Differences in Linea Alba Stiffness and Linea Alba Distortion Between Women With and Without Diastasis Recti Abdominis: The Impact of Measurement Site and Task

Abstract

Background: The biomechanical implications of diastasis recti abdominis (DRA) are unknown.

Objectives: To (1) investigate the impact of DRA, measurement site, and task on inter-rectus distance (IRD), linea alba (LA) stiffness, and LA distortion measured at rest and during head-lift and semi-curl-up tasks; and (2) describe the relationships among IRD, LA stiffness, and LA distortion.

Methods: In this cross-sectional, observational cohort study, brightness-mode ultrasound imaging and shearwave elastography were used on a sample of 20 women. Inter-rectus distance, LA stiffness, and LA distortion were measured at 3 locations, while at rest and during head-lift and semi-curl-up maneuvers. All outcomes were compared between groups (DRA versus no DRA), sites, and tasks. Linear regression models were used to evaluate the relationships among IRD, mean and peak LA stiffness, and LA distortion.

Results: Eleven women with and 9 without DRA participated. Women with DRA demonstrated lower peak and mean LA stiffness and higher LA distortion compared to women without DRA. In women with DRA, IRD and LA distortion were not influenced by measurement site; IRD decreased, LA distortion increased, and LA stiffness did not change during the head lift and semi-curl-up compared to rest. In women without DRA, the LA was least stiff closest to the umbilicus; it increased in stiffness during the head lift and semi-curl-up and did not distort or change compared to rest.

Conclusion: Diastasis recti abdominis was associated with low LA stiffness and with LA distortion during a semi-curl-up task; the amount of distortion was a function of IRD and LA stiffness. J Orthop Sports Phys Ther 2019;49(9):656-665. Epub 26 Mar 2019. doi:10.2519/jospt.2019.8543.

Keywords: inter-rectus distance; linea alba; shearwave elastography; ultrasound imaging.