So anyone who has wrestled or practiced BJJ should have a fair idea of how being relaxed lets you transmit more weight into your opponent. In particular, resting the weight of your torso directly onto your opponent's torso so that the opponent has to hold you up as well as themselves.
Side control for example is a good example of the guy on the bottom holding up his opponent's torso's weight. When the guy on top is relaxed it makes it hard for the guy on the bottom to breath.
It is only more recently that I have been able to get not only the weight of my arms, but some
of the weight of my torso into my partner through a tremendous amount of relaxation. If I try and add to the force generated by my arms with my arms it lessens the amount of weight my partner has to hold up and makes my arms feel lighter to my partner. Likewise I have to make sure that this weight is directed straight down into the ground
; I can not be leaning or committed, nor can I try to be pushing into my partner. If I do this right, my opponent/partner quickly fatigues if they try and hold my arms/upper body up with their own muscles. If they can counter it with their own weight then it stays in equillibrium, much like two concrete slabs leaning into one another.
Now the way to test this is fairly simple, if you are familiar with the aunkai pushout
exercise, you know that if someone is leaning, you can pull away and they fall forwards because they have committed their weight forwards instead of keeping it down. A similar thing may happen with the arms, if your arms are tense and your partner pulls away, your arms will stay up. If your partner pulls away and your arms drop, just like a weighted chain would when you unhook it from a pole, then your arms are relaxed.
Anyone who has had the opportunity to attend one of Mike Sigman's workshops is familiar with the concept of a ground path. If you have not, I highly recomend it to get a foot in the door to understand what these skills are. As a quick review, you basically let your opponent's push passively transmit through your body rebound off the ground (ala Newton's third law) so that your opponent is pushing the ground via your own body. I assumed this was along the lines of what was meant by peng jin. For a long time, I played with trying to add something to that push. I knew from the aunkai pushout exercise that pushing back with the arms and shoulders only pushed myself away so I tried pushing back with other parts of the body.
(the famous diagram)
I tried pushing with the legs, I tried pushing with the lower back. I learned that if I could move the force from the lower back to the core area I could take more force, but not exactly push back along the same path. If I used structure, I could push back along the same lines with my legs, but I was sure this wasn't really what was meant in Mike and Dan's discussions. More recently thanks to the guidance of a fellow student in the DC area who has helped me signifigantly relax my upper body (still have a way to go, I can only relax down to the sternum), I have learned how to get under my arms. Namely, how to support my arms with the middle of my body. In particular this means that when someone pushes my arms I feel the load in the the crotch area. This seems a bit different from a groundpath where when I had good structural alignment and someone pushed I felt the the pressure increase in my feet.
It seems that when you combine relaxing the weight of your upper body on your opponent and commiting your weight straight down (no leaning) with supporting the arms from the crotch is the additive I needed to cause my opponent to push themselves away.
Now I have a question for far more experienced people than me, feel free to PM me if you like.
As I said earlier, I feel this load in the crotch, in particular the kua as shown above or the perineum, but definitely more the kua. I don't generally feel it in the area associated with the dantien. Is this because the muscles in the crotch area are so weak that they need to be built up first? Am I focusing on the wrong thing or you will wind up feeling the loads in a number of places in the lower torso.