Gender differences in pelvic motions and center of mass displacement during walking: stereotypes quantified.

OBJECTIVES A general perception that women and men walk differently has yet to be supported by quantitative walking (gait) studies, which have found more similarities than differences. Never previously examined, however, are pelvic and center of mass (COM) motions. We hypothesize the presence of gender differences in both pelvic obliquity (motion of the pelvis in the coronal plane) and vertical COM displacement. Quantifiable differences may have clinical as well as biomechanical importance. METHODS We tested 120 subjects separated into four groups by age and gender. Pelvic motions and COM displacements were recorded using a 3-D motion analysis system and averaged over three walking trials at comfortable walking speed. Data were plotted, and temporal values, pelvic angle ranges, and COM displacements normalized for leg length were quantitatively compared among groups. RESULTS Comparing all women to all men, women exhibited significantly more pelvic obliquity range (mean ISD): 9.4 +/- 3.5 degrees for women and 7.4 +/- 3.4 degrees for men (p = 0.0024), and less vertical COM displacement: 3.7 +/- 0.8% of leg length for women and 3.3 +/- 0.9% for men (p = 0.0056). CONCLUSIONS Stereotypically based gender differences were documented with greater pelvic obliquity and less vertical COM displacement in women compared with men. It is unclear if these differences are the intrinsic result of gender vs. social or cultural effects. It is possible that women use greater pelvic motion in the coronal plane to reduce their vertical COM displacement and, thus, conserve energy during walking. An increase in pelvic obliquity motion may be advantageous from an energy standpoint, but it is also associated with increased lumbosacral motion, which may be maladaptive with respect to the etiology and progression of low back pain.