Fibre typing of the back muscles
It has been thought, that the back muscles mostly consist of type 1 muscle fibres, to maintain an upright position. However, the back muscles also have to function as movement muscles.
The back muscles can be divided into global and local muscles and deep or superficial; the thoracic erector spinae has been considered a global muscle, whereas the lumbar erector spinae and multifidus have been considered local muscles. There is also a functional differentiation between these muscles into deep and superficial muscle layers. It has been suggested that there is a difference in fibre typing of these muscles.
It has previously been argued that the type 1 fibre is to be more affected by pain and immobilization than type 2 fibres.
The purpose of this study was to review the available evidence in the literature comparing muscle fibre typing in the back muscles in healthy individuals with patients suffering from low back pain (LBP).
Most of the articles only investigated lumbar muscle fibre types (difference between deep and superficial muscles). The findings between the articles are divergent. Back muscles of healthy individuals had a type 1 percentage ranging from 54%-74,3% and type 2 from 16,4%-30,2%. In the thoracic muscles, there is a higher percentage of type 1 fibres.
There is contradiction about the percentage of fibres in the longissimus and iliocostalis muscles. It has been suggested that the longissimus muscle has more type 1 fibres, however there have also been studies that suggest that there is no difference. More research is necessary in order to come to a definitive conclusion in this matter.
This systematic review found no significant differences in lumbar muscles between healthy patients and LBP patients of the deep or superficial layers of the multifidus or longissimus muscles.
This article provides us with new insights, however it is still unclear what the exact functions are and more research on this topic is necessary.
> From: Cagnie et al., J Manipulative Physiol Ther 38 (2016) 653-663(Epub ahead of print). All rights reserved to National University of Health Sciences. Click here for the Pubmed summary.