Effects of Transverse Abdominis Activation and Rectus Abdominis Strengthening on Inter-rectus Distance and Core Stability

Effects of Transverse Abdominis Activation and Rectus Abdominis Strengthening on Inter-rectus Distance and Core Stability Among Patients With Diastasis Rectus Abdominis

This randomized controlled trial aims to compare the effects of Transverse Abdominis (TrA) activation, Rectus Abdominis (RA) strengthening, and their combined approach on inter-rectus distance (IRD) and core stability in postpartum women diagnosed with diastasis rectus abdominis (DRA). Thirty-three participants will be randomly allocated into three groups and will complete a six-week exercise program at the Pakistan Society for the Rehabilitation of the Disabled (PSRD) Hospital, Lahore. The study will use real-time ultrasound and pressure biofeedback assessment to evaluate changes in IRD and core stability. It is hypothesized that TrA activation and the combined intervention will produce greater improvements compared to RA strengthening alone.

Background and Rationale:

Diastasis Rectus Abdominis (DRA) is a prevalent postpartum musculoskeletal condition characterized by the separation of the rectus abdominis muscles along the linea alba, resulting in impaired trunk stability, abdominal weakness, and postural dysfunction. Despite its high prevalence, DRA remains underdiagnosed and undertreated, particularly in developing countries where structured rehabilitation protocols are lacking. Physiotherapy-based interventions focusing on abdominal muscle retraining and core stability have been shown to improve outcomes; however, the relative effectiveness of Transverse Abdominis (TrA) activation, Rectus Abdominis (RA) strengthening, and their combined approach remains uncertain.

Objectives:

This randomized controlled trial aims to compare the effects of TrA activation, RA strengthening, and their combination on inter-rectus distance (IRD) and core stability among postpartum women with DRA.

Methods:

This three-arm, parallel-group randomized controlled trial will be conducted at the Pakistan Society for the Rehabilitation of the Disabled (PSRD) Hospital, Lahore, Pakistan. A total of 33 postpartum women aged 20-40 years, diagnosed with DRA (6 months to 2 years postpartum), will be recruited using non-probability convenience sampling. Participants will be randomly assigned into three groups (n = 11 per group):

Group A (TAA): Transverse Abdominis Activation exercises

Group B (RAS): Rectus Abdominis Strengthening exercises

Group C (TAA + RAS): Combined TrA activation and RA strengthening protocol

Each participant will undergo a 6-week intervention program, including three supervised sessions per week for 3 weeks, followed by a 3-week home exercise program. Each session will last 30-45 minutes and will be supervised by a licensed physical therapist at PSRD.

Outcome Measures:

Primary Outcome: Change in Inter-Rectus Distance (IRD), measured via real-time ultrasound imaging (7.5 MHz linear probe) at three anatomical sites (4.5 cm above, at, and 4.5 cm below the umbilicus), pre- and post-intervention.

Secondary Outcome: Core stability, assessed using a Pressure Biofeedback Unit (PBU) during the abdominal drawing-in maneuver (ADIM) in crook-lying position. Participants will aim to reduce pressure by 6-10 mmHg from a 40 mmHg baseline and sustain the contraction for 10 seconds; the mean of three trials will be recorded.

Randomization and Blinding:

Participants will be randomized using Randomized Allocation Software (Version 1.0) in a 1:1:1 ratio. Due to the exercise-based nature of the interventions, blinding of participants and therapists is not feasible; however, the outcome assessor will remain blinded to group assignments, ensuring a single-blind design.

Data Analysis:

Statistical analysis will be performed using SPSS version 26. Data will first be tested for normality using the Shapiro-Wilk test. A two-way mixed ANOVA will be applied to assess both within-subject effects (time: pre vs. post) and between-subject effects (group: TAA, RAS, TAA+RAS), as well as the interaction effect (time × group) on IRD and core stability outcomes. Post-hoc pairwise comparisons with Bonferroni correction will identify specific between-group differences. Statistical significance will be set at p < 0.05 with a 95% confidence interval.

Expected Clinical Significance:

It is hypothesized that TrA activation exercises will lead to a greater reduction in IRD and improvement in core stability compared to RA strengthening alone. The combined exercise group (TAA + RAS) is expected to demonstrate the most comprehensive benefits due to synergistic activation of both deep and superficial abdominal muscles. The study outcomes are anticipated to provide evidence-based guidance for physiotherapists in postpartum rehabilitation, contributing to the development of standardized, non-invasive exercise protocols for DRA management and improved quality of life in postpartum women.

Inclusion Criteria:

. Postpartum women diagnosed with DRA

• Multigravida
• Delivered a singleton pregnancy via vaginal breech or instrumental delivery

Exclusion Criteria:

. Pregnancy

• Abdominal and pelvic hernias or severe musculoskeletal conditions
• Patients with abdominal and pelvic surgery
• Patients with disc herniation