Opening the door exercise
Open the door exercise combination training. |开门动作练习组合。
Master Chen has uploaded a more detailed video demonstrating an exercise to develop the hinges. It is based on move 79 in Yilu turn and lotus kick, with an additional rotation to develop the hinge on the left side of the body.
http://practicalmethod.com/2010/07/the-hinge-online-video-purchase/
Source: https://practicalmethod.com/?p=4899