The position and shape of the pelvis changes dramatically depending on whether you are in a parasympathetic or fight flight nervous system state. In the sympathetic state, the entire rim of the pelvic bowl folds in and up, and it’s from this position that most of our instructions are the seat are given. The amount of us living dominantly from our fight flight systems has become so vast that we’ve come to accept and recognize the pelvis being in this position as the norm.
The resting place of the pelvic organs also will have a dramatic effect on weight distribution and pressure in the saddle. In the parasympathetic, the bladder would sit behind the pubic symphysis and bear weight on the cartilage, acting as a stabilizing force. It runs an energetic line somewhat like a half pipe towards the tail.
In the fight flight system, however, the colon starts to shift forward, tucking the tail; the bladder starts to lift up. As it’s fascially attached to the pubic symphysis, this starts to lift up too.
This has a flow on consequence for the abdominals; the pubic symphysis is attached to both the rectus abdominis and the linea alba and as the bladder starts to rise up, it causes the fibres of the abdominal muscles to overlap, altering their homeostatic length and making them incapable of contraction.
All of this occurs to bring the organs close together for both protective purposes and also for efficiency; if the organs are grouped together, the body doesn’t have to work as hard to pump blood to them.
If you lie flat on your back, you can gain information about where your pelvic organs sit by gauging where you feel the most weight. If the top of the tail and sacrum meet is where you feel the pressure (the top of the tail is where your butt crack is, or where the glutes start to part), then the bladder is most likely low.
If you feel the weight higher, it tells us that the colon is more weighted down and the pelvic organs are sitting higher.
As your organs shift, your weight shifts. Organ position directly affects your centre of gravity and ability to maintain an open and stable posture.
The biomechanics and sensing work I do in my membership program, JoyRide, allows us to establish adaptability and responsiveness in the nervous system so that the structure of our body is free to take up the most optimal positioning. If you are interested to read more or work together, you can check it out here