The muscles which shorten are the primarily postural ones and it is possible to learn to conduct, in a short space of time (ten minutes or so) a diagnostic sequence of simple tests in which these can be identified as being short/contracted or normal.
Those muscles which respond to stress by shortening comprise the following :
Gastrocnemius, soleus, medial hamstrings, short adductors of the thigh, hamstrings, psoas, piriformis, tensor fascia lata, quadratus lumborum, erector spinae muscles, latissimus dorsi, upper trapezius, scalenes, sternomastoid, levator scapulae, pectoralis major and the flexors of the arms.
Once any of these is identified as being short (as mentioned, a rapid screening of all is possible and desirable) there exist a powerful range of easily applied methods which allows them to be painlessly stretched back to a more normal state.
This is called 'Muscle Energy Technique'.
Muscle Energy Methods
The following methods are suggested for use in any shortened soft tissue as long as the starting point is at the restriction barrier (for acute conditions) or short of it (for more chronic conditions).
Note: Restriction barrier in this and all other instances is defined as the first signs of resistance as the muscle is taken towards its end of range, not the furthest position obtainable.
Starting from the appropriate position, based on degree of acuteness or chronicity, the patient is asked to exert a small effort AWAY from the restriction barrier (20% of available strength say) towards an unyielding resistance provided by the operator's hands.
This effectively isometrically contracts the shortened muscle(s) and this contraction is held for 7 to 10 seconds (longer, up to 30 seconds, if the condition is chronic) together with a held breath (if appropriate).
On slow release of the contraction the shortened muscle is taken (painlessly) to its new restriction barrier if acute or slightly and painlessly beyond the new barrier if chronic (and if chronic, held there for 7 to 10 seconds in slight stretch).
This pattern is repeated until no further gain in length is achieved.
Alternatively the antagonists to the short muscles can be used by introducing a resisted effort TOWARDS the restriction barrier followed by a painless stretch to the new barrier (acute) or beyond it (chronic).
Use of antagonists in this way is less effective than use of agonist but may be a useful strategy of trauma has taken place.
As an example of what one 'trouble-maker' postural muscle can do we can examine psoas.