Deep abdominal muscle thickness measured under sitting conditions during different stability tasks

Area of Science:

• Kinesiology
• Biomechanics
• Musculoskeletal Ultrasound

Background:

• Core muscle activation is crucial for spinal stability.
• Understanding muscle recruitment during different postures informs exercise prescription.
• The transversus abdominis and internal oblique muscles play key roles in core stability.

Purpose of the Study:

• To ultrasonically assess changes in transversus abdominis and internal oblique muscle thickness.
• To compare muscle activation under various sitting conditions.
• To identify optimal sitting postures for targeted core muscle engagement.

Main Methods:

• Twenty healthy males participated.
• Ultrasound imaging was used to measure muscle thickness.
• Four sitting conditions were tested: sitting, sitting with left hip flexion, abdominal hollowing maneuver (AHM), and AHM with left hip flexion, on both stable and unstable surfaces.

Main Results:

• Significant differences in transversus abdominis and internal oblique muscle thickness were observed across conditions.
• Sitting with left hip flexion (task B) showed maximal transversus abdominis activation.
• Unstable surfaces increased internal oblique muscle thickness.
• Exercise difficulty increased progressively from condition A to D on stable surfaces.

Conclusions:

• Sitting with left hip flexion on a stable surface is recommended for maximal transversus abdominis activation.
• This posture avoids overactivation of the internal oblique muscles.
• Findings provide guidance for selecting exercises to target specific core muscles effectively.