Wednesday 16th May 2018

Latent (pain free) trigger points shown to cause rapid fatigue with pain-and underlie many other issues

Summary

A study published in the journal Pain Medicine 2011 found that muscles containing latent (pain free) trigger points fatigued quickly and became painful.  This is not surprising considering a trigger point is part of a muscle constantly in a hyper-contracted state, and already suffering from local hypoxia and a build up of metabolites.  Any time there is pain and fatigue following prolonged postures or repeated exertions latent trigger points should be a prime consideration.   This is especially true when considering the high prevalence of latent trigger points, and that aggravations such as overloading or even a change in temperature can transform a latent trigger point into an active (pain producing) trigger point creating a chronic pain syndrome.

In addition, the researchers found that when latent trigger points were present the nervous system quickly recruits adjoining muscle fibres and muscles to assist.  The altered control of muscles in the presence of latent trigger points has also been shown in previously summarised research.  Because of this altered control, the rapid fatigue and characteristic tightness of muscles with latent trigger points, latent trigger points have a further far-reaching role in postural changes and biomechanical dysfunction.  This in turn can underlie a lot of pain syndromes, injuries and joint degeneration.

The basics

The role of the central nervous system
Movement and posture are guided by conscious thought but are largely under subconscious control.  For example, one may consciously choose to stand.  However, the central nervous system uses pre-programmed instructions combined with feedback from sensors such as those in the muscles, connective tissues and joints to co-ordinate the muscle activity to produce this goal.  It is likewise when making practically any movement or doing any activity.

Optimum movement and posture

Optimum posture is where a balance is achieved: minimising tension on muscles and stress on connective tissues, while maintaining even pressure on the joint surfaces.  The central nervous system is continually monitoring these aspects and making appropriate adjustments.  Likewise, optimal movement is where mechanical advantages are maximised and stress on the muscles, connective tissues and joints is minimised.  Again, the central nervous system is monitoring these aspects in order to make the appropriate muscle activations.

Dysfunction

When we have a deviation from optimal posture or biomechanics there is an increase in muscle tension and stress upon connective tissues. Also, pressure is distributed less evenly across joint surfaces.  This can lead to pain syndromes, an increased risk of injury and accelerated degeneration.

Why do we get dysfunction?

Some dysfunction may be habitual or learned, but much is due to adaptations made by the central nervous system as it adjusts or compensates.  Let us consider a simple example- when a latent trigger point affects a postural muscle.  A characteristic of such a muscle would be tightening.   The central nervous system would detect this tightening and make adjustments to compensate, probably tilting slightly towards the affected muscle.  This would in turn alter the balance along with increasing the tension on other muscles and stress on connective tissues and joints.  The central nervous system would make the best adjustments it could given the abnormal situation.

The research showed that muscles containing latent trigger points fatigued quickly and became painful.  The central nervous system would detect this and make appropriate changes.  Likewise, articular dysfunction as described elsewhere would create sensory feedback also resulting in the central nervous system making compensations.   There would be added stress elsewhere, but it would be the best the central nervous system could do in the circumstances.  Of course the muscles, connective tissues and joints forced to compensate may then over time develop their own issues forcing further compensations, creating a chain of changes increasingly more complex and chronic issues.

The central nervous system in action

In this research electrodes placed to pick up nerve signals showed that when latent trigger points were present signals were quickly sent to adjoining muscles in an effort to have them assisted.  In previously summarised research such electrodes were used to detect the controlled activity of muscles used when lifting an arm to the side.  It was shown that when latent trigger points were present the order and timing of the muscle activation completely changed, resulting in abnormal movement and un-coordinated joint control.

Clinical implications

  1. Latent trigger points (and articular dysfunction) are highly prevalent.  They cause abnormal posture and biomechanical dysfunction, which are behind a vast array of musculoskeletal complaints.  They should always be considered.
  2. There will always be times when corrective exercises and other corrective measures are needed.  However, one should always consider whether the posture or function that needs correcting is a compensation produced by the central nervous system as a result of something abnormal.  It makes no sense trying to artificially correct such an issue without correcting the underlying cause if possible.  The recommended approach would be to eliminate the causes of compensation, allow the central nervous system to re-adjust, and assist where necessary.
  3. As shown in previously summarised research though the transformation of active trigger points from active to latent (providing symptomatic relief) can sometimes be quick, the successful elimination of trigger points can require a large number of applications of therapy over time.  This is one of the main reasons we built or massagers.  They make it easier for practitioners, plus allow the option of practically unlimited supplementary self applications of therapy under the advice of a qualified professional.

Reference

Ge HY1, Arendt-Nielsen L, Madeleine P.  Accelerated muscle fatigability of latent myofascial trigger points in humans. Pain Med. 2012 Jul;13(7):957-64

Samples and practitioner orders

We happily supply sample massagers to degree qualified practitioners who deal with musculoskeletal complaints, on a one per clinic basis.  Please email us directly on graeme@drgraeme.com for samples or practitioner/wholesale supply.

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About Dr Graeme

Several years ago Dr Graeme, a Chiropractor practicing in Victoria, Australia was looking for a serious hand held massager his patients could use at home to get the extra quality massage they needed. The ones he found in the shops and on-line for home use looked nice but were not serious, and ... read more