Measuring and modelling human response to foot-transmitted vibration exposure

Foot-transmitted vibration (FTV) occurs when a worker is exposed to vibration through the feet and can occur when operating vibrating equipment such as bolters, jumbo drills, or crushers, or standing to operate mobile equipment such as locomotives and forklifts. Exposure to FTV has been linked to the development of vibration-induced white feet, a vascular disorder with reduced circulation to the toes causing blanching. Vibration research has been focused on whole-body vibration (WBV) and hand-arm vibration, with FTV being lumped in to standing WBV. This research includes, but is not limited to, resonant frequency identification, development of international standards governing safe exposure limits, personal protective equipment design, and model development. It is the intention of this research to initiate research specifically for FTV. The first step to preventing harmful exposure is to identify the resonant frequencies at different anatomical locations on the foot (Objective 1). The resonance of 24 anatomical locations on the foot was identified for 21 participants, where the most notable differences in the average peak frequency occurred between the toes (range: 99-147Hz), midfoot (range: 51-84Hz), and ankle (range: 16-39Hz). As workers do not normally stand in a completely natural position, it was equally important to measure how altering the location of the centre of pressure (COP) changes resonance and the transmissibility of vibration through the foot (Objective 2). The resonance at the same 24 anatomical locations was identified when the COP was pushed forward (towards toes) and backward (towards heels). Generally, resonance at the measurement location increased when the COP was concentrated to a particular portion of the foot. The third objective of this research was to reduce the measurements at 24 anatomical locations, from the first two objectives, down to a representative subset (Objective 3). Multiple correspondence analysis was conducted on the peak transmissibility magnitude in order to assess structure displacement leading to increases in potential injury risk. Transmissibility results were analysed based on two magnitude thresholds: at 2.0 indicating 100% amplification of the input signal, and at 2.5 indicating 150% amplification. Results indicate that transmissibility measurements at the nail bed of first phalange, head of first metatarsal, head of second metatarsal, and the lateral malleolus may be sufficient to effectively measure foot-transmitted vibration when participants changed their COP location from natural, forward and backward. Then a K-means analysis was conducted to minimize the anatomical locations necessary to capture the transmissibility response from 10 to 200 Hz, and using the reduced locations, a lumped-parameter model was designed and validated (Objective 4). Three locations (the nail of the big toe, the third metatarsal, and the lateral malleolus) were found to be sufficient for summarizing FTV transmissibility modulus. A three segment, four degrees-of-freedom lumpedparameter model of the foot-ankle system (FAS) was designed to model the transmissibility response at three locations when exposed to vertical vibration from 10 to 60 Hz. Reasonable results were found at the ankle, midfoot, and toes in the natural standing position and forward COP. However, when the COP is backward, the model does not sufficiently capture the transmissibility response at the ankle. Determining the resonant frequencies of the FAS is important for the prevention of vibration-induced injury. Resonance needs to be incorporated into the design of equipment, tools (e.g. anti-vibration drills, isolated platforms), and personal protective equipment (e.g. antivibration insoles or boots) can be modified to reduce vibration at the frequencies where tissue resonance occurs. These findings could also inform the development of new international standards for measuring/reducing exposure to FTV.Doctor of Philosophy (PhD) in Natural Resources Engineerin

Effect of the Shoe Sole on the Vibration Transmitted from the Supporting Surface to the Feet

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

The 3 C’s of Consideration for COVID-19 Workplace Fever Detection Device Selection: Context, Calibration & Cost

COVID-19 screening protocols have become normal practice for employees entering workplaces around the world. However, workplace screening programs that include temperature detection via infrared thermometers or thermal detection cameras often violate many technical specifications for the correct use of these devices. Therefore, this article aims to provide practical guidance for non-thermal imaging specialists responsible for selecting thermal detection devices for workplace screening protocols. Focusing on three critical points of consideration, including the context of use, calibration of equipment, and cost of purchase and maintenance, readers are presented with a framework to guide their decision-making. This framework not only prioritizes the health and wellbeing of employees by ensuring the context of use is appropriate but balances the cost of calibration, purchasing and additional supporting supplies. Further, the presented framework extends beyond the COVID-19 pandemic and can be easily adapted to implement any new workplace technology

Comparison Between the Biomechanical Responses of the Hand and Foot When Exposed to Vertical Vibration

