Walking and Running

You are walking along, going to an appointment, when you realize that you a n rather late. You walk faster, and then faster still. You may double your speed, but your pattern of movement remains the pattern we call walking. Then, suddenly, you break into a run, an obviously different pattern of movement. Why did you do that? Why use one technique of movement at low speeds, and a dramatically different technique at high speeds? The change is made at a very predictable speed-about 2.5 meters per second (6 miles per hour) for normal-sized adults. This paper will examine why this is so by analyzing the two patterns of movement. As Figure-1 shows, walking involves each foot being on the ground for slightly more than half the time, so that there are stages, for example staged, when both are on the ground simultaneously. While a foot is on the ground, its leg remains fairly straight; therefore, the trunk is highest when the Ieg is vertical. This occurs at stage 6, when the trunk is passing over the supporting foot. The trunk is lowest at stage d, when both feet are on the ground. Figure 2 shows running, during which each foot is on the ground for less than half the time, so that there are stages, such as stage d, when both are off the ground. The person is traveling in a series of leaps and must therefore be highest in mid leap, at stage d. His supporting Ieg is bent at stage b, as the trunk passes over the supporting foot. The trunk is lowest at this stage.