Ultrasonography of the deep abdominal muscles at rest and during the drawing-in maneuver: A comparative study of Japanese adolescent vs. adult soccer players

Objective: The purpose of this study was to clarify the characteristics of abdominal deep muscles in adolescent soccer players. Methods: Participants were 53 soccer players from junior high school and 14 adult soccer players. The deep abdominal muscles of both sides were imaged by ultrasonography. Abdominal muscles on the dominant leg side were selected as the targets of measurements, and measurements of the transversus abdominis (TrA) and internal oblique (IO) muscle were conducted. The muscle thickness of these muscles was measured at rest and during contraction (while drawing-in of the abdominal wall) and served as the basis for comparing the adolescent and adult players. Results: While no significant inter-group differences were noted in the thickness of the TrA or IO muscle at rest, a significant difference was observed during the drawing-in maneuver. Conclusion: The deep abdominal muscles of adolescent soccer players have not likely reached full maturity.