Even if you don't like martial arts much, watch
this video and check out this guy's power.
At the 0:20 mark, he clearly references turning
his waist to create whole-body power-- which
extends out to his arms. In kinesiology, this is
called the "Serape Effect."
The Serape Effect is the coordination of the
trunk and the extremities to create incredibly
powerful movements like a pitcher throwing
a 90-mile-per-hour fastball, or a football
player kicking the ball way down the field.
You have to watch the movements in this
video very closely to see that coordination
and power originate at the waist, and that
the rest of the body has to follow along.
The only way to get it all to work is to
relax deeply, and control the body with the mind.