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 .
Experimental muscle pain changes feedforward postural responses of the trunk muscles
Many studies have identified changes in trunk muscle recruitment in clinical low back pain ( LBP ) . However , due to the heterogeneity of the LBP population these changes have been variable and it has been impossible to identify a cause-effect relationship . Several studies have identified a consistent change in the feedforward postural response of transversus abdominis ( TrA ) , the deepest abdominal muscle , in association with arm movements in chronic LBP . This study aim ed to determine whether the feedforward recruitment of the trunk muscles in a postural task could be altered by acute experimentally induced LBP .  Electromyographic ( EMG ) recordings of the abdominal and paraspinal muscles were made during arm movements in a control trial , following the injection of isotonic ( non-painful ) and hypertonic ( painful ) saline into the longissimus muscle at L4 , and during a 1-h follow-up . Movements included rapid arm flexion in response to a light and repetitive arm flexion-extension . Temporal and spatial EMG parameters were measured . The onset and amplitude of EMG of most muscles was changed in a variable manner during the period of experimentally induced pain . However , across movement trials and subjects the activation of TrA was consistently reduced in amplitude or delayed . Analyses in the time and frequency domain were used to confirm these findings . The results suggest that acute experimentally induced pain may affect feedforward postural activity of the trunk muscles . Although the response was variable , pain produced differential changes in the motor control of the trunk muscles , with consistent impairment of TrA activity
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 .