I attended my first couple of MMA classes at the end of summer 2020 and I got some excellent real experiential feedback on the importance of one of the foundational principles of Tai Chi, namely feng song (release the joints), and specifically song in the shoulders. That is keeping the shoulder joints loose and sunk into their nest, not raising the shoulders.
In the class a guy managed to off balance me and throw me down by utilising an underhook in an 'over-under' clinch position. In another exchange during a wrestling class, someone managed to toss me over their back my pulling my arm in a judo style throw. I was initially disappointed because, for a Taijiquan practitioner we aim to be well rooted and difficult to off balance, and I had felt relatively confident in this aspect before these experiences.
But then I realized this was shining a spot light on one of the weakest aspects of my skill in Chen Taijiquan. When I first started Tai Chi, my shoulders were very tight, and hunched upwards somewhat. I have spent the last few years opening and stretching the muscle and fascia in my shoulders and upper back to allow my shoulder joints to sit in a more relaxed and neutral position. But I still struggle to maintain 'heavy arms' and 'released shoulders' at all times during the laojia form, often finding my shoulders have risen, my arms have become 'light', and so I need to consciously and deliberately 'let go' again. And certainty under pressure and at a high pace in a live environment, I'm sure my old habit of raising the shoulders creeps back in unconsciously.
When the shoulders are raised and the arms suspended, it breaks the connection (peng) from the arms, through the shoulders, and down into the back; and so the ultimate root into the floor. This means that the integrity of my posture can be broken much more easily. And once my posture is broken my body is far easier to manipulate, because it becomes a series of connected parts, rather than a responsive whole.
If the shoulders have plenty of song and the arms are heavy, thus connected with the torso, when someone tries to off balance me with an underhook, rather than my shoulder rising thus breaking my posture, they should feel the weight of my whole body sinking against their underhook. Once the connection is lost at the shoulder joints, then their underhook will raise my arm, and in doing so my shoulders will lose their connections to my hips, my spine will bend, and my whole posture will lose its integrity. I realised this is what had happened in these instances.
So I now had clear firsthand feedback that I needed to keep working hard on this aspect in my Taiji training. I stopped attending classes after just a couple of weeks due to Covid lockdowns, so I have now had 10-12 months to work on this in my Taijiquan training. I’ve now started up again with the MMA classes, and have been attending for a couple of months, and have noticed a big improvement