Kurt E. Beschorner, Ph.D. - US grants

DESCRIPTION (provided by applicant): Falls from ladders represent one of the leading causes of occupational injuries and fatalities. The primary factors contributing to falls from ladders are missteps and foot slips, which cause foot de-coupling from the rung leading to a fall. After a slip/misstep occurs, a person must rely on their hands as well as the foot opposite to the misstep to stop their fall and regain balance on the ladder. This response must be executed rapidly and requires coordination between the upper and lower body. Currently, there is a key gap in knowledge related to the ability of a person to recover from slips and missteps during climbing and the biomechanical response necessary to achieve this recovery using the upper or lower limbs. The overall objective of this R21 proposal is to gain quantitative knowledge on biomechanical causes and recovery response from a ladder fall as well as the role of hand strength in recovering from a ladder slip and misstep. The rationale is that successful completion of this objective will lead to improved ladder rung design and climbing practices that maximize the likelihood of a recovery and ultimately reduce ladder fall injuries and fatalities. Specific aim #1 is to characterize the sensorimotor process to a ladder misstep and slip. The first objective is to identify the sensory system that is most critical for detecting that a misstep/slip has occurred. The second objective is to identify the muscle groups that are most responsible for recovery from the perturbation. The coordinated upper- and lower- body response to slips and missteps will be characterized. To accomplish this specific aim, subjects will be exposed to both a simulated misstep and slip during ascent of a ladder by having a rung of the ladder automatically release and a rung freely spin, respectively, while available sensory input and motor response are recorded. Sensory system input will be characterized by foot forces and center of pressure for foot somatosensation, hand forces for hand somatosensation, joint angles for proprioception, and head acceleration for vestibular sensation. The biomechanical response to the misstep/slip will be characterized by recording the joint moments, muscle activity and work performed in the upper and lower body during the response. Onset and magnitude of deviations of the sensorimotor response during perturbation compared to unperturbed ladder climbing as well as the sequencing of muscle activity will be determined to identify the critical sensory system for detecting a perturbation and critical motor response fo recovery. Specific aim #2 is to determine the role of hand strength on a person's ability to recover from ladder fall. The hypothesis is that subjects' hand strength is significantly associate with the perturbation outcome (fall vs. recovery). The perturbation outcome rate will be compared across three subject groups with different levels of hand strength. The hypothesis will be supported if the low hand strength group falls more frequently than other groups. This research represents a step closer to the long-term goal to prevent fatal and disabling injuries from falls on ladders by implementing ergonomic design changes based upon biomechanical factors involved in falls. PUBLIC HEALTH RELEVANCE: Fall accidents from ladders caused by a misstep account for a large number of serious occupational injuries and fatalities. Understanding the response of the body to slips and missteps on a ladder and the role of hand strength is critical to designing ladders and climbing practices that reduce the likelihood of a fall after a misstep. This project will measure and characterize the response process to ladder missteps and determine the contribution of hand strength to the recovery process.

