The 'nervous' neural system

Our nervous system is, in my humble opinion, not considered enough or placed on top of the list of priorities as it should be by a lot of sportsmen and women as well as by the physios, therapists, coaches and trainers who look after them.

This is a huge and potentially dangerous mistake as neglecting this vital system of the body could possibly lead to a much higher risk of injury and can also mean failure to fully recover after an injury has occurred, let me explain further.

All to often after an injury physios tend to focus on getting and keeping the muscles strong and powerful, and the joints and tendons supple and flexible, now don't get me wrong, these goals are vital, but its not much help if the neural system that controls EVERYTHING in the body isn't working well.

Our nervous system penetrates and infiltrates every system of our bodies, it connects everything to everything, simply put without our nervous system our body cannot function, its our command and control center as well as our body's line of communication, and as any soldier will tell you, you can have all the firepower in the world but without an effective, organised chain of command together with clear lines of commincation the war will soon be lost.

This is no different for the body.

Without a signal / instruction from your central nervous system (this is your brain and spinal cord) which is then carried down the peripheral nervous system (the nerve plexuses, trunks, branches and fibres) a muscle wont, cant, doesn't move.

Simply put without an input, there is no output.

Now have you ever been to see the physio and he gets out the hammer looking thingy and taps just below your knee and your leg jerks straight out? Wondered why they do it?

Well we are testing your reflexes, these are involuntary muscle contractions (output) to a stimulus applied (input). This gives us a way to assess your nervous system, too much or too little output (muscle jerk) to the input (hammer tap) lets us know if there is a glitch in your nervous reflex system, and if there is a glitch it will affect the way you move, Why? Well walking, running and most movements are reflex actions, yes you do have some conscious control like if you want to go faster, slower, skip on every third step etc, but the majority of muscle action and movement is controlled via spinal reflexes through whats called your 'Central Pattern Generator' (CPG)

Sounds like something off Star Trek doesn't it…

“Cap'n the central pattern generator is offline”

But what has this got to do injury risks and rehab?

Well lets say that you have trained only one way or only played one type of sport for a long time, say you train on the same equipment or do the same exercises day in day out, your CPG and higher neural centres will get very good at producing quick and co-ordinated signals to produce fast smooth and strong muscle contraction for these particular movements, so your muscles work in the right order at the right time at the right intensity.

However do something different say train on another surface or do another sport, your neural system will not be as good, not as quick in sending the signal to the right muscle at the right time so making the muscle respond that bit slower, that bit weaker, that bit more uncoordinated.

A good example of this is a runner only used to running on flat even surfaces such as roads, suddenly ask that runner to run off road and it wont be long until you see them stumble, wrench a knee or twist an ankle, yet a regular trail runner 'probably' wont (there are obviously other factors to consider, but his chances will be less).

Why? Yes you guessed it, its due to the exposure the CPG and neural system has had, or hasn't had, the sudden onslaught of input to our road runners ankles, knees, leg muscles, tendons etc, etc as he runs across the uneven terrain is all new and unexpected, this means that the output signal down to said structures are that little bit slower and uncoordinated compared to our trail runner, so that signal to the muscle to prevent the ankle from rolling over is sent either a little to late or arrives to slowly to the muscle or the muscle reacts to slowly to the signal to stop the ankle from rolling over for our road runner.

The same principle for the neural system is also true when you have suffered an injury.

Firstly there is always trauma to our neural system with every injury, as I said earlier the nervous system is in every tissue, everywhere, our neural system can be, crushed, stretched, pinched, irritated and inflamed just as much as muscles tendons and ligaments, However unfortunately nerves aren't as pliable or adaptable as other soft tissue in our body, they can glide and slide through and around our bodies quite well but there are places of whats called 'fixity' places where a nerve is held 'firmish', normally these are where nerves go past or around bony prominences, such as when a nerve branch emerges from the spine, or like in our ankle example, when the superficial peroneal nerve crosses the ankle joint, or the suprascapular nerve passes through the scapular notch in the shoulder blade.

Research shows that a nerve has only to be 'pulled' or stretched between these points of fixity a very small amount to cause pain and damage. Only around a 4% stretch to a nerve is enough for it to register pain and cause minor damage and if its pulled more than 15-20% it can cause irreparable damage.

