The elbows are not held too close to the body. They always create a circle with peng in the form, with push hands, with silk reeling, with standing post. Stretch out from the back to make the peng circle with the arms. Check for the elbows, do they need to drop, even slightly to become peng. An elbow that is even slightly lifted or turned outward too much is no longer peng and creates a vulnerability and a stiffness. If stiffness occurs in any of the joints then they are not open, are not peng and do not allow energy to flow through the body. When the elbow is stretched out and dropped the elbow will feel like a brick. An elbow that is dropped, correctly, will open the shoulder. The chi will move to the arms and to the hands which will become warm and/or prickly.