Evidence synthesis showed limited evidence supporting poor baseline transversus abdominis contraction thickness ratio as a treatment effect modifier favoring motor control exercise .
Limited evidence supported that high baseline transversus abdominis lateral slide was associated with higher pain intensity after various exercise interventions at 1-year follow-up .
However , there was limited evidence for the absence of relation between the contraction thickness ratio of transversus abdominis or anticipatory onset of lateral abdominal muscles at baseline and the short- or long-term LBP intensity after exercise interventions .
There was conflicting evidence for a relation between baseline percent thickness change of lumbar multifidus during contraction and the clinical outcomes of patients after various conservative treatments .
Although individual reports suggest that baseline morphometry or activity of transversus abdominis or lumbar multifidus predict clinical outcome of low back pain ( LBP ) , a related systematic review is unavailable .
Therefore , this review summarized evidence regarding the predictive value of these muscular characteristics .
Intra-abdominal pressure increases stiffness of the lumbar spine.
Intra-abdominal pressure ( IAP ) increases during many tasks and has been argued to increase stability and stiffness of the spine . Although several studies have shown a relationship between the IAP increase and spinal stability , it has been impossible to determine whether this augmentation of mechanical support for the spine is due to the increase in IAP or the abdominal muscle activity which contributes to it . The present study determined whether spinal stiffness increased when IAP increased without concurrent activity of the abdominal and back extensor muscles . A sustained increase in IAP was evoked by tetanic stimulation of the phrenic nerves either unilaterally or bilaterally at 20 Hz ( for 5 s ) via percutaneous electrodes in three subjects .  Spinal stiffness was measured as the force required to displace an indentor over the L4 or L2 spinous process with the subjects lying prone . Stiffness was measured as the slope of the regression line fitted to the linear region of the force-displacement curve . Tetanic stimulation of the diaphragm increased IAP by 27 - 61 % of a maximal voluntary pressure increase and increased the stiffness of the spine by 8 - 31 % of resting levels . The increase in spinal stiffness was positively correlated with the size of the IAP increase . IAP increased stiffness at L2 and L4 level . The results of this study provide evidence that the stiffness of the lumbar spine is increased when IAP is elevated
Evidence synthesis showed limited evidence supporting poor baseline transversus abdominis contraction thickness ratio as a treatment effect modifier favoring motor control exercise .
Limited evidence supported that high baseline transversus abdominis lateral slide was associated with higher pain intensity after various exercise interventions at 1-year follow-up .
However , there was limited evidence for the absence of relation between the contraction thickness ratio of transversus abdominis or anticipatory onset of lateral abdominal muscles at baseline and the short- or long-term LBP intensity after exercise interventions .
There was conflicting evidence for a relation between baseline percent thickness change of lumbar multifidus during contraction and the clinical outcomes of patients after various conservative treatments .
Although individual reports suggest that baseline morphometry or activity of transversus abdominis or lumbar multifidus predict clinical outcome of low back pain ( LBP ) , a related systematic review is unavailable .
Therefore , this review summarized evidence regarding the predictive value of these muscular characteristics .