Author(s): MATSUSHITA, K., NAKAYAMA, T.2, ISHIGURO, K.2, SAITO, H.2, ENDO, N.2, SUZUKI, N.2, SYAKU, F.1, Institution: NIHON UNIVERSITY, Country: JAPAN, Abstract-ID: 1287

INTRODUCTION:
Many women wear high heels for fashion or occupational reasons. However, studies have reported that wearing high heels can alter the posture of the lower limbs and pelvis, leading to the occurrence of lower back pain. Among these, there is a variety of debates regarding the effects on the lumbar spine, with reports suggesting that wearing high heels can both increase and decrease lumbar lordosis, resulting in a lack of consensus. Therefore, this study aimed to estimate the posture of the lower limbs and lumbar spine in static standing posture while wearing high heels using VICON and OpenSim, and to examine their effects.
METHODS:
Static standing posture was captured using a three-dimensional motion analysis system when participants were barefoot and wearing four different heights of high heels. Four healthy female participants aged 20.75 (SD±0.43) years, weighing 51.25 (SD±9.03) kg, and with a height of 156.7 (SD±6.9) cm took part in the study. Heel heights of 1.5 cm, 3.0 cm, 6.0 cm, and 9.0 cm were used, and measurements were taken using VICON and four floor force plates (manufactured by AMTI). A marker set based on Plug-in Gait consisting of 39 markers was used, with an additional 34 markers attached to the thoracic and lumbar vertebrae for posture evaluation. Participants held a static standing posture for three seconds, with one second analyzed as the evaluation period. After static standing posture recording, missing markers were corrected using VICON, then adapted to the OpenSim model (FeMaleFullBodyModel_v2.0_OS4.osim) developed by Bruno et al., and Inverse Kinematics and Residual Reduction Algorithm were executed to calculate the angles of the lower limbs and lumbar spine.
RESULTS:
As heel height increased, there was a tendency for ankle plantarflexion angle to increase. Similarly, knee flexion angle tended to increase with higher heel heights, while hip angle showed minimal changes regardless of heel height. Pelvic posterior tilt angle showed an increasing trend with higher heel heights. However, lumbar lordosis angle showed minimal variation regardless of heel height.
CONCLUSION:
Wearing high heels forces ankle plantarflexion, leading to a kinematic chain of knee flexion and pelvic posterior tilt. Considering the minimal change in lumbar lordosis angle and the increased pelvic posterior tilt angle, it is suggested that the stability of unstable postures like high heels is controlled by the pelvis rather than the lumbar spine. Due to the limited number of participants in this study, further experiments and validation are necessary in the future.