[airair]

I still don't understand how it is possible to roll the left forearm to get additional force/speed (as the 4th source as shown in the video) without it being a hinging motion. When the left arm rolls - why isn't that a horisontal hinging? Is it a movement of the left forearm that is identical to a horisontal (or angled?) hinging, but is called something else? The left arms doesn't move and not move at the same time? And if it moves - how can one roll the left forearm in different ways - it turns to the left doesn't it? How does this work with a angled hinging - how does the left forearm turn in this case? Who is bright enough to explain this in an understandable way?