Join Date: Dec 2010
Location: southern Arizona
If you are bracing against the stirrups, stop. Make a point of consciously relaxing your legs. Personally, when I braced with my legs - and I've done it plenty - I also grip with my knees. So if I try to pry my knees apart while riding, my legs have to stop bracing.
If no stirrup work isn't an option, try to see how light you can be in the stirrup. Try to ride with your feet barely touching the stirrup. Riding my mare stirrupless isn't a real smart option, but riding her with my feet barely touching the stirrups is!
When I started riding, people told me my toes should be forward. That always resulted in a stiff, braced leg for me. So did hearing "heels down". And when people told me to put weight in my heels, I did it by pushing down my heels - which also resulted in a braced, tense leg. The right way to have 'weight in your heels' is to keep your leg loose, so the weight flows uninterrupted into your heels.
If you can post pictures, it would help. Some of it depends on how you are built and what horse & saddle you ride. My daughter's favorite saddle puts me in a severe chair seat & makes my knees ache after about 20 minutes...but she loves the saddle.
"People can teach us the rules, but only horses can teach us the art of riding."