Head stabilization in children of both genders during level walking.

Young healthy adults adopt a "head stabilization in space" strategy during walking by attenuating the acceleration going up from pelvis-to-head level. A gender difference exists in this control strategy, particularly evident in the control of medio-lateral dynamic equilibrium. This study aims at assessing whether this difference is already present at pre-pubertal age. Two groups of children (15 females and 15 males, age range: 8-11 years) were involved in the study. They were asked to walk at self-selected speed and movement data were collected using three inertial sensors firmly attached at pelvis (P), shoulder (S), and head (H) levels. The RMS of the accelerations of P, S, and H were computed along the antero-posterior (AP), medio-lateral (ML), and vertical (V) directions and used to compare the two groups. No differences were found between the two groups in the pelvis and shoulder acceleration RMS values. Conversely, lower head acceleration RMS values were found for the females in both the AP and ML directions. Both groups managed to attenuate the upper body AP and ML accelerations going from pelvis-to-head level, with higher attenuations found for the females. The results of this study suggest that the gender differences in the ability to control the head accelerations during gait, found in a previous study, are due neither to different mass distribution nor to a compensation of the greater pelvic motions, nor are they the result of gender related walking habits (e.g. use of high heels).