One of the easiest ways to begin to develop the stiff side of the horse is in the aisle, every time you handle your horse .
Use your knuckle as if it were a Prince of Wales spur and ask your horse to bend. Hold the halter up close and control the nose. Be flexible with the nose, if that is stiff, flex the poll, and then use your knucle "on the girth" to ask the horse to bend away from you and move his rear end over. He will need a little space to move forward so he can cross his feet over (better in front than behind, keep that forward thinking going).
Work all turns in the aisle this way. Work more often on his stiff side.
Within a month your horse should be bending very well, and it should help him with all of his under saddle work.
There are several things you can try, depending on what is causing the issue. One thing my trainer has me do is, keeping inside (stiff side) leg on at the girth, open inside rein. Do NOT hold rein - rather open, using leg to prevent falling in, then give. You want to ensure horse is forward and not getting behind the leg when doing this.
Another thing, if caused by balance issues, is stepping into the outside (flexible side) stirrup (when stiff) then once corrected return to proper position.
If horse is throwing you onto stiff side sitting with butt to flexible side can also help (again - balance issue).
Shoulder fore (especially to the stiff side) helps build up muscle for balance issues and (of course) is a straightner is stiffness is caused by horse bracing against being straight.
Bending also helps stiffness so some 10 meter circles using inside hip to outside rein will also help.
I usually try a few things as my smart mare, once she figures out how you have "fixed" something, looks for another way to evade - until either she or I give up (usually she gives up first - but there have been those days).
Last edited by Valentina_32926; Jan. 9, 2013 at 08:23 AM.
My instructor gave me this tip (my horse is stiff, too, on one side): From the ground, do a turn on the forehand (front feet stay as still as possible and inside hind steps over) and be sure the hind is stepping UNDER the body, not behind the other hind leg, she even pushed that hind while she was asking for the turn.