Running is a method of terrestrial locomotion by which humans and other animals move rapidly on foot. Running is a gait with an aerial phase in which all feet are above the ground. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight, and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity. The term "running" can refer to a variety of speeds ranging from jogging to sprinting.
Marathon runners at Carlsbad Marathon, US, 2013
Ancient Roman bronze sculptures of runners from the Villa of the Papyri at Herculaneum, now in the Naples National Archaeological Museum
Eadweard Muybridge photo sequence
A U.S. Army soldier wearing sportswear runs to maintain his fitness.
Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity.
The velvet worm (Onychophora)
A jumping kangaroo.
Helix pomatia crawling over razor blades. Terrestrial gastropods crawl on a layer of mucus. This adhesive locomotion allows them to crawl over sharp objects.
The pangolin Manis temminckii in defensive position.
