Interinnominate motion and symmetry: comparison between gymnasts and nongymnasts

Area of Science:

• Biomechanics
• Anatomy
• Kinesiology

Background:

• Clinical treatments for low back pain often focus on pelvic posture and motion asymmetries.
• Existing research indicates limited and variable motion between the innominate bones.

Purpose of the Study:

• To evaluate interinnominate motion symmetry in individuals without low back pain across various postures.
• To assess innominate bone symmetry in a standing position.
• To compare interinnominate motion magnitude between a flexibility-focused group (gymnasts) and the general population.

Main Methods:

• Thirty-four subjects (gymnasts and non-gymnasts) were assessed in standing and three reciprocal postures.
• The Metrecom Skeletal Analysis System captured iliac spine coordinates.
• Projection angles determined the relative positions of the right and left innominate bones.

Main Results:

• Symmetry was observed in modified standing postures but asymmetry in modified sitting postures.
• Half-kneeling postures showed mixed symmetry depending on the subject group.
• Gymnasts displayed asymmetrical innominate bone positioning, while non-gymnasts showed symmetrical positioning.

Conclusions:

• Innominate bone symmetry varies across different postures and between athletic and non-athletic populations.
• Clinical assessments of pelvic asymmetry should consider the specific postures evaluated.
• Differences in innominate bone positioning may relate to flexibility training.