Functional effects of active muscle stiffness on movement in the elderly

老年时，人们通常难以进行日常活动，比如从椅子上站起来。这种下降的原因尚不完全清楚。虽然人们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，老年人在支撑身体对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，使他们在某种程度上僵硬，阻碍了全身运动。然而，对肌肉僵硬的影响缺乏基本的认识，这主要是由于在运动过程中测量僵硬的技术困难。我们提出的项目将开发和测试一种新的方法来测量人们从椅子上站起来时的肌肉僵硬度，这对老年人来说是一种挑战。我们会制造一种稍微推人的设备吗？S腿，并测量存在多少阻力。这将使我们能够确定他们身体的哪个部位以及在运动时他们是僵硬的。我们也会推人吗？当他们安静地坐着的时候。这将帮助我们了解人们支撑自己对抗重力的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装置，我们将进行实验，看看老年人是否确实比年轻人更僵硬，在某种程度上，当他们坐着和站起来时，这是有害的。我们还将检查身体僵硬的人是否比身体不那么僵硬的人更难以从椅子上站起来。如果他们这样做了，这就意味着教会那些行动困难的老年人在行动时减少紧张是很重要的。如果我们的假设是正确的，未来的研究将使用我们的协议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.