In the lumbar spine, lateral flexion to one side is accompanied by rotation to the opposite side (likely due to the locked-short transversospinalis
musculature on the side of concavity).
 found low but a statistically significant negative correlation between paraspinal muscle density and body mass index (BMI) (r = -0.193, p = 0.009 in transversospinalis
and r = -0.251, p = 0.001 in erector spinae).
Thus, the muscle chain of the external oblique muscle from one part continues with the fiber direction of the internal oblique from the opposite side and in the back side of the trunk it continues with the transversospinalis
system on the same side (Nenciu, 2005).
Low back muscles: The erector spinae group (spinalis longissimus and iliocostalis), the transversospinalis
group (multifidi, rotators, and semispinalis), and the quadratus lumborum, comprise the posterior extrinsic and intrinsic support groups.
Therefore the target muscles to which treatment must be directed are the pectoral muscles anteriorly (pectoralis major, pectoralis minor, and the subclavius), and the posterior muscles of thoracic-spinal extension (erector spinae and transversospinalis
), shoulder girdle retraction (rhomboids and trapezius, especially middle trapezius), and humeral medial rotation (subscapularis, teres major, latissimus dorsi, anterior deltoid, and pectoralis major).
Low Back: The erector spinae group (spinalis, longissimus, and iliocostalis), the transversospinalis
group (multifidi, rotatores, and semispinalis), and the quadratus, lumborum, are important muscles in this area.
Unfortunately, many therapists bend at the spine, creating a stooped and imbalanced posture that is unhealthy for the spinal joints because they are in an unstable open-packed position, and unhealthy for the paraspinal (erector spinae and transversospinalis
) extensor musculature because it must contract to prevent the trunk from falling into flexion (Figure 4A).
The following muscles may be found to be lengthened and taut/tight: rhomboids, middle and lower trapezius, serratus anterior, longus colli and capitis, infraspinatus and teres minor, and thoracic paraspinals (erector spinae and transversospinalis
Flexion has another positive effect: It stretches all posterior tissues of the spine, including the paraspinal (erector spinae and transversospinalis
Trunk extensors such as the multifidus of the transversospinalis
group and erector spinae are often tight due to loads placed on them when bending forward: eccentric loads when flexing forward, isometric loads maintaining a bent-forward posture, and eccentric loads when returning to erect position.