Let's exampling whether "internal" sparring is practical or not. Let's have a simple definition of "internal" as
- You use your waist (Dantian) to push/pull your arm.
- Your body function as one single unit. When you move, all body parts move. When you stop, all body parts stop.
If you use your waist (Dantian) to push/pull your arm, since you have to move your waist first before the power can be sent to your arm, there is always a small delay between your waist motion and your arm motion. Can you afford that small "delay" in combat?
I has tried to let my waist to push/pull my arms. This way my opponent can only see my body movement but can't see my arms movement. It's good to express Shenfa and feel great too. But when I see my opponent's opening, I start to move my waist, when my waist pull/push my arm and my arm push/pull my hand, my opponent's opening is already closed.
In the following clip between 0.58 to 1.10, you can see CXW faiji in combat speed.
http://www.youtube.com/watch?v=MrF_o9BdJ4M
Is CXW moving fast enough? Within 12 seconds timeframe, he did 14 moves. That's average 12/14 = 0.86 second per move. To me, this kind of speed is far from "combat speed". If CXW's opponent only drops his guard for 3/4 (0.75) second, CXW's punch will miss his opponent's head.