Why is it important to keep track of the Rib Cage?

You know as a rider every time you ride a horse or another horse you get a new insight.  This one started in May when I showed Hazel 2nd level. 

At the horse show I decided that I did not have enough suppleness in my horse laterally.  The shoulder In to Renvers maneuver illustrates that really well.  So for the past month I have been working to get Hazel more supple behind the saddle.  I had done this pretty well but she was still a bit sticky in her flying changes.

I have another mare, Bacara ,  that I have shown 4th level but she had time off due to a foal and a hoof abscess that lasted forever.  Because Bacara's initial training went slowly but steadily forward - she gained muscle gradually and I introduced movements gradually.  Well now that her vacation is over she still remembers everything and wants to do everything.  Her most favorite thing in the world is flying changes - she just plain likes them.  But now her muscle tone is lacking which makes her rib cage more easily movable side to side.  Lets just say in the canter she will fly a change every time her rib cage moves too far laterally.  It is a weird feeling having the knowledge there without the muscling to go along with it.

I thought back to Hazel and understood that she is shorter coupled and rarely moves her rib cage anywhere.  Hazel likes to hold her ribcage slightly to the right.  Hmm!  So I started asking for suppleness in her ribcage and that has helped Hazel's flying changes! 

I guess this is a plug for educating your feel and accepting the gifts of an accidental vacation on an advanced horse.  The understanding of the ribcage position has helped me immensely.  Thank you Bacara!