Study design: Randomized controlled trial among patients with low back pain (LBP).
Objectives: (1) Determine the reliability of real-time ultrasound imaging for assessing activation of the lateral abdominal muscles; (2) characterize the extent to which the abdominal drawing-in maneuver (ADIM) results in preferential activation of the transverse abdominis (TrA); and (3) determine if ultrasound biofeedback improves short-term performance of the ADIM in patients with LBP.
Background: Ultrasound imaging is reportedly useful for measuring and training patients to preferentially activate the TrA muscle. However, research to support these claims is limited.
Methods and measures: Thirty patients with LBP referred for lumbar stabilization training were randomized to receive either traditional training (n = 15) or traditional training with biofeedback (n = 15). Ultrasound imaging was used to measure changes in thickness of the lateral abdominal muscles. Differences in preferential changes in muscle thickness of the TrA between groups and across time were assessed using analysis of variance.
Results: Intrarater reliability measuring lateral abdominal muscle thickness exceeded 0.93. On average, patients in both groups demonstrated a 2-fold increase in the thickness of the TrA during the ADIM. Performance of the ADIM did not differ between the groups.
Conclusion: These data provide construct validity for the notion that the ADIM results in preferential activation of the TrA in patients with LBP. Although, the addition of biofeedback did not enhance the ability to perform the ADIM at a short-term follow-up, our data suggest a possible ceiling effect or an insufficient training stimulus. Further research is necessary to determine if there is a subgroup of patients with LBP who may benefit from biofeedback.