologists, chiropractors and doctors will tell us that anyone can do the splits when we are unconscious. Now why would that be? They are reflecting the physiological flexibility that is possible in that joint given its current condition (pretty relaxed).

So what happens that we lose that "flexibility" when we wake up. In the context of the definitions we have here, we'd say that our mobility is restricted. How might we address this?

The Splits as an Example of Threat Modulation.
In that seeming waking loss of mobility, partially the muscles are now contracting that previously allowed the movement.

Most training programs for learning to do the splits are about stretching - and lots of it. But what does that mean? stretching is in part a temporary condition of changing the contraction properties of the muscle; limbs will "tighten up" again. But then when we talk with some folks who stretch a lot or practice yoga alot, they say how much their range of motion has improved from their practice. Has something therefore fundamentally changed in their muscles? Or has something changed in the nervous system signalling the muscles to relax on demand better? Or have they just gotten stronger (better muscle fiber control/nervous signalling?)

Some in the joint mobility community would suggest that the ability to do the splits is more about threat modulation than stretching: it is the nervous system learning that it's safe to move into these postures. After all, the golgi tendon's job is to say it's ok to allow a muscle to assume a position - that's a nervous system response that enables muscle and tendon responses; not something that is really part of the muscle.

So if we accept the idea that we are wired for survival and not performance, and we say that learning to do the splits is a good example of threat modulation, that means that not doing the splits is detecting threat. Why would the body see the splits as a threat for some of us?

Are we able to exert force quickly if we are stretched out? Can we flee? Or does that mean there's a certain potential limitation to us if we seem to over stretch? Can we currently exercise full range of motion from that edge-of-stretch position? if not why would the CNS let us go further? Does that mean *not* doing the splits is a sign that we don't have the strength to respond from this position and so we ain't going there?

Mobility Work Rather than Stretching.
The idea of mobility work around joints - like z-health - and range of motion work - again like z-health - is that we can, leveraging properties of the nervous system like mechanoreception, demonstrate well being to the CNS to enable new ranges of motion which means better mobility which means better performance.

Just this weekend at the z-health kettlebell workshop in London, i had the privilege to work with an athlete who said he had real trouble breaking parallel in his squat. He was sure he had a tight IT, hip flexors - everything. We worked for literally about 30 secs - no stretching; just threat modulation and his butt was on the ground, first time. Why? Threat modulation. His body now perceived no threat to getting his butt down. So far that's what lengthy stretch practive has been - i speculate - in training for the splits: helping the CNS feel safer about these deep movements - that there's no threat: so PNF type stretching is a way to get that acclimatization to happen.

Dynamic joint mobility accelerates this process of acclimatisation.
No stretching required. Hence mobility improvements can be achieved rapidly for seemingly little or no direct effort: toe pulls for instance "release" what are often called "tight" hip flexors as well or better than deep lunges. How can this be that an action on the ankle lets the hip work? Systems are connected: if there is a joint mobility issue at the ankle - and its ability to flex is compromised, what's the point of letting the hamstrings relax that might compromise stability there?

Likeiwise these kinds of approaches can assist the acceleration of necessary strength work associated with actually *holding* positions (progressive isometric moves) at greater and greater degrees of former compromise (see Pavel Tsatsouline's Relax into Stretch for excellent guidance on such progressions; combine with a z-health coach (list) to get there even faster.).

The site of an issue is not always the source of an issue
So also, doing general mobility work around joints helps the *whole* system to perform optimally. As with the hip flexors, and that looking at them to relax may be inappropriate where a first step may need to be at the ankles, a general joint mobility program like R-phase moves through each joint in the body. It also suggests moving at four different speeds through these joints and of course in all directions. Why?

