Reproducibility and Concurrent Validity of Manual Palpation with Rehabilitative Ultrasound Imaging for Assessing Deep Abdominal Muscle Activity: Analysis with Preferential Ratios - Valentin-Mazarracin, Irene; Nogaledo-Martin, Miriam; Lopez-de-Uralde-Villanueva, Ibai; Fernandez-de-las-Penas, Cesar; Stokes, Maria; Arias-Buria, Jose L.; Diaz-Arribas, Maria J.; Plaza-Manzano, Gustavo; (Diagnostics, 2021)