The Relationship of Transversus Abdominis and Lumbar Multifidus Activation and Prognostic Factors for Clinical Success With a Stabilization Exercise Program: A Cross-Sectional Study

Abstract

Hebert JJ, Koppenhaver SL, Magel JS, Fritz JM. The relationship of transversus abdominis and lumbar multifidus activation and prognostic factors for clinical success with a stabilization exercise program: a cross-sectional study. Objective To examine the relationship between prognostic factors for clinical success with a stabilization exercise program and lumbar multifidus (LM) and transversus abdominis (TrA) muscle activation assessed using rehabilitative ultrasound imaging (RUSI). Design Cross-sectional study. Setting Outpatient physical therapy clinic. Participants Volunteers with current low back pain (N=40). Intervention Not applicable. Main Outcome Measures We examined the relationship between prognostic factors associated with clinical success with a stabilization exercise program (positive prone instability test, age <40y, aberrant movements, straight leg raise >91°, presence of lumbar hypermobility) and degree of TrA and LM muscle activation assessed by RUSI. Results Significant univariate relationships were identified between LM muscle activation and the number of prognostic factors present (Pearson correlation coefficient [ r] =−.558, P=.001), as well as the individual factors of a positive prone instability test (point biserial correlation coefficient [ r pbis ]=.376, P=.018) and segmental hypermobility ( r pbis =.358, P=.025). The multivariate analyses indicated that after controlling for other variables, the addition of the variable “number of prognostic factors present” resulted in a significant increase in R 2 ( P=.006). No significant univariate or multivariate relationships were observed between the prognostic factors and TrA muscle activation. Conclusions Decreased LM muscle activation, but not TrA muscle activation, is associated with the presence of factors predictive of clinical success with a stabilization exercise program. Our findings provide researchers and clinicians with evidence regarding the construct validity of the prognostic factors examined in this study, as well as the potential clinical importance of the LM muscle as a target for stabilization exercises.