The erector spinae muscle group, or also known as lumbar extensors, consists of 3 muscles: spinalis (medial), longissimus (central) and illiocostalis (lateral), extending vertically up the back starting near the sacrum, lying on each side of the vertebral column ((Erector spinae, 2022). Spinalis and longissimus are each further split into capitis, cervicis, and thorasis, while illiocostalis is split into cervicis, thoracis and lumborum.
The erector spinae muscles contract eccentrically during flexion. And in full flexion of the trunk, the erector spinae myoelectric activity is decreased or silenced. This is known as flexion-relaxation phenomenon/response and this response is important in helping individuals to achieve full spinal flexion such as in uttanasana (standing forward bend) and paschimottanasana (seated intense forward bend).
Such a response is usually not found in individuals with chronic low back pain (Nougarou, Massicotte & Descarreaux, 2012). But, for individuals with no low back pain, there could also be asymmetric trunk flexion if their daily activities or postures are asymmetrical. And such an asymmetric trunk flexion leads to asymmetric flexion-relaxation response which subsequently increases the chances of suffering low back pain.
Lumbar stabilization exercises can help individuals to restore this response and aids in reducing lower back pain through the strengthening the deep back and abdominal muscles such as transversus abdominis, oblique abdominals, quadratus lumborum or multifidus.
To strengthen quadratus lumborum, individuals may practice asanas such as sethu bandasana (bridge pose), utkatasana (chair pose), marjaryasana-bitilasana (cat cow pose), navasana (boat pose), santolasana (plank pose), and ardho mukha swanasana (downward facing dog pose).
To strengthen transversus abdominis, individuals may practice asanas such as chaturanga dandasana (4-limbed staff pose), navasana (boat pose) or virabhadrasana 3 (warrior 3 pose).
To strengthen oblique abdominals, one may practice asanas such as vasisthasana (side plank pose). And for multifidus, individuals may practice parsva balasana (bird dog pose).