The transmission of vertical whole-body vibration to the body segments of standing subjects

The effects of body postures in standing position on the transmission of whole-body vibration to body segments have been investigated. The magnitude acceleration in the 2-axis direction of six body segments: the metatarsus, ankle, knee, hip, shoulder and head has been measured during exposure to random vibration. Ten male subjects exposed to floor vibration stood in ten postures described as: relaxed standing, legs stiffened, legs bent, standing on the toes, standing on one leg with or without support of the other foot and standing in steps. The transmissibility of random vibration from the floor to the body points was calculated at frequencies ranging from 4-250 Hz in 1/3 octave bands. The body postures of the subjects modified both the width of the resonant bands and the transmissibility values. The squared multiple correlation coefficient (R-2) between the transmissibility and the 16 variables (10 postures, 6 body segments) was not very high at resonance frequencies in the range 4-12.5 Hz but above 25 Hz, 50% of the variability in the transmissibility was due to the postures and the body segments. (C) 1998 Academic Press.