When I first got Red, he had a huge brace built in. Any time you asked him to do something new, or he was worried or stressed, the brace showed up. Its usual form was that he would raise his head, inverting his body, and bend to the right - unless you did something to change things, it was like having concrete in your hands and his body would be stiff as well. There was often a brace against moving forward as well - a balk - although the brace could show up when he was moving forwards as well.
One of the reasons he stayed up with my trainer Heather for 90 days was how imbedded this brace was. Every time he was asked to do something new - even if the brace had been absent in the recent work - the brace would show up again and would have to be worked through. Red's pretty much past that now, although if he's really worried it can show up momentarily.
The one place where the brace has been more persistent is, oddly, in the first walk/trot transition - all walk/trot transitions after the first one are just fine even if the first one is braced/balked. It's almost like a bad habit. If there's any tension at all in my ask, I get the brace/balk, or else he bursts through that directly into canter - it's like there's a barrier there.
I'm pretty certain that it's a learned pattern of behavior, but that doesn't really matter. I'm part of the problem - the natural reaction to a balk is to push, which just is a counterbrace, which intensifies his brace/balk in response. I have to have him soft and relaxed and just think/lead him into trot for it to work.
The past few days Red and I have been riding bareback at the walk, since he's lame. He insists on this - he's not content to just hang out in his stall like most horses would be. Since he's sound at the walk and seems happy about it, I oblige him. Most rides, we take a few steps of trot - it seemed a bit better today, but I'll put him on the lunge Thursday to see if it's really better. Now the odd thing is that, when I'm riding bareback, the walk/trot transition just flows - no balk, no brace, even though he's probably a bit sore. It's clear I'm doing something differently when riding bareback than when I'm riding in a saddle.
I think it's a combination of my posture and my legs. My posture riding bareback is inherently better than when I'm in a saddle - I really can't lead forward when bareback - so the front end is freer. I can have better posture in the saddle and I've been working a lot on that. And I rarely use any leg when riding bareback - my lower leg swings freely while my upper leg is in contact with the horse. I think Red reads lower leg cues as braces and braces against them, and this is partly where the problem is coming from.
Three days in a row we've had absolutely flawless first walk/trot transitions bareback. Now I have to duplicate that in the saddle once we're ready to do more trot work. Funny how it's almost always what we do that creates a problem, isn't it?