core stability, pure stupidity?

okay, I admit its an inflammatory title but I feel its an issue that needs debating and it probably got your attention. Its become a term used increasingly in rehabilitation, remedial exercise and even sports training. But what is meant by it and does anyone know if it is really desirable and beneficial? I also worry that these exercises, originally devised for people with spinal injuries, are widely used by athletes with no pathology! 

I wrote the following article in 2001 which had quite an impact, even resulting in abusive correspondence from several quarters - needless to say they were not scientific in nature! 

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In 1989 the International Union of Physiological Sciences Conference debated the head-neck sensory motor systems as a factor in movement and balance. As a result, over one hundred papers were written on the subject in the following three years. In the editor’s preface to the publications Berthoz  wrote: -

The need for a thorough analysis of all aspects of head movement control is all the more important because head movements are a core element of orienting behaviour involving a number of interactive sensory and motor systems.

It is therefore difficult to explain and justify the current popularity of exercises used by many therapists to promote what is known as ‘core stability’. These exercises were devised in response to the perceived problem of poor support. The patient is encouraged to concentrate on using specific muscles to stabilise the core to support an area known to have a weakness. The problem with this action is that it is contrary to the function of the nervous system.

Gerald Gottlieb, a respected scientist working in the field of motor control stresses that one of the functions of our central nervous system is to minimize muscle stress. This, he argued, is why we should not override this directive by concentrating on individual muscle activation during activity. Are we in danger of over doing it when we try to control the actions of specific muscles? Remember this is physiologically impossible anyway! Whilst the nervous system is in favour of minimising stress to help maintain free joint movement and reduce pressure on the internal organs, we are consciously doing the opposite. Following on the back of this paper sports scientist Dr Mel Siff writes: -  

… how can one prescribe specific set ways of recruiting muscles in any complex natural movement if research now shows that these highly deterministic patterns of muscle action are not characteristic of human movement?  

and

       Research into motor control has never shown that training of individual muscle actions   
       enhances skilled complex motor activities. The maxim of "the body knows of movements,
       not muscles" is constantly reiterated to emphasise this fundamental point. The learning of 
       the motor skills required to execute a given sporting movement are acquired by regular 
       practice of the movement itself, not by teaching isolated joint or muscle actions that are 
      believed to play some contributory role in the sporting movement.

We should not attempt to directly control muscle recruitment for movement or exercise, it should be the thought of an act that initiates our total muscle response and the subsequent movement that determines ongoing involvement. When the managing director decides to sweep the factory floor instead of staying in the boardroom making the big decisions, he interferes with the operation of the whole organisation.

If our innate balance mechanisms are allowed to perform their function unimpeded there is no need to consciously engage muscle or strengthen the middle of the structure independently. In the absence of interference, the reflexes responding to gravity will help to ensure optimum balance and movement.  

Mulder and Hulstyn’s research published over twenty years ago ('Sensory feedback therapy and theoretical knowledge of motor control and learning'. Am J Phys Med 63:226-244, 1984.) stated

       "Normal movement does not consist of isolated actions that are cortically controlled. Rather 
        it is a sequence of synergic movement patterns that are functionally related. Besides
        initiating muscle activation, which produces the movement, synergies also serve to maintain 
        equilibrium. Therefore, another goal of treatment may be to improve dynamic postural and
       movement synergies available, decreasing the tendency for excessive and prolonged 
       recruitment of muscle activity to stabilise posture during movement. Thus, muscle 
       re-education sequences should NOT be performed in isolated movements. Instead they
       should be incorporated immediately into functional, goal-oriented tasks".

More recently Stuart McGill Ph.D (Physiology) published a paper stating 

      "The task of daily living is not compromised by insufficient strength but rather insufficient
       endurance. After an injury it has been demonstrated that the motor system loses its fitness,
       and abnormal relationships of muscle activity occur. Endurance training is emerging to be
       far more important in stabilizing the spine than strength. Strong abdominal muscles do not 
       provide the preventive or therapeutic benefit that was thought. Sit ups, with knees bent or even
       abdominal crunches have not demonstrated any real benefit for the low back. Further, pelvic 
       tilts may actually make the low back worse. There is little support for low back flexibility to 
       improve back health and reduce the risk of future back trouble. Research is demonstrating that
       endurance has a much greater preventive value than strength. In fact, emphasis on endurance
       should precede specific strengthening exercise in a gradual exercise program. Increasing 
       evidence supports endurance exercise in both reducing the incidence of low back injury and 
       as treatment. This would include such daily activities as walking, cycling, swimming or 
       repetitive low demand exercise to specific muscles. Co-operative muscle activity is a 
       necessary prerequisite to obtain the desired endurance. That co-operative muscle activity
       is dependent on proper joint mechanical motion as is proper joint motion dependent on
       co-operative muscle activity." 