Workers can be exposed daily to foot-transmitted vibration (FTV) from standing on mobile equipment or vibrating platforms and surfaces. This results in a consistent risk of developing neurological, vascular, and musculoskeletal problems. To date, there are no international stand-ards describing procedures with which to evaluate the health risks deriving from long-term ex-posure to FTV. To study the applicability of hand–arm vibration (HAV) standards to the foot, the biomechanical responses of the hand and foot in terms of the frequency response function upon varying contact conditions were compared. Results evidenced similarities between the responses of the wrist and ankle, with differences in resonance for the fingers and toes. The study confirms that HAV standards are more suitable than whole-body vibration standards for evaluating higher frequency exposure to FTV

Four degree-of-freedom lumped parameter model of the foot-ankle system exposed to vertical vibration from 10 to 60 Hz with varying centre of pressure conditions

Modelling the foot-ankle system (FAS) while exposed to foot-transmitted vibration (FTV) is essential for designing inhibition methods to prevent the effects of vibration-induced white-foot. K-means analysis was conducted on a data set containing vibration transmissibility from the floor to 24 anatomical locations on the right foot of 21 participants. The K-means analysis found three locations to be sufficient for summarising the FTV response. A three segment, four degrees-of-freedom lumped parameter model of the FAS was designed to model the transmissibility response at three locations when exposed to vertical vibration from 10 to 60 Hz. Reasonable results were found at the ankle, midfoot, and toes in the natural standing position (mean-squared error (ε) = 0.471, 0.089, 0.047) and forward centre of pressure (COP) (ε = 0.539, 0.058, 0.057). However, when the COP is backward, the model does not sufficiently capture the transmissibility response at the ankle (ε = 1.09, 0.219, 0.039).This work was supported by a Natural Science and Engineering Council of Canada Discovery Grant [RGPIN/ 4252-2015]

Acupuncture for pain and osteoarthritis of the knee: a pilot study for an open parallel-arm randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>There is some evidence that acupuncture for pain and osteoarthritis (OA) of the knee is more than a placebo, and short term clinical benefits have been observed when acupuncture is compared to usual care. However there is insufficient evidence on whether clinical benefits of acupuncture are sustained over the longer term. In this study our key objectives are to inform the design parameters for a fully powered pragmatic randomised controlled trial. These objectives include establishing potential recruitment rates, appropriate validated outcome measures, attendance levels for acupuncture treatment, loss to follow up and the sample size for a full scale trial.</p> <p>Methods</p> <p>Potential participants aged over 50 with pain and osteoarthritis of the knee were identified from a GP database. Eligible patients were randomised to either 'acupuncture plus usual care' and 'usual care' alone, with allocation appropriately concealed. Acupuncture consisted of up to 10 sessions usually weekly. Outcome measures included Western Ontario and McMaster Universities (WOMAC) index with the sample size for a full scale trial determined from the variance.</p> <p>Results</p> <p>From the GP database of 15,927 patients, 335 potential trial participants were identified and invited to participate. After screening responses, 78 (23%) were identified as eligible and 30 patients who responded most promptly were randomised to 'acupuncture plus usual care' (15 patients) and 'usual care' alone (15 patients). Attendance for acupuncture appointments was high at 90% of the maximum. Although the trial was not powered to detect significant changes in outcome, the WOMAC pain index showed a statistically significant reduction at 3 months in the acupuncture group compared to usual care. This was not sustained at 12 months. The sample size for a fully powered two-arm trial was estimated to be 350.</p> <p>Conclusion</p> <p>This pilot study provided the evidence that a fully powered study to explore the longer term impact of acupuncture would be worthwhile, and relevant design features for such a trial were determined.</p> <p>Trial registration number</p> <p>ISRCTN25134802.</p

Foot-transmitted vibration: exposure characteristics and the biodynamic response of the foot

