GENDER DIFFERENCES IN THE BALANCE OF HEALTHY ELDERLY AS DEMONSTRATED BY DYNAMIC POSTUROGRAPHY

Background. Prior studies indicate that older women fall more often th an men although there is no evidence of gender-based balance differenc es. Using a force platform, we measured the effects of restricted sens ory input and support surface movement to detect gender differences in balance. Methods. Healthy, elderly community dwellers (N = 234, mean age = 76 +/- 5 years, 52% female) were administered the following pert urbations on the balance platform: The platform and/or visual surround were fixed or tilted proportionally to the subject's sway with the ey es open or closed, forward or backward horizontal translations, and to es-up and toes-down rotations. Results. Gender-based balance differenc es were not present during quiet standing, or when the support surface or visual input were manipulated separately. Women swayed and lost th eir balance more than men when the surface was sway-referenced while v ision was compromised, but by the third trial their sway control was c omparable to the men. Women also initially lost their balance more fre quently than men during toes-up and -down rotations, and compared to m en continued to lose their balance more often during repeated toes-up rotations. Finally, women developed less angular momentum than men in response to forward platform rotations. Discussion. Elderly women show impairments of balance when simultaneously deprived of visual and som atosensory inputs or during a backwards destabilization. Since there i s little evidence for a CNS source for such gender differences, biomec hanical origins (e.g., dorsiflexion strength and range of motion) are a more likely cause. Limited postural control of women under condition s stressing balance may explain their greater frequency of falling.