A novel goniometer method for representing perceived standing position in the anteroposterior direction

This study evaluated the consistency of the 'Goniometer Method' for expressing standing positions in the anteroposterior direction (SPAP) using perceived body tilt angle. We defined the 'Expressed Body Tilt Angle' (perceived posture self-expressed using a goniometer) and the 'Actual Body Tilt Angle' (calculated from images). Regression analysis evaluated relationships between SPAP and the Expressed Body Tilt Angle, SPAP and the Actual Body Tilt Angle, and between the two angles. Coefficients of determination (<i>R</i>²) were calculated for pooled data and as median values for individuals. All relationships showed significant linear correlations, with median individual<i>R</i>²values exceeding pooled<i>R</i>²values. Analysis of covariance comparing subjects with the largest and smallest regression slopes revealed significant inter-individual differences. Pearson's correlation and paired<i>t</i>-tests calculated vertical position and quiet standing position showed a significant correlation but no significant difference. No significant relationship was found between SPAP and the error between Expressed and Actual Body Tilt Angles. In summary, the goniometer method demonstrated a stable linear relationship between body tilt angle and SPAP, although individual variability exists. This relationship remains consistent across SPAP conditions.