title: Deep abdominal muscle thickness measured under sitting conditions during different stability tasks.
abstract: [Purpose] This study was conducted to investigate ultrasonically determined changes in the thickness of the transversus abdominis and internal oblique muscles during different sitting conditions. [Subjects and Methods] Twenty healthy men volunteered to participate in this study. Four different sitting conditions including (A) sitting, (B) sitting with left hip flexion, (C) sitting with an abdominal hollowing maneuver (AHM), and (D) sitting with an AHM and left hip flexion, were used. Subjective exercise difficulty was evaluated. [Results] Transversus abdominis and internal oblique muscle thicknesses significantly differed between conditions, with significantly greater thickness between positions from (A) to (D). Stability of the surface when sitting had no effect on the muscle thickness of the transversus abdominis. By contrast, sitting on an unstable surface caused an increase in muscle thickness of the internal oblique in each condition. The subjects reported progressively increasing difficulty in performing each exercise in a stable position from (A) to (D), while the difficulty in an unstable position was significantly different between (A) and (B), and between (C) and (D). [Conclusion] Our findings suggest that task (B) on a stable surface should be chosen for maximal activation of transversus abdominis without inducing overactivation of the internal oblique muscle.
authors.affiliation: Saitama Medical Welfare College, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Nagai
authors.affiliation: School of Physical Therapy, Faculty of Health and Medical Care, Saitama Medical University, Japan; Master and Doctoral Program of Medical Sciences in Physical Therapy, Saitama Medical University Graduate School of Medicine, Japan.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Akasaka
authors.affiliation: School of Physical Therapy, Faculty of Health and Medical Care, Saitama Medical University, Japan; Master and Doctoral Program of Medical Sciences in Physical Therapy, Saitama Medical University Graduate School of Medicine, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Otsudo
authors.affiliation: School of Physical Therapy, Faculty of Health and Medical Care, Saitama Medical University, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sawada
authors.affiliation: School of Physical Therapy, Faculty of Health and Medical Care, Saitama Medical University, Japan; Master and Doctoral Program of Medical Sciences in Physical Therapy, Saitama Medical University Graduate School of Medicine, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Okubo
keywords: Abdominal hollowing; Deep abdominal muscles; Ultrasonography