Beach Girl Running

Humans leap from one leg to the other while running. Each leap raises the center of gravity during take-off and lowers it on landing as the knee bends to absorb the shock. At mid arc, both feet are momentarily off the ground. This continual rise and fall of bodyweight expends energy opposing gravity and absorbing shock during take-off and landing. Running uses more energy than walking to travel the same distance. Therefore, running is less efficient than walking in terms of calories expended per unit distance, though it is faster. In 2004, scientists at the University of Utah and Harvard University hypothesized that the ability of humans to sustain long-distance endurance running may have been instrumental in the evolution of the human form.