? DESCRIPTION (provided by applicant): 1 Slip and fall accidents are a major and growing source of occupational injuries. Shoes that are heavily worn 2 have reduced coefficient of friction (COF) and are associated with increased slipping risk. The mechanism 3 causing this loss of friction is that worn tread can no longer channel fluids from beneath the shoe, which causes 4 the fluid to become pressurized, the COF to decrease and the slip risk to increase. Key knowledge gaps exist 5 regarding the factors that contribute to shoe wear rate and the wear thresholds at which COF begins to 6 decrease. This gap inhibits selection of wear-resistant shoes and programs that replace shoes before they 7 become too worn. The overall objective of this R01 study is to fill this gap by identifying the underlying 8 causes to shoe wear and identifying the tread thresholds where shoes become unsafe. The proposed research 9 will accomplish this goal with: 1) experiments that identify the factors that contribute to wear rate (Aim 1) and 10 replacement thresholds for worn shoes (Aim 2); 2) a computational model that predicts wear rate and the life 11 expectancy of shoes (Aim 3); 3) a validation of Aims 1 and 3 based on tracking wear in occupational settings 12 (Aim 4); and 4) a validation of Aim 2 based on unexpected slips of participants donning naturally worn shoes 13 (Aim 5). To accomplish Aims 1 and 2, a shoe wear tester will reproduce the kinetics of stepping repeatedly to 14 accelerate the wear of the shoe tread. For Aim 1, the effects of shoe material and tread design on tread wear 15 rate will be quantified. For Aim 2, the impact of wear on COF and under-shoe fluid pressures will be 16 determined and tread thresholds where fluid pressures start to significantly increase will be identified. The 17 impact of fluid pressures on COF will be tested. For Aim 3, an iterative FEA model will be developed that 18 calculates wear based on the contact pressures and then updates the shoe geometry based on the calculated 19 wear. For Aim 4, two cohorts of twenty participants (one from Nabors Industries and one cohort from general 20 industry) will wear two different shoe designs. Shoe wear and number of steps will be tracked to validate the 21 degree to which the wear rates observed in the experiments (Aim 1) and the model (Aim 3) reflect actual wear 22 experienced in industry. For Aim 5, sixty individuals will be unexpectedly slipped while wearing naturally 23 worn shoes. This aim will validate the effect of shoes worn beyond their replacement limits (determined in Aim 24 2) on slip risk. This proposal will meet NIOSH's Research to Practice (R2P) initiative by identifying the 25 factors that affect the life of shoes and their replacement limits, which will be translated to practice through 26 industry partners, publications and training programs. The outputs of this research will be new knowledge on 27 when worn shoes should be replaced, what factors influence wear, and a computational model of shoe wear. 28 The outcomes will be improved shoe design and replacement policies that lead to a reduction in slip and fall 29 accidents from worn shoes. This research will address NORA Strategic Goals for Manufacturing (Goal 2), 30 Wholesale and Retail Trade (Goal 2) and Oil and Gas Extraction (Goal 4.2).

Project Summary Falls from ladders cause severe injuries and fatalities among workers. Despite well-established epidemiology that identifies slips and falls from ladders as an important problem, little is known regarding how ladder design or an individual's body affects slip and fall risk. Furthermore, no tests exist to assess the friction performance of ladder rungs. This knowledge gap is a major barrier in designing safer ladders and verifying their efficacy. The objective of this NIOSH R01 research study is to develop new methods for assessing friction performance of ladder rungs, friction requirements of ladder climbing, and their relationship with the occurrence of slipping during ladder climbing. The long-term goal of our research is to develop a set of ladder safety guidelines (ladder design guidelines and safe climbing guidelines) that can lead to a substantive reduction in the number of severe injuries and fatalities caused by ladder slip-and-fall events. This research is a continuation of an existing line of research (originally funded by a NIOSH R21 grant) where we have developed novel methods of measuring human subject responses to perturbations during ladder climbing. The preliminary research by the team has led to five published peer-review papers (and a sixth in review) as well as 15 conference abstracts/proceedings. The study consists of four aims. Aim 1: Quantify the impact of ladder design on required coefficient of friction (RCOF). Based on preliminary data, we hypothesize that friction requirements will be influenced by the angle of the ladder (H1.1) and the rung design (shape: H1.2; size: H1.3). Aim 2: Quantify the impact of the individual factors, height, obesity, and sex, on RCOF. We hypothesize that height (H2.1) will be negatively correlated with friction requirements. Furthermore, we hypothesize that differences will exist across obesity groups (H2.2) and sexes (H2.3). Aim 3: Quantify the impact of ladder design on traction performance, measured by the available coefficient of friction (ACOF). We hypothesize that rungs designated as ?non-slip? will perform better than those without this designation (H3.1); and that size (H3.2), orientation (H3.3) and shape (H3.4) will influence friction performance. Aim 4: Identify the ACOF measurement methods that best predict slipping. We hypothesize that slipping can be predicted with available friction and friction requirements (H4.1) and that different testing methods will vary in their ability to predict slipping (H4.2). This research project is expected to lead to specific ladder design interventions for safer ladders such as recommendations for ladder angle, rung size, and rung shape. Furthermore, this project is expected to lead to new validated testing methods that can be utilized in industry to discriminate between high and low traction rung designs to enable future innovations in ladder safety design. This research addresses several of NIOSH's Program Grid Intermediate Goals that mention falls from different levels or falls from ladders: 6.2(A) (Construction), 6.13 (B) (Services), 6.16 (B) (Wholesale/Retail), 6.18 (A) (Mining).