First steps: the mechanics and control of velocity change in humans

人类用两条腿走来走去似乎大部分时间都是毫不费力的。然而，特别是随着我们年龄的增长，不幸的是，跌倒造成的伤害非常常见。为了了解如何减少跌倒的频率，并帮助防止我们的肌肉、关节、骨骼、肌腱和韧带受到其他伤害，我们需要提高对运动系统如何工作的理解。运动研究主要集中在所谓的稳态活动上，比如站在一个地方，或者在跑步机上以恒定的速度移动。然而，许多伤病发生在其他时间，如启动、停止或转弯时。这些都是本研究项目的重点活动。问题是，研究这些运动形式非常困难，因为就其本质而言，它们不会简单地以一种容易控制的方式重复自己。因此，我们计划研究人们在实验室里自由走动以及对口头指令(如“左转”、“停车”)的反应。当他们这样做的时候，我们将记录他们的身体发生了什么，就是做工作的肌肉，肢体执行的动作，以及施加到外部世界的力。然而，这只告诉了我们故事的一半。我们真的很想知道发生了什么，在这个水平上，我们可以利用这些信息来开发我们可以用于康复或训练的技术。这意味着我们需要知道体内发生了什么。这在实验上是非常困难的，所以我们提议构建复杂的计算机运动模型，可以使用超级计算机来训练，以模仿我们从实验对象那里记录的动作。在计算机模型中，我们可以调查和控制正在发生的一切，这让我们可以更全面地了解情况。在计算机中，我们可以模拟肌肉力量的变化，以模拟与衰老相关的变化，测量其影响，并直接测试有助于改善运动能力的策略和治疗方法。这种“在电子计算机中”的方法填补了纯实验方法留下的空白，并使我们能够出于实际和纯粹的理论原因对运动有更完整的理解。

Humans moving around on two legs appear to do this effortlessly most of the time. However, particularly as we get older, injuries due to falls are unfortunately very common. In order to understand how to reduce the frequency of falls, and to help prevent other injuries to our muscles, joints, bones, tendons and ligaments, we need to improve our understanding of how the locomotor system works. Locomotor research has concentrated primarily on what are called steady state activities such as standing in one place, or moving at a constant speed on a treadmill. However a lot of injuries occur at other times such as when starting, stopping or turning. These are the activities that are the focus of this research project. The trouble is that it is very hard to study these forms of locomotion because, by their very nature, they do not simply repeat themselves in an easily controlled fashion. We therefore plan to study people moving freely around the laboratory and responding to spoken commands (e.g. "turn left", "stop"). While they are doing this we will record what happens to their bodies in terms of the muscles that are doing the work, the movements that the limbs perform, and the forces that are applied to the outside world. However this only tells us half the story. We really want to know what is going on at a level where we can use the information to develop techniques that we can use in rehabilitation or training. That means that we need to know what is going on inside the body. This is very difficult to do experimentally so we are proposing instead to construct sophisticated computer models of locomotion that can be trained, using a supercomputer, to mimic the actions that we record from experimental subjects. In the computer model we can inestigate and control everything that is happening which lets us get a much more complete picture. In the computer we can simulate changes in muscle strength to mimic the changes associated with ageing, measure its effects, and directly test strategies and treatments that can help improve locomotor performance. This "in silico" approach fills the gap that is left by purely experimental approaches and allows us to get a much more complete understanding of locomotion for both practical and purely theoretical reasons.