Try an ankle circle quickly and casually, and then try to slow it down: do some parts of the movement feel dead or jerky? does it feel different in each direction? Less control at one speed or direction than another? Speeds show the degree of control one has over a joint, and how well the muscles are firing to work that movement. Improve that simple control of range of motion and speed, and whole galaxies of performance open up. Why? mobility is related to muscular control; control muscles better in a movement, the movement improves. If there is an impedement to the range of motion, too, that also means that muscles are not getting mechanoreceptor information and that part of the muscle may not fire. At all. So getting action around a joint is a Good Idea.

Take Aways:
  • Flexibility is often associated with stretching: stretch more to improve flexibility. But flexibility is, by these definitions, just the degree of movement around a joint that is possible in that joint.
  • Mobility, however, is about how we can move ourselves - what our actual range of motions are
  • By doing mobility work we are communicating with the nervous system to enable optimally efficient movement.
  • By doing mobility work we can see that better mobility in one joint can have consequences for movement around another joint (ankle tilts affecting hip/knee range of motion by acting on hip flexors)
  • The site of an issue is not necessarily the source of an issue: wailing away on a hip flexor when the limiting factor may be the ankle is sub-optimal. General mobility work lets us get each joint happy at varrying speeds and positions.
  • Mobility is about threat modulation: is it safe to move into that range? mobility work is a way to practice that safety for performance.
  • Doing the splits may be about strength as a limiting factor rather than flexibility. Get the strength, do the mobility, the MOBILITY - the control of the movement will come.

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Franz Snideman said...

I must say I have been very annoyed by many Z health practitioners over the years(not you) due to their dogmatic and over zealous attitude toward stretching/massage. But, having done some Z-health with Geoff Neupert and recently Sara Cheatham, I must say I am more and more impressed with Z. I actually took some Z course with Eric Cobb back in 2001 and 2002 but didn't really feel any better or see any noticeable results. Well, that has changed. I have now seen some results with Z and am becoming more and more interested in Z. I am questioning the way I train myself and my clients.

Great write up MC!!! So I assume you do not approve of massage work? Do you feel their is a place of soft tissue work?

dr. m.c. said...

Franz, that's awesome to hear that Z is doing some good things for you. You are such a cool guy, re-checking your training stuff. Not always easy; Not everyone does that to be sure :)

as for massage, there's nothing that feels nicer is there than an excellent massage? so i'd hate anyone to think i "disapprove"

It's about context though and what is it possible for it to do?

Massage or any manual therapy can have great immediate effect for an acute process and to move you out of it, and sometimes that's great. But when the treatment becomes chronic - like you always have to go for a massage to get a shot of temporary relief - that reminds me of the definition of insanity - expecting if you do the same thing over and over you'll get a different result.

Manual therapy in these more chronic cases it doesn't seem has the same value for effecting change as self-activation. It only triggers a fraction of the mechanoreceptors for instance, and so the body it not building new maps for new self-driven demand.

so it's not that i "don't approve" -it's that i don't expect it to do in a lasting way what most of us need done to develop better movement rather than deliver what can only be temporary relief/pleasure.

lovely to see you here, Franz


Franz Snideman said...

thanks the for reply! Makes perfect sense MC! Keep cranking out the thought provoking posts!



helium said...

Try an ankle circle quickly and casually, and then try to slow it down: do some parts of the movement feel dead or jerky?

OK did some superslow ankle circles. Had a jerky part, moved through this part a few times in superslow, tried the full circle again and now I can do perfect super slow ankle circles. So What can I expect now? I mean, being able to perform slow ankle circles isn't something you can impress anyone with. You write "Improve that simple control of range of motion and speed, and whole galaxies of performance open up." Anything particular I should check? Anything I'm expected to set new PRs in (beside slow ankle-circling)?

dr. m.c. said...

helium, way to go exploring ankle circles and fantastic on improving them.

You seem to explore a lot about the body, so what if i ask you: if you can control your body better now, control movement around your feet especially more cleanly now, if you had to make the argument, what do you think the benefits would be of this better control?

(related post: iphase - train for the sprain)


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