Ultrasound Characteristics of The Abdominal Muscle Thickness during Prone Hip Extension Test in Subjects with and without Lower Back Pain

Background Deep abdominal muscles have a stabilizing role in the lumbo-pelvic region both increasing intra-abdominal pressure and lateral tension on thoracolumbar fascia. Prone hip extension (PHE) is commonly used as a reliable self-perturbation task to test lumbopelvic stability. To our knowledge, no study has directly evaluated abdominal muscle thickness with and without lower back pain (LBP) using ultrasound measurements during the PHE test. Objectives The purpose of the present study is to investigate the changes in the thickness of the trans-verse abdominis (TrA), internal oblique (IO), and external oblique (EO) during PHE using USI in subjects with and without LBP. Methods Seventy-three subjects (37 with LBP, 36 without LBP) were allocated. Three repeated ultra-sound imaging (USI) measurements were recorded in the prone resting position and during the PHE test in a day. Ultrasonography was used to determine the task-related changes in the thickness of abdominal muscles at resting and during the PHE test. Results The muscle thickness of the TrA and IO in the LBP group was significantly lower compared to without the LBP group during the PHE test (p < 0.05). While, the muscle thickness of the EO in the LBP group was significantly greater compared to without the LBP group during the PHE test (p < 0.05). Conclusions Our findings indicate that Individuals with LBP was lower muscle thickness of TrA and IO and greater muscle thickness of EO compared to the without LBP group. The findings of this study may be useful data for comparing the effects before and after exercise on muscle thickness of TrA, IO, and EO in LBP and planning treatment.