The straight palm gets its power from the twist of the waist and the driving of the body behind the thrust, like any other thrust, but the upward palm requires that the elbow be bent and that the hip be directly behind and in-line with the strike od it becomes simply an arm strike. This requires that the body be slightly out and away from the arm.
Originally posted by Justme
where does the power come from? I mean isn't MOST of the power generated by twisting the waiste into the strike. Example, Bas Rutten when he was smacking Shamrock on the ground with the palm wasn't most effective because he couldn't generate power through his whole body.