Functional effects of active muscle stiffness on movement in the elderly

到了老年，人们通常很难做出日常动作，比如从椅子上站起来。这一下降的原因尚不完全清楚。尽管人们会随着年龄的增长而失去力量，但这并不能完全解释他们的问题。研究表明，老年人在支撑身体抵抗重力和开始运动时，肌肉会紧张。我们认为，这代表了一种主要缺陷，使它们在某种程度上更加僵硬，阻碍了全身运动。然而，人们对肌肉僵硬的影响基本缺乏了解，这主要是由于在运动中测量僵硬的技术困难。我们提议的项目将开发和测试一种新的方法，当人们从椅子上站立时，测量肌肉硬度，这对老年人来说是具有挑战性的。我们将建造一种设备，轻微地挤压人的S的腿，并测量存在多大阻力。这将使我们能够确定它们在身体的哪个部位以及在运动中何时僵硬。我们还会在人们安静地坐着的时候推S的腿。这将帮助我们了解人们对抗重力的支撑方式是否会导致他们的肌肉僵硬。一旦我们制造并测试了这个设备，我们将进行实验，看看老年人坐着和站起来时是否真的比年轻人僵硬，这是有害的。我们还将研究僵硬的人是否比僵硬的人更难从椅子上站起来。如果他们这样做了，这意味着教育行动困难的老年人在行动时使用较少的紧张将是重要的。如果我们的假设是真的，未来的研究将使用我们的方案来检查和验证可能的再培训方法。

In old age, people commonly have difficulty making everyday movements, such as standing up from a chair. The reason for this decline is not fully understood. Although people lose strength as they age, this does not fully explain their problem. Research has shown that older adults tense muscles as they support their body against gravity and as they start to move. We suggest this represents a primary deficit that makes them stiffer in a way that hampers whole-body movement. However, there is a basic lack of knowledge about the effects of muscle stiffness that is primarily due to technical difficulties in measuring stiffness during movement. Our proposed project will develop and test a new method for measuring muscle stiffness as people stand up from a chair, which elderly people find challenging. We will build a device that slightly pushes on people?s legs, and measures how much resistance there is present. This will enable us to determine where in their body and when in the movement they are stiff. We will also push on people?s legs while they are sitting quietly. This will help us understand whether the way people support themselves against gravity causes their muscles to be stiff. Once we have built and tested this device, we will perform experiments to see whether older people are indeed stiffer than young people, in a way that is detrimental, when they sit and stand up. We will also examine whether stiff people have more difficulty standing up from a chair than people who are less stiff. If they do, this would mean that it will be important to teach older adults who have difficulties moving to use less tension as they move. If our hypothesis is true, future studies will use our protocol to examine and validate possible retraining methods.