CMA is both...but anyway.
What makes you so certain that the Long Fist punch IS EXTERNAL (only) ?
I've been giving this simple guideline away for years and people always want to make it more difficult.
How to tell the difference in ANY method.
If the chest is more puffed up and / or full of tension during a movement (than your lower Dan Tien) = it is more external in nature.
* When I say chest puffed or full of tension...think of a person standing in attention military style...a bit over exaggerated but you get the idea.
! You cannot effectively DO BOTH. Meaning you cannot be full of energy or tension (and air) in the CHEST..AND at the same time be full of energy and have compression down to keep the dan tien FULL (like a dense ball) It must be ONE is more than another.
In Taiji for example, you always have the upper chest bow cavity more relaxed and the Dan Tien more full. That is the nature and one way to discern an internal method.
Look at this guy blocking on the right:
His chest is definitely MORE FULL than his lower dan tien...ergo it is a more external method.
- It is easy to tell and point out. The way his left arm chambers, the elbow pulls back the left back scapula.
- the way he is linking his right blocking arm to his left makes his chest MORE full than his dan tien.
AGAIN...you do not and cannot consistently keep the UPPER Chest and lower Dan Tien FULL of energy simultaneously. That's not how CMA works. It is one or the other, it switches from upper to lower and back again. Yin / Yang.
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Experiment for you John
In your moving GIF holding the bricks...it looks pretty standard and could also be the final pose or brush knee Left palm (or punch for all I care)
Hold the final punch posture the same way it ends in your gif. Have your student structure test against the direction or your strike. Which way will hold off your student better?
If you relax your chest / shoulders and sink your elbows (as you are doing in the gif) meaning your dan tien will be more full
OR
If you put tension in your chest, (Flex your pecs if you want to) experiment with feeling your upper chest more full than your dan tien. It won't work this way, a strong push against the structure will give you more trouble this way.
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If in the same example...you chambered up your right arm and pulled your right elbow back...it will more it easier to do it more externally.