"trotting" was common in events. Speed walking is the general term for fast walking. Within the Speed Walking category are a variety of fast walking techniques: Power Walking, Fit Walking, etc. Power walking is the act of walking with a speed at the upper end of the natural range for walking gait, typically . To qualify as power walking as opposed to jogging or running, at least one foot must be in contact with the ground at all times. Racewalking is a long-distance athletic event. Although it is a foot race, it is different from running in that one foot must appear to be in contact with the ground at all times. Stride length is reduced, so to achieve competitive speeds, racewalkers must attain cadence rates comparable to those achieved by Olympic 800-meter runners, and they must do so for hours at a time since the Olympic events are the race walk (men and women) and race walk (men only), and events are also held. See also pedestrianism above. Afghan walking: The Afghan Walk is a rhythmic breathing technique synchronized with walking. It was born in the 1980s on the basis of the observations made by the Frenchman Édouard G. Stiegler, during his contacts with Afghan caravaners, capable of making walks of more than 60 km per day for dozens of days. Biomechanics Human walking is accomplished with a strategy called the double pendulum. During forward motion, the leg that leaves the ground swings forward from the hip. This sweep is the first pendulum. Then the leg strikes the ground with the heel and rolls through to the toe in a motion described as an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground. While walking, the muscles of the calf contract, raising the body's center of mass, while this muscle is contracted potential energy is stored. Then gravity pulls the body forward and down onto the other leg and the potential energy is then transformed into kinetic energy. The process of human walking is able to save approximately sixty-five percent of the energy used by utilizing gravity in forward motion. Walking differs from a running gait in a number of ways. The most obvious is that during walking one leg always stays on the ground while the other is swinging. In running there is