Quantifying the Recovery Response and Role of Hand Strength During Ladder Falls

描述(申请人提供)：从梯子上坠落是导致职业伤害和死亡的主要原因之一。导致从梯子上摔下来的主要因素是失足和脚滑，这会导致脚与梯级脱钩，从而导致摔倒。在发生滑倒/失足后，一个人必须依靠与失足相反的手和脚来阻止他们跌倒，并在梯子上恢复平衡。这一反应必须迅速执行，需要上半身和下半身之间的协调。目前，关于一个人在攀岩过程中从滑倒和失误中恢复的能力，以及使用上肢或下肢实现这种恢复所需的生物力学反应，存在着一个关键的知识缺口。这项R21建议的总体目标是获得关于生物力学原因和梯子跌倒后恢复反应的定量知识，以及手部力量在梯子滑倒和失误恢复中的作用。理由是，成功完成这一目标将导致改进梯级设计和攀登实践，最大限度地提高康复的可能性，并最终减少梯子坠落受伤和死亡。具体目标#1是描述梯子失足和打滑的感觉运动过程。第一个目标是确定对于检测是否发生失误/滑倒最关键的感觉系统。第二个目标是确定对从干扰中恢复最负责的肌肉群。将描述上半身和下半身对滑倒和失误的协调反应。为了实现这一特定目标，受试者将在攀登梯子的过程中，分别通过让梯子的一个横档自动释放和一个横档自由旋转，同时记录可用的感觉输入和运动反应，从而使受试者同时接触到模拟的失足和打滑。感觉系统的输入将以脚部力量和压力中心为特征，用于足部体感，手部力量用于手部体感，关节角度用于本体感觉，头部加速度用于前庭感觉。对失足/滑倒的生物力学反应将通过记录反应过程中关节力矩、肌肉活动和上下半身所做的功来表征。将确定在扰动期间感觉运动反应与未受干扰的爬梯相比的偏差的起始和大小，以及肌肉活动的排序，以确定用于检测扰动和恢复的关键运动反应的关键感觉系统。具体目标#2是确定手的力量对一个人从梯子上摔下来的恢复能力的作用。这个假设是，受试者的手的力量与干扰结果(跌倒与恢复)显著相关。我们将比较不同手力水平的三组受试者的扰乱结果。如果低手力组比其他组更频繁地摔倒，这一假设将得到支持。这项研究代表着向长期目标又迈进了一步，即通过实施基于跌倒涉及的生物力学因素的人体工程学设计改变，防止在梯子上跌倒造成致命和致残伤害。 与公共卫生相关：因失足从梯子上坠落的事故造成了大量严重的职业伤害和死亡。了解身体对梯子上滑倒和失误的反应，以及手的力量所起的作用，对于设计梯子和减少失误后摔倒的可能性的攀登练习至关重要。这个项目将测量和描述对梯子失误的反应过程，并确定手的力量对恢复过程的贡献。

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.