Let’s look at how moving in a circular way can produce effortless power.
If you rotate a circle then different parts on the circumference will move in different directions relative to each other. This is crucial to the art of Tai Chi Chuan. Let me explain.
This video of rollback from Yang style is very nicely done. Although I don’t speak Chinese, so I have no idea what he’s saying, the application is nicely shown and very clear.
Let’s take a circle.
Notice that the two points in black on the outside that are directly opposite each other.
If you rotate the circle clockwise, or anti clockwise, then the two points will rotate relative to each other. And from the perspective of the centre of the circle, they will be moving in opposite directions.
Now, if you imagine the circle is the view of a Tai Chi practitioner in the video of rollback, but viewed from above, you can see that if they rotate around their centre then the parts of the body on the opposite sides of their circle will be moving in opposite directions.
Now, unless they are spinning constantly, they won’t keep this up for long in the same direction, but it will be happening continually throughout a Tai Chi form, just in different directions and with different parts of the body.
So, while his left hand is rotating backwards to the left, clockwise direction, his right shoulder is moving equally forward to the right, still clockwise. They are the points on opposite sides of the circle. Obviously he then hits the limit of his rotational possibilities (without stepping) and stops.
Obviously Tai Chi is more of a sphere than a flat 2D circle, but hopefully the point stands and shows how circular movement around the centre point can produce power from the whole body.