知识百科：走路时为什么要摆臂
我们在走路的时候手臂会不自觉的随着步伐前后摆动，而且还很有规律地在摆动，比如左脚出右手之类的。那么，这样自然的动作搭配是为什么呢?It's all part of a fine-tuned dance of physics and engineering. The
skeleton is made of long bones and the many-jointed spine which alone cannot
support the body against gravity. Coordinated muscle activity enables it to
stand erect. Man is a very tall structure balanced on a small base, with a
rather high center of gravity just below the small of the back. For stability,
the center of gravity must be kept within the small area determined by the
vertical projection of that base. Reflexes and postural mechanisms allow us to
maintain equilibrium under unstable conditions produced by movement. There are
no "center-of-gravity" receptors to provide afferent input, but rather afferent
signals from muscles, joints, skin, vestibular system and eyes provide
integrated information about the location of the center of gravity, sort of an
internal map or positioning system.
In walking, the body is balanced on the base provided by one foot. The
weight is supported alternately by one leg and then the other, so the body moves
from side to side to poise the center of gravity over each leg in turn. As this
happens, the foot is raised and advanced and the trunk sways to counterbalance
the weight of the leg -- as the hips sway, the arms must move out of the way,
and there is also some natural propelling of their weight from the shoulders.
All of this is so delicately coordinated, rhythmically and gracefully within the
brain. You may notice that when one becomes self-conscious of this process, one
may try to inhibit the natural movement as one becomes ultra-aware of it,
producing a stiff-armed effect. By focusing only on, say, the arms swinging, one
loses the fine coordination of all of the movements.
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