Changes in Transversus Abdominis Thickness With Use of the Abdominal Drawing-In Maneuver During a Functional Task

Objective: The purpose of this study was to examine an individual's ability to produce an increase in transversus abdominis (TrA) thickness during the performance of a functional task with the use of the abdominal drawing-in maneuver (ADIM). Design: Within-subject repeated measures analysis of variance was used to examine the effects of the ADIM and a loaded forward-reaching activity on the dependent variable of TrA thickness. Setting: Laboratory Participants: Convenience sample of 8 women and 8 men, asymptomatic, with a mean age of 27.6 +/- 7.1 years. Interventions: Ultrasound imaging measurements were recorded during 4 conditions: (1) while the patient was standing without the ADIM; (2) while the patient was standing with the ADIM; (3) during a loaded forward-reaching activity without the ADIM; and (4) during a loaded forward-reaching activity with the ADIM. Main Outcome Measures: Thickness of the TrA muscle. Results: The measurement obtained by an investigator blinded to the condition revealed statistically significant differences in the thickness of the TrA between all uncontracted conditions as compared with all contracted conditions. No statistically significant difference in the thickness of the TrA in the contracted states during quiet standing versus loaded forward reach was observed. Conclusion: Subjects in this study demonstrated the ability to voluntarily activate the TrA during upright static and functional tasks. Additionally, the TrA thickness may change in a direction-specific manner. These findings support a protective role of the ADIM during functional activity and may add information to ways for promoting low back pain prevention. Future studies should include the effectiveness in the use of ADIM during functional tasks for the prevention of low back pain. PM R 2010;2:187-194