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 .
The relationship between EMG and change in thickness of transversus abdominis.
OBJECTIVE To investigate the relationship between changes in thickness and EMG activity  in the transversus abdominis muscle of healthy subjects and the reliability of ultrasound measurements using different modes and transducers . DESIGN Convenience sampling . BACKGROUND Chronic low back pain is associated with transversus abdominis dysfunction but EMG studies of this muscle are restricted to invasive techniques . Since the thickness of transversus abdominis changes with activity , such changes measured from ultrasound images might provide insight into this muscle 's function non-invasively . In addition , little is known about the comparability of ultrasound measurements from different modes and transducers , nor the reliability of transversus abdominis measurements . METHODS In 9 healthy subjects ( aged 29 - 52 years , four male )  transversus abdominis was studied at rest and during activity ( 5 - 80 % max ) with simultaneous EMG and ultrasound ( M mode , 5 MHz curvilinear transducer ) measurements . Intra-rater reliability for thickness measurements was studied on 13 subjects using 7.5 MHz linear and 5 MHz curvilinear transducers in B and M modes . RESULTS Muscle thickness changes correlated well with EMG activity ( P < 0.001 , R2 = 0.87 ) and there were no significant differences between subjects ( P > 0.05 ) . Using 7.5 MHz head , the ICC for B mode was 0.989 and for M mode was 0.981 for between days reliability . The ICC for between transducer reliability was 0.817 . CONCLUSIONS Changes in thickness of transversus abdominis can be used to indicate changes in the electrical activity in this muscle . RELEVANCE Ultrasound scanning can be used in the clinical setting to provide objective information about transversus abdominis function
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 .