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

描述（由申请人提供）：从梯子上摔下来是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倒，这导致脚与梯级分离，从而导致坠落。在发生滑倒/失足后，一个人必须依靠他们的手和失足对面的脚来阻止他们跌倒并在梯子上恢复平衡。这种反应必须迅速进行，需要上半身和下半身的协调。目前，人们在攀登过程中从滑倒和失足中恢复的能力，以及使用上肢或下肢实现这种恢复所需的生物力学反应，在知识方面存在关键空白。本R21提案的总体目标是获得关于梯子跌落的生物力学原因和恢复反应的定量知识，以及手力量在梯子滑倒和失足恢复中的作用。其基本原理是，成功完成这一目标将改进梯子的设计和攀登练习，从而最大限度地提高恢复的可能性，并最终减少梯子坠落造成的伤害和死亡。具体目标1是将感觉运动过程描述为阶梯失足和滑倒。第一个目标是确定对检测失误/滑倒发生最关键的感觉系统。第二个目标是确定最负责从扰动中恢复的肌肉群。协调上半身和下半身对滑倒和失误的反应将被表征。为了实现这一特定目标，受试者将分别在梯子的一个横档自动释放和一个横档自由旋转的情况下，在爬梯过程中模拟失足和滑倒，同时记录可用的感觉输入和运动反应。感觉系统输入的特征包括足部体感的足力和压力中心，手体感的手力，本体感觉的关节角度，前庭感觉的头部加速度。失误/滑走的生物力学反应将通过记录关节力矩、肌肉活动和上半身和下半身在反应过程中所做的工作来表征。与未受干扰的梯子攀登相比，在扰动期间感觉运动反应的开始和偏差的大小以及肌肉活动的顺序将被确定，以确定检测扰动的关键感觉系统和恢复的关键运动反应。具体目标2是确定手的力量对一个人从梯子跌落中恢复的能力的作用。假设是，受试者的手部力量与扰动结果（跌倒与恢复）显著相关。扰动结果率将在三个具有不同手强度水平的受试者组中进行比较。如果低手力量组比其他组摔倒更频繁，该假设将得到支持。这项研究表明，通过实施基于跌倒所涉及的生物力学因素的人体工程学设计变化，我们离防止梯子跌落造成的致命和致残伤害的长期目标又近了一步。

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.