Localised reflexively active structures (myofascial trigger points) will emerge in the highly stressed,ischaemic, tissues, and these become responsible for the development of new dysfunction at distant target sites, typically inhibiting antagonist muscles.
Because of excessive hypertonic activity there will be energy wastage and a tendency to fatigue - both locally and generally.
Functional imbalances will occur, for example involving respiratory function, when chain reactions of hypertonicity and weakness impact this. ,
Muscles become involved in ‘chain-reactions’ of dysfunction as some muscles are used inappropriately as they compensate for other structures which are weak or restricted, leading to a loss loss of their ability to act synergistically or normally.
Over time the central nervous system accepts altered use patterns, as normal, complicating recovery since rehabilitation then requires a relearning process as well as more obvious structural and functional muscle and joint corrections.
Understanding Muscles
In order to make sense of patterns of soft tissue change it is necessary to conceptualise muscular function and dysfunction as being something other than a local event.
Irwin Korr stated the position elegantly and eloquently:
‘The spinal cord is the keyboard on which the brain plays when it calls for activity. But each ‘key’ in the console sounds not an individual ‘tone’ such as the contraction of a particular group of muscle fibres, but a whole ‘symphony’ of motion. In other words, built into the cord is a large repertoire of patterns of activity, each involving the complex, harmonious, delicately balanced orchestration of the contractions and relaxation of many muscles.The brain thinks in terms of whole motions, not individual muscles. It calls,selectively, for the preprogrammed patterns in the cord and brain stem, modifying them in countless ways and combining them in an infinite variety is still more complex patterns. Each activity is subject to further modulation refinement, and adjustment by the feedback continually streaming in from the participating muscles, tendons and joints.’
We must never forget the complex interrelationships between the soft tissues, the muscles, fascia and tendons and their armies of neural reporting stations, as we attempt to understand the nature of dysfunction and of what is required to achieve normalisation.
Postural Muscles - a factor to keep in mind
Research by Lewit, Korr, Janda, Basmajian, and others shows that muscles which have predominantly stabilising functions will shorten when stressed while others which have more active ‘moving’ or phasic functions will not shorten but will become weak (inhibited).
The muscles which shorten are those which have a primarily postural rather than phasic (active, moving) role and it is possible to learn to conduct, in a short space of time (ten minutes or so) an assessment sequence in which the majority of these can be identified as being either short or normal.
Janda informs us that postural muscles have a tendency to shorten, not only under pathological conditions but often under normal circumstances. He has noted, using electromyographic instrumentation, that 85 per cent of the walking cycle is spent on one leg or the other, and that this is the most common postural position for man. Those muscles which enable this position to be satisfactorily adopted (one-legged standing) are genetically older; they have different physiological, and probably biochemical, qualities compared with phasic muscles which normally weaken and exhibit signs of inhibition in response to stress or pathology.