Inter-Rater Reliability of Ultra Sound Based Rectus Abdominis Thickness Following Blood Flow Restriction Training

Accurate assessment of skeletal muscle morphology is important in sports physiotherapy, exercise rehabilitation, and research. B-mode ultrasonography is a non-invasive and accessible method for assessing muscle thickness; however, ultrasound-based measurements may be influenced by image acquisition, anatomical landmark identification, and operator-dependent measurement procedures. Establishing inter-rater reliability is therefore essential to determine whether different assessors can obtain consistent measurements of muscle thickness from the same ultrasound images. The rectus abdominis is an important component of the abdominal musculature and contributes to trunk stabilization and functional performance during exercise. Blood flow restriction (BFR) training has gained increasing attention as a low-load exercise strategy for promoting muscular adaptations, although research has predominantly focused on peripheral limb muscles. Therefore, this study aims to evaluate the inter-rater reliability of ultrasound-based rectus abdominis muscle thickness measurements following a standardized BFR training protocol using ImageJ software. Establishing reliable measurement of rectus abdominis thickness will provide a methodological basis for future research investigating abdominal muscle morphology and adaptations in sports physiotherapy, exercise rehabilitation, and BFR-based training.