First of all, gripping is a very strong survival reflex.
It is hard to kill it completely because it goes off before our brain can stop it.
Second, until your core is stable you will grip occasionally here and there. Do not get discouraged
and work systematically on your core strength and your thighs position.
The correct breathing and core strength is vital for your arthritic spine.
Make sure your stirrups are appropriate length. The length depends on your legs, type of your
saddle and size of your horse's barrel.
Read articles about rider's posture on my website.
At home, use the exercise ball to sit on it sideways to a mirror. Sit on it in such a way that the ball
is between your thighs, knees pointing forward and down and almost touching the floor (you need large
enough ball to keep them off the floor). Lower legs are pointing backwards laying on the floor parallel to
each other. Pelvis in in neutral.
Look at yourself in the mirror and notice how your thighs are flat on the ball and knees are pointing
forward not outward. That is what you want to achieve in the saddle. If it feels uncomfortable in the groin
area or hip joints you need to work on stretching exercises
. Just sitting like that on the ball is already a good start.
If you feel comfortable create an abdominal push
and start bouncing on the ball up and down.
Watch yourself in the mirror, your core should not wiggle and your thighs should lay flat on the sides of
the ball. Focus on the moment when you sink down and see your thighs spread. Now, consciously grip
with your thighs when you go up, relax to go down and grip when you go up. Notice how much more
you are bouncing now. same process happens in the saddle.
Next, do not grip but consciously keep your thighs spread apart
slightly (without changing their position) even when you go up in your bounce. Feel how much more you are connected
to the ball and there is only as much bounce as you have created yourself.
If you find it difficult to keep your balance on the ball and feel yourself falling off sideways work on abdominal
push, even weight distribution under your seatbones and stabilizing the thigh opposite from the direction you
are falling in. Stabilizing doesn't mean gripping but giving it enough tonus not to be displaced much by the
movement of the ball (or horse for that matter).
Remember, you do not bounce on the horse. You let horse bounce under you.
I'm looking forward to working on your video.