Study of the biodynamic response of the foot to vibration exposure

Abstract

BACKGROUND: Exposure to foot-transmitted vibration (FTV) has been linked to injury; however, the biodynamic response of the foot to FTV has not been quantified. OBJECTIVE: The objective was to measure vibration transmissibility from the floor-to-ankle, and the floor-to-metatarsal, during exposure to FTV while standing, and to determine if FTV exposure frequency, or participant mass or arch index (AI) influence the transmission of FTV through the foot. METHODS: Participants’ AI was measured. Four ADXL326, tri-axial accelerometers were utilized to measure vibration on the platform medial to distal head of first metatarsal, on the distal head of first metatarsal, on the platform paralleling the medial malleolus, and on the lateral malleolus. Participants were randomly exposed to FTV at 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz for 45 seconds. RESULTS: Neither the three-way interaction of location*frequency*AI [λ = 0.816, F(5,24) = 1.080, p = 0.396] or location*frequency*mass [λ = 0.959, F(5,24) = 0.203, p = 0.958] were significant ( p< 0.05). The location*frequency interaction was significant [λ = 0.246, F(5,25) = 15.365, p = 0.0001]. Differences in mean transmissibility between the ankle and metatarsal were significant at 40 Hz, 45 Hz, and 50 Hz ( p< 0.001). CONCLUSIONS: The greatest transmissibility magnitude measured at the metatarsal and ankle occurred at 50 Hz and 25– 30 Hz respectively, suggesting the formation of a local resonance at each location.