Changes in external ischial tuberosity width at varying trunk-thigh angles between sexes using two measurement...

Area of Science:

• Biomechanics
• Ergonomics
• Anthropometry

Background:

• External ischial tuberosity width (EITW) is a critical anthropometric measure for seating design.
• Understanding how measurement methods and body positioning affect EITW is essential for accurate ergonomic assessments.

Purpose of the Study:

• To investigate the influence of two measurement methods (impress and seat pressure) and various trunk-thigh (TT) angles on EITW.
• To determine gender-specific differences in EITW and their implications for seat cushion design.

Main Methods:

• The study involved 90 participants (45 men, 45 women).
• External ischial tuberosity width (EITW) was measured using the impress and seat pressure methods at TT angles of 60°, 75°, 90°, and 105°.
• Correlation analyses were performed between EITW and hip dimensions (circumference, width, depth).

Main Results:

• The impress method showed minimal variation in EITW across TT angles (2.8 mm men, 2.1 mm women).
• The seat pressure method revealed significant increases in EITW with rising TT angles (11.5 mm men, 11.7 mm women).
• Gender differences in EITW were substantial (12.6–13.7 mm) across all conditions. Hip circumference positively correlated with EITW.

Conclusions:

• Measurement method and trunk-thigh angle critically influence EITW readings.
• Significant gender-based differences in EITW exist.
• Seat cushion design must account for gender variability in EITW for optimal ergonomics.