A fully damaged nerve will very rarely be the same again, either only sending reduced signals to the muscle, ligament, tendon or skin it supplies or sometimes none at all. But luckly the nervous system is very adaptable via a term called neural plasticity, this means that the neural system can work on finding alternate strategies to by-pass the damaged area and or recruit other structures to help.

The second factor to consider for the neural system is the amount of time it takes to heal/recover or the time away from your normal movement patterns. During this time your CPG etc is not having its regular input so it loses its ability to work as quickly and smoothly as normal, just like anything, muscle, joint etc…

“if you don't use it you lose it”

Again lets use the twisted ankle of our road runner as an example, so first the injury to the ligaments, tendons and the nerves around the outside of the ankle causes pain and inflammation etc, this means our runner can't walk for a week and can't run for a period of say six weeks. During this time he is having treatment for his swelling, his stiffness and his muscle weakness, he even did some balance work on a wobble board and a bosu thingy, and he is now completly pain free and ready to run, great so off he goes running with a fully flexible and strong ankle…

But, he feels awkward unsteady and sluggish when he runs, its nothing to do with the injury anymore, that's all healed his muscles are strong, his ligament is repaired, even his nerve is working ok, this is now due to his neural system.

 

It hasn't been fully retrained or exposed to a regular input after its time off due to the ankle injury so its output is affected, and yes if our runner keeps on running he eventually will get his CPG firing quickly and his neural system working again, but this can take a while (months sometimes) and all the time he is at further risk of injury as he is moving awkwardly and hasn't the output speed or reactions to help him if he re twists his ankle again.

 

Now imagine he broke that ankle and it was in a cast for 6-8 weeks and he hasn't done any walking let alone running. Think how deconditioned not only his muscles etc will be but what about his neural system. I often hear patients and physios talking about 'learning to walk again' after these types of injuries and they are right sort of, it's more about getting the reflex system of the CPG and central neural systems firing again

So how do you 'train' your Central Pattern Generator and neural system?

Well simply put through repetition, lots of repetition, lots and lots of repetition with lots of variety, lots and lots of variety.

You have to break down a pattern of movement like running into is parts and then get yourself or your athlete/patient to repeat said movement time and time again, at a low threshold at different speeds, in different positions, on different levels and surfaces for your neural system to experience lots of input in lots of different senarios for it to improve its output via quicker speed, smoothness and efficient muscle contraction.

Let's again take our road runner with his twisted ankle, not only should he have been doing ankle stretches and strengthening exercise and some proprioception work on a wobble board thingy during those six weeks of rehab but also lots of movement pattern drills, this is not just single leg balance work as most perceive it to be, and it shouldn't just be spent on wobble boards and bosu trainers etc although this does help by exposing the body to a different input. It should include movement drills specific to the sport or activity you or your athlete does, as well as some that aren't! and it shouldn't be just for lower limb injuries but for all areas, shoulder, hand, neck and backs etc.

You will always see a good physio, therapist or trainer spending time, a lot of time, with their athlete/patient going through some rather strange looking drills that can look like something out of either Monty Pythons ministry of silly walks or a dodgy rendition of Saturday Night Fever, with them walking and or waving their arms around in some rather peculiar positions, and to an outsider (and even sometimes the participant) it can look and feel like a complete waste of time, especially as they feel not that physically challenging from a sense of muscle fatigue etc, in fact it normally just feels weird and embarrassing, but what we are actually doing here is rehabing your nervous system. So please bear with us.

So my take home message is that if you have had an injury or want to try and avoid one, please spare a little thought for your neural system, especially the reflex action of your central pattern generator. If you do just one particular pattern of movement or exercise or sport then please change it occasionally and mix it up, train on a different surface, do your exercises in a different order, or faster, or slower, do them barefoot or in different shoes, try new things and let your neural system get acclimatised and accustomed to different inputs so its outputs are improved.

If you have suffered an injury and are having rehab, please don't just do the stretching and strengthing exerices and neglect those silly, daft drills that your physio gave you, as normally these will just as important for you, not just for your physios amusment (although it can be sometimes) and remember your neural system should be considered just as important to your recovery and eventual return to sport as strength and flexibility.

Thanks again, and I hope you continue to enjoy your injury free sport

Adam

 

 

 

About these ads