title: Apparent mass distribution at the feet of standing subjects exposed to whole-body vibration.
abstract: This study was carried out to investigate the influence of the body posture and of the foot support on the apparent mass distribution at the feet of standing subjects exposed to whole-body vibration. The apparent mass was measured at the driving point through a capacitive pressure sensor matrix, which allowed to separate the contributions of the different foot regions. The overall value was also determined using a conventional measurement system based on piezoelectric load cells. Ten male subjects performed 15 tests with three kinds of feet supports (flat rigid, anatomic rigid and flat soft) in five different postures. Static components of the pressure measurements were exploited to identify which fraction of the weight is supported by the rearfoot, the midfoot and the forefoot in the various test configurations. Factorial design of experiments on different response variables showed that the apparent mass is affected by the posture but not by the type of feet contact surface; conversely, the presence of insoles varies with the apparent mass distribution on the different feet parts.
  The response of standing subjects to whole-body vibration has always been considered as a global parameter measured at the driving point, neglecting the local phenomena occurring in different foot parts. We have experimentally identified the apparent mass distribution of subjects in different standing postures and with different foot supports.
authors.affiliation: Department of Mechanics, Politecnico di Milano, Via M. d'Oggiono 18/a , 23900, Lecco, Italy. marco.tarabini@polimi.it
authors.forename: Marco
authors.initials: M
authors.lastname: Tarabini
authors.forename: Bortolino
authors.initials: B
authors.lastname: Saggin
authors.forename: Diego
authors.initials: D
authors.lastname: Scaccabarozzi
authors.forename: Davide
authors.initials: D
authors.lastname: Gaviraghi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Moschioni
mesh_terms: D000328:Adult; D005528:Foot / Q000502:physiology*; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D011312:Pressure; D014732:Vibration; D016474:Weight-Bearing