also

          …spinal stability is achieved with very low levels of abdominal co-contraction,  
          focusing on a single muscle is misguided, and that "sucking in" the TVA in fact 
          compromises, not improves, spinal stability.                ( my bold text )

So perhaps a misunderstanding of the problem has led to a short-term remedy. A number of therapists are starting to question the thinking behind core stabilisation techniques as to date there is no convincing clinical evidence to prove their effectiveness. Because it may appear to achieve a result and ‘feel’ good it is not surprising to find the core stabilisation theory featuring in numerous popular exercise philosophies. Again Dr Siff writes: -  

At the very outset, we have to dispel the belief that it is possible to focus on 'core stability' on its own. Unless one's entire body is off the ground or is immersed in water, the idea of stabilising the core separate from other parts of the body is sheer nonsense, since the ability of the core in all sports in which one is in touch with a static or moving surface depends strongly on peripheral stability (the limbs). If one is carrying out some movement such as lifting weights, doing aerobics, running, jumping or playing some ground-based sport, the body stabilises as a whole, with interacting contributions from the periphery and the core….. The world of core stabilisation currently remains far too heavily based in marketing and belief than in valid science.   

The actions encouraged to promote core stability may feel like they are strengthening the centre of our body. In the absence of ‘valid science’, they appear to protect the spine because it must make sense to support the body from the centre. But the theory ignores the role that limbs play in maintaining stability and the overall controlling influence of the balance and righting reflexes. The few disciplines that do recognise the importance of the head, neck and back relationship resort to what they know best to ‘improve’ it - exercising the muscles of the neck! The exercises designed to achieve this have the effect of increasing interference in an area that requires none. Alexander’s method to promote correct use of the primary control (the relationship between the head, neck and back) is not about right position or strength of the neck and shoulder muscles. In reality the only thing we can directly do in relation to the righting reflexes is to unknowingly interfere with their function. Anthropologist, Raymond Dart, wrote:

The prime factor about human body movement is that it entails the co-operation or integration of both conscious and unconscious mechanisms, i.e. the ‘will’ and the ‘reflex’.

To achieve the level of integration necessary for optimum movement we need to prevent the conditions likely to impede this co-operation. If the amount of effort applied to a task is excessive, the resulting muscle activity is likely to interfere with the reflex by reducing sensitivity. Activation of the reflex could either be delayed or even totally restricted. When the reflex is finally activated, movement is limited due to the reduced capacity of a shortened muscle to contract further or its inability to lengthen when required.

Alexander stressed that if we stop doing the wrong things the right things take care of themselves. If we learn to stop stiffening the neck, the head will ‘find’ its own balance and bring about the most appropriate muscle tone for the current situation to facilitate our innate righting reflexes. As we do not know what the optimum tone should be for each muscle it is not something we should try to achieve. Activities performed with minimal interference with our balance mechanisms will ensure the most appropriate muscle response. Good quality movement promotes the right type of conditioning and removes the need for additional ‘specialist’ exercises.

So how do we attain good movement in order to get into shape? First we need to establish what it is we have been doing to get out of shape, and then we have to learn to stop doing it before we attempt anything else. 

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I have included below a reply from Stuart McGill PhD (Physiology) Dept of Kinesiology, University of Waterloo, Canada in response to my question regarding core stabilisation techniques. He has published over one hundred papers in this area. 

"There is a problem - there are too many therapists promoting stability exercises who do not know what it is, how to measure it, and how to achieve it. Strength has nothing to do with it. Each patient must be properly evaluated to determine the deficit - poor motor patterns or otherwise. I give courses on this and therapists are surprised as to how much is involved- certainly much more than the journals will allow when we publish data based studies. I know the Alexander Technique and in many cases the stable motor patterns are established."
 

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