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Psoas 4

18th February 2014

Koen Schoolmeesters finishes the series on Psoas Major

 

Park R, Tsao H, Cresswell AG, Hodges P,  2013(b), Changes in direction-specific activity of Psoas Major and Quadratus Lumborum in people with recurring back pain differ between muscle regions and patient groups,  Journal of electromyography and kinesiology 23 :734-740

 

People with recurring back pain - Changes in direction-specific activity of Psoas Major


The findings of this study support the hypothesis of “Adaptation of motor control in pain” (Hodges 2011). This means that the nervous system increases, decreases or redistributes activity within and/or between muscles in the presence/threat of pain.  


In individuals with less Erector Spinae activity in an upright lumbar posture (uncontrolled lumbar flexion), Posterior Psoas and Anterior Psoas have a tendency towards greater activation during extension torque production. This may reflect an attempt by the nervous system to compensate for the decreased trunk Erector Spinae extensor torque in this group in sitting.  Deep trunk muscles are favoured over Erector Spinae in this subgroup to achieve the same task.  


In individuals with high Erector Spinae activity in an upright position (uncontrolled lumbar extension), Posterior Psoas and Anterior Psoas activity is less biased to extension during a task that requires extension torque production but mainly biased to lateral flexion. Another interpretation is that Erector Spinae is preferentially recruited to substitute for limitation of contribution by Psoas Major to postural control.


This strategy of direction preference of Psoas Major activity according to the LBP subgroup, is beneficial in the short term to change load distribution and to protect the spine from pain or injury but could be detrimental in the long term.  E.g. Less bias of Psoas Major towards trunk extension in the LBP- subgroup with uncontrolled extension may hinder the segmental control of the lumbar spine and could contribute in recurrence of LBP.



Hodges P, 2011, Pain and motor control : from the laboratory  to rehabilitation, Journal of electromyography and kinesiology 21 : 220-228

Keywords: Review 2014