Exposure to foot-transmitted vibration (FTV) can lead to pain and numbness in the toes and feet, increased cold sensitivity, blanching in the toes, and joint pain. Prolonged exposure can result in a clinical diagnosis of vibration-induced white foot (VIWFt). Data on the biomechanical response of the feet to FTV is limited; therefore, this study seeks to identify resonant frequencies for different anatomical locations on the human foot, while standing in a natural position. A laser Doppler vibrometer was used to measure vertical (z-axis) vibration on 21 participants at 24 anatomical locations on the right foot during exposure to a sine sweep from 10-200Hz with a peak vertical velocity of 30 mm/s. The most notable differences in the average peak frequency occur between the toes (range: 99-147Hz), midfoot (range: 51-84Hz), and ankle (range: 16-39Hz). The biomechanical response of the human foot exposed to foot-transmitted vibration, when standing in a natural position, was measured for 21 participants. The foot does not respond uniformly; the toes, midfoot, and ankle regions need to be considered independently in future development of isolation strategies and protective measures.

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. Exposure to foot-transmitted vibration (FTV) has been linked to injury; however, the biod

Adopting non-neutral sitting postures while exposed to whole-body vibration (WBV) can put heavy equipment operators at an increased risk for lower back pain and may cause damage to the spinal tissue. A laboratory experiment involving 11 participants (5 females, 6 males) completing four 45-min test sessions incorporating different seated conditions (vibration versus no vibration, and rotation versus no rotation) was used to assess seat-to-head transmissibility (STHT) and self-reported discomfort while in four rotated neck and trunk postures. The vibration exposure profile was a constant vertical sinusoidal signal with a frequency of 3 Hz and 0.7 m/s² acceleration. Vibration measured at the head was greater than at the seat under all conditions, with a statistically significant effect of time (F_1,10 = 101.73, p < 0.001, Eta² = 0.910) and posture (F_3,8 = 5.64, p = 0.023, Eta² = 0.679). Mean self-reported discomfort ratings revealed increased participant discomfort in rotated neck and trunk positions in both vibration and non-vibration conditions. Increasing time also had a significant (F(1,10) = 15.53, p = 0.003) impact on higher rates of participant discomfort. Overall, it was found that increasing the degree of rotated neck and trunk position from neutral amplified the STHT and self-reported discomfort.

Vibration white foot as an occupational disease has underscored the need to better understand the vibration response of the foot. While vibration transmissibility data exist for a natural standing position, it is anticipated that weight distribution will affect the response. The purpose of this study was to determine the effects of changes in centre of pressure (COP) on the foot’s biomechanical response. Twenty-one participants were exposed to vertical vibration of 30 mm/s, with a sine sweep from 10-200 Hz. Z-axis (vertical) vibration was measured at 24 locations on the right foot, with the COP shifted forward or toward the heel. A mixed model analysis at each location revealed significant differences (p<.001) in the transmissibility response when the COP was altered to the forefoot and rearfoot. In general, the peak frequency of the average vibration response increased for a region of the foot when the COP was shifted toward that region. Practitioner Summary: Altering the centre of pressure location resulted in changes in the transmission of vibration through the foot. The forward lean position was associated with the greatest amplitude of vibration transmissibility at the toes. This information is relevant for clinicians studying vibration-induced white-foot and engineers designing protective equipment.

Vibration transmitted through the foot can lead to vibration white feet, resulting in blanching of the toes and the disruption of blood circulation. Controlled studies identifying industrial boot characteristics effective at attenuating vibration exposure are lacking. This work focused on the evaluation of vibration transmissibility of boot midsole materials and insoles across the range 10–200 Hz at different foot locations. Questionnaires were used to evaluate the comfort of each material. The materials were less effective at attenuating vibration transmitted to the toe region of the foot than the heel. Between 10 and 20 Hz, all midsole materials reduced the average vibration transmitted to the foot. The average transmissibility at the toes above 100 Hz was larger than 1, evidencing that none of the tested material protects the worker from vibration-related risks. There was a poor correlation between the vibration transmissibility and the subjective evaluation of comfort. Future research is needed to identify materials effective for protecting both the toe and the heel regions of the foot. Specific standards for shoe testing are required as well.