What does it mean when a horse is late behind in the lead change and how do you fix it?

A horse that is late behind in the flying lead change — that changes its front legs in one stride but does not change its hind legs until the following stride — is executing what is called a cross-canter or a swap that is late behind. This is the most common lead change problem in western performance horses and is one that Clinton Anderson addresses specifically in his training program. The late-behind change occurs because the horse has learned to respond to the rein-and-weight change aid with its front end but has not learned to change through its entire body simultaneously. Often this happens because the horse was rewarded for the front-end change before the hind end was consistently following, or because the horse is not collected and balanced enough at the lope for the hind end to respond simultaneously with the front. Anderson's correction addresses collection first. A horse that is strung out and heavy on its forehand cannot change behind in the same stride as the front because the hind end is too far behind the body's center of mass to receive and respond to the change signal in the same moment. Developing more collection and engagement of the hindquarters — through transitions, collection exercises, and specifically working on the horse's ability to carry itself at the lope — gives the hind end the position and engagement needed to change simultaneously. The specific correction for the late-behind change under saddle involves using the new outside leg with more energy at the moment of the change request — specifically driving the outside hind leg forward and under to change. This outside leg becomes the signal to the hind end that the change is happening now, which coordinates the hind change with the front change that the horse is already executing reliably. Patience is required — late-behind changes that have become established habits may take months of correct training to eliminate, and rushing the correction often produces tension that makes the problem worse.