LIMB COLLAPSE AND FALLS AMONG ELDERLY

保护性步进是用于平衡恢复的常见响应。然而，保护性踏步失败的潜在机制在很大程度上是未探索和未知的。我们正在开创一条工作路线，专注于保护性步骤失败的确切原因。我们希望我们的研究为未来的干预措施铺平道路，在物理康复的特异性原则的基础上。我们将首先证明，肢体塌陷是失败的主要原因，在保护步骤，年龄和性别是成功的尝试，以恢复平衡后肢体塌陷的关键决定因素。 我们将检验以下假设：所有受试者在日常活动中意外滑倒时都会发生肢体塌陷，并且与年轻人（22-45岁）和男性相比，更多的老年人（65-80岁）和女性无法从肢体塌陷中恢复。为了理解为什么一些老年受试者能够从肢体塌陷中恢复，而另一些则不能，我们接下来将确定肢体塌陷的生物力学原因。我们将测试的假设，肢体塌陷是不可避免的，在一些研究生科目，因为支撑膝关节（而不是髋关节或踝关节）未能产生扭矩达到阈值的恢复，而且这个阈值是可预测的。为了找到加强个体对肢体塌陷的抵抗力的具体方法，我们将研究从肢体塌陷中恢复的神经肌肉机制。我们将检验以下假设：伸展力矩不足是由长时间的、反射性介导的抑制引起的，类似于惊吓或其他相关反应的某些组成部分，而不是由在质心垂直下降的关键时间窗口期间前馈编程失败引起的。我们的长期目标是发展康复计划，以促进和加强老年人自己的抵抗力，以灾难性的福尔斯下降，由于肢体崩溃。 其结果将是减少医疗保健费用和不必要的伤害，目前降低了灾难性福尔斯受害者的流动性和生活质量。

Protective stepping is a common response used for balance recovery. Nevertheless, the mechanisms underlying situations where protective stepping fails are largely unexplored and unknown. We are pioneering a line of work that focuses on the precise causes for failure in protective stepping. We expect our research to pave the way for future interventions based on the specificity principle in physical rehabilitation. We will first demonstrate that limb collapse is the major cause for failure in protective stepping, and that age and gender are critical determinants in successful attempts to regain balance after limb collapse. We will test the hypotheses that limb collapse will occur in all subjects during unexpected slipping in the execution of a daily activity, and that a greater number of older adults (ages 65-80 years) and female adults will not be able to recover from limb collapse than young adults (ages 22-45 years) and male adults. In order to understand why some older subjects are able to recover from limb collapse while other fail to do so, we will next determine the biomechanical causes for limb collapse. We will test the hypotheses that limb collapse is inevitable in some graduate subjects because the supporting knee (instead of hip or ankle) has failed to generate torques to reach threshold value for recovery, and furthermore that this threshold is predictable. In order to find the specific means to strengthen an individual's resistance to limb collapse, we will then examine the neuromuscular mechanisms for recovery from limb collapse. We will test the hypotheses that insufficient extension torques result from a prolonged, reflexively mediated inhibition similar to some component of startle or other related responses, rather than from a failure of feed-forward programming during the critical time-window of center of mass vertical descent. Our long-term goal is to develop rehabilitation programs that will facilitate and fortify elderly individuals' own resistance to catastrophic falls due to limb collapse. The results will be a reduction in both costs of health care and in unnecessary injury that currently lowers the mobility and the quality of life of victims of catastrophic falls.