Dressage in draw reins

John thought Duke might need to be worked in draw reins, so I brought them with me so that he would be there for the first use and remind me how to ride properly in them.  Duke didn't make a big deal out of it, and John suggested I ride him twice a week in them, but start with them a little loose and only tighter up if he ignores them.
We got some really nice effort out of Duke with them on.  I would describe it as him lifting his back up and balancing, but it made him really tired - he was clearly working much harder, and he could only sustain it for a few steps at a time.
We started with just some 20 meter trot circles, and John had me tighten the draw reins until we got a bit of bend in Duke.  From there, we went to 10 meter trot circles, and John made things a bit more nuanced, with a bit of inside bend, some loosening of my arms, leg on to keep him moving forward, inside leg to encourage him to bend around his ribs, and some inside leg on the "inside" of the circle (without the arena wall) to encourage him to use his inside hind leg to step under himself.  I had a hard time keeping the circle 10 meters, but John said it was ok because it was more important that Duke was bending and pushing himself off the inside, and the circles were still round.
Then we worked on canter, going straight to it on the 10 meter circle.  In the draw reins, it was harder for Duke to pick it up - he wanted to kind of shuffle into it - but man, when he stepped under and balanced, I could feel the difference in his back immediately.  He did decide, once, for no apparent reason, to spook at the same things that had been in the corner the whole ride, so it will be interesting to see if that is something he does once he's working hard to try to get out of work.
When he hesitated in the canter, John said I can either use more seat or more leg, and he, fortunately, makes the feel really obvious so I have plenty of advance warning and can ask him to keep going.
Here, especially to the right, we did a bit of inside hand to the inside, and John said especially if he was stiff all week (which he was, consistently to the right).
Then we did a bit of shoulder in.  John had us start on the circle, and, for shoulder in to the right, my left hand came over to but stopped at his neck.  We did it on the circle, and then down the long side, and Duke did that pretty well too.  It seemed a lot easier to do in the draw reins than without them, but maybe that was also partially because he was moving well by that point.
John suggested when he's having a stiff day, it's ok to work a little more on the stiff side, but do it about 60/40, not like all on the stiff side and ignore the soft side.