The information being passed isn't just nerve signals.

Basically, imagine a human body as being like a whip. If you take parts of the whip and make them stiff, then you can't crack the whip. The whip in its pliable form is capable of conducting a wave down its length. The whip with a stiff section can't conduct that wave.

In the whip, this wave is its "chi". A stiff section of the whip blocks its chi from flowing. It has a chi blockage. If the whip's chi channels are open, then it can be cracked.

The more of your body you can recruit into each movement, the more efficient that movement is. I believe that different parts of the body "communicate" (more precisely they respond to one another's actions) via tension and pressure. When a section of your body is stiff, that tension and pressure is less readable across that barrier. Your neck muscles will have a harder time predicting and responding to -- and ultimately optimizing -- the actions of your quadriceps, for example, if your trunk doesn't convey the mechanical "signals" well enough for your neck muscles to tell what's going on at the other end of the body.

To understand what I mean about responding, think of the way your body wobbles when you stand on one leg. That's tons of muscles in your body responding to information about your balance point. Your gut muscles might clench for a fraction of a second in response to your knee detecting that your leg has become less stable. Just an example. This action is coordinated, classically, by peripheral ganglia of the nervous system. But I believe it also relies on mechanical signals -- waves of pressure and tension, because mechanical signals conduct faster than nerve signals. (nerve conduction is about 50 m/s, speed of sound in the human body is about 1500 m/s)

Think of a flock of birds. Those birds each carry about a swarming algorithm: they make real-time decisions based on the positions and velocities of the other birds. The result is a flock that moves like an intelligent amoeba in the sky. Now imagine if you created some visual barrier in the middle of the flock. Now the birds on one side of that barrier can't effectively swarm with the birds on the other side. The flock has been split into two flocks. That visual information is the flock's "chi", and the blockage makes the flock less integrated.

Various body parts -- muscles, organs, nerve ganglia, senses -- are a swarm, and a chi blockage is something that splits that swarm into two or more smaller swarms.