Running is a method of terrestrial locomotion by which humans and other
animals move quickly on foot. Running is a gait with an aerial phase in
which all feet are above the ground (though there are exceptions). This
is in contrast to walking, a slower form of movement where at least 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.
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