Reliability and Validity of Transversus Abdominis Measurement at the Posterior Muscle-Fascia Junction with Ultrasonography in Asymptomatic Participants.

OBJECTIVE: The purposes of this study were (1) to establish the intrarater sliding and change in thickness of the transversus abdominis (TrA) measurement at the posterior muscle-fascia junction and (2) to examine the relationship between the muscle thickness and sliding of the TrA at the anterior and posterior sites. METHODS: Asymptomatic participants (n = 20) were placed into the hook-lying position to perform the abdominal drawing-in maneuver viewed in B-mode with a 5- to 12-MHz linear ultrasound transducer. The outcome variables included the resting thickness, the thickness during contraction, the change of thickness, and the change of sliding length. Both intraclass correlation coefficient and Pearson correlation were used for analysis. RESULTS: Measuring the thickness and sliding of the TrA at the posterior muscle-fascia junction showed good reliability (intraclass correlation coefficient (3,3), 0.89-0.98). The correlations between the sliding measurements of the TrA at the anterior and posterior sites were moderate to good (r = 0.41-0.74). CONCLUSION: This study found that measuring the musculofascial corset from the posterior site using ultrasonography is reliable, allowing for ultrasound measurements at both the anterior and posterior sites of the TrA to provide a comprehensive evaluation of the TrA fascia.