Research shows miners can be exposed to foot-transmitted vibration (FTV) when operating various pieces of underground mining equipment, and case reports suggest workers are experiencing symptoms similar to those of hand-arm vibration syndrome in their feet. A field study was conducted to measure and document FTV exposure associated with operating underground mining equipment, and probable health risks were determined based on both ISO 2631-1 (1997) for WBV and ISO 5349-1 (2004) for HAV. Seventeen participating operator’s also reported musculoskeletal discomfort. Seventeen male participants ranging between 24-61 years of age, with an average height and mass of 175.0cm and 88.2kg volunteered for the study. Seventeen pieces of equipment were tested; 1 locomotive, 1 crusher, 9 bolter drills (4 scissor platforms, 2 Maclean, 2 Boart/basket, and 1 RDH), and 6 jumbo drills. Including all seventeen pieces of underground mining equipment, the vibration acceleration ranged from 0.13-1.35m/s2 with dominant frequencies between 1.25-250Hz according to ISO 2631-1. According to ISO 5349-1 vibration acceleration ranged from 0.14-3.61m/s2 with dominant frequencies between 6.3-250Hz. Furthermore, the magnitude of FTV measured on the jumbo drills with grated platforms (#5 and #6) was less than FTV measured from the jumbo drills with, solid metal surfaces. Additionally, twelve of the seventeen equipment operators indicated a complaint of discomfort in their lower body (specifically at the level of the knee or lower). The health risk analysis based on ISO 2631-1 indicated that one operator (bolter drill #9) was exposed to vibration above the criterion value, while the health risk analysis based on ISO 5349-1 indicated iv that two operators (jumbo drill #1 and bolter drill #1) were exposed to vibration above the criterion value. Operators reported very severe or severe discomfort; however, the same operators were not the operators of the equipment with FTV exposure levels above the ISO standards, leaving evidence to suggest that the standards are not properly assessing injury risk to vibration exposure via the feet. Future research is needed to develop a standard specific for FTV and to determine the link between early musculoskeletal injury reporting and the onset of vibration white foot. To do so, a better understanding of the biodynamic response of the foot to FTV is needed. A laboratory study was conducted to 1) measure and document transmissibility of FTV from (a) floor-to-ankle (lateral malleolus), and (b) floor-to-metatarsal, during exposure to six levels of vibration (25Hz, 30Hz, 35Hz, 40Hz, 45Hz, and 50Hz) while standing, and 2) to determine whether independent variables (vibration exposure frequency, mass, arch type) influence transmissibility (dependent variable) through the foot. A two-way repeated measures analysis of variance (ANOVA) was conducted. There was a significant interaction between transmissibility location and exposure frequency (λ = 0.246, F (5,25) = 15.365, p = 0.0001). There were significant differences in mean transmissibility between the ankle and metatarsal at 40Hz [t(29) = 4.116, p = 0.00029], 45Hz [t(29) = 6.599, p = 0.00000031], and 50Hz [t(29) = 8.828, p = 0.000000001]. The greatest transmissibility at the metatarsal occurred at 50Hz and at the ankle (lateral malleolus) transmissibility was highest from 25-30Hz, indicating the formation of a local resonance at each location. v Future research should focus on identifying resonance frequencies at different locations on the feet. This information is needed to develop an exposure guideline to help protect workers from exposure to FTV, and to develop personal protective equipment capable of attenuating harmful FTV exposure frequencies.Master of Human Kinetics (MHK

Inclusive user interfaces : a theory of design.

College of Science; Computer Science Department; Advisor: Mr. R. Kevin Preston; Date: April 21, 2020; Pages: 21 p.; This paper was submitted during the COVID-19 Pandemic of 2020. UAH went to remote learning in the middle of March 2020 to the end of the Spring Semester

The Effects of Altering the Center of Pressure in Standing Subjects Exposed to Foot-Transmitted Vibration on an Optimized Lumped-Parameter Model of the Foot

Many workers are exposed to foot-transmitted vibration, which can lead to the development of vibration-induced white foot: a debilitating condition with neurological, vascular and osteoarticular symptoms. To design effective prevention mechanisms (i.e., boots and insoles) for isolating workers from vibration exposure, continued model development of the foot’s biodynamic response in different positions is necessary. This study uses a previously developed model of the foot–ankle system (FAS) to investigates how altering the center of pressure (COP) location can change the biodynamic response of the FAS to standing vibration exposure. Formerly published experimental responses for apparent mass and transmissibility at five anatomical locations in three COP positions were used to optimize the model. Differences occurred with the Kelvin–Voigt elements used to represent the soft tissues of the foot sole: at the heel, the distal head of the metatarsals and distal phalanges. The stiffness increased wherever the COP was concentrated (i.e., forward over the toes or backward over the heel). The variability of the model parameters was always greatest when the COP was concentrated in the heel. This suggests future FAS models need to more clearly address how the soft tissue of the plantar fat pad is modelled

Standing centre of pressure alters the vibration transmissibility response of the foot

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 &lt; .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