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 (though there are exceptions).[1]
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.[2] 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.[3] The term "running" can refer to a variety of speeds
ranging from jogging to sprinting.
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