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

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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.