From Mugwump
http://mugwumpchronicles.blogspot.com/2008/09/qs-and-as-and-laura-crum.html
Smurfette said,I am still battling the issue of the lead changes with current horse, though. I worked on your detailed instructions and certainly wore MY legs out, moving his hips around, but I think I don't get to work him consistantly enough (so far this year its been hurricanes, a bite on the back and now an abscess) to progress, or do some horses just never pick up this skill? This is the first horse I have ever worked with who won't at least learn to make a rough change on cue.Some horses are not good lead changers. It's a fact. They don't all switch naturally even running with their pals in the field, and some are just one leaded. Sometimes conformation issues, back or leg pain can cause it. Sometimes they are resistant to the rider pushing on them.That said, you can try a couple of other things.First lope a circle to the left. Make sure your weight is in your right stirrup and hip pocket. Stop your horse in the middle of the arena, where you would normally change for a figure eight. Walk the horse forward in a straight line about 4 or 5 steps. Dramatically shift your weight to the left stirrup and hip pocket. Ask for a right lead from the walk.Lope a circle to the right. Make sure your weight is to the outside. Stop in the middle of the arena. Walk forward in a straight line about four or five steps. Dramatically shift your weight to the right stirrup and hip pocket. Ask for the left lead from the walk.It's important that the horse lope off from a straight line, not into the shape of the circle. Begin your circle once the horse has his lead.Repeat this exercise for several days. It doesn't have to be continuous, but you have to keep it slow, clear and calm. Give your horse time to think. Do it at least ten times for each lead, every time you ride.Also try backing him in a circle. One to the left, one to the right. A big, perfectly round, with the horse in a "C" shape circle. Start with a step or two, move his hips with your leg, take another step or two. This will help develop softness in both of you, and make it really clear where your horse's stiffness lies. When you can guide him through a backing figure eight with clear cues and no resistance, your lead changes will become a lot easier.Now back to the lope stop change exercise. Your horse will begin to anticipate the change of direction. Keep him straight, but make the amount of walking steps fewer and fewer. Encourage his anticipation. If he tries to change, reward any small effort. Be patient.When he changes (even if it's ugly) let him come gently down to a walk, and walk him on a loose rein. Be happy with one change each way for a very long time.