Do flying changes require collection similar to shoulder-in?

Flying changes and shoulder-in both require collection, but they require it in different ways and to different degrees. The collection required for shoulder-in is primarily lateral — the ability to bend through the body, engage the inside hind in a carrying role, and travel on two tracks while maintaining rhythm and forward energy. The collection required for the flying change is primarily longitudinal — the ability to be light on the forehand, straight through the body, quick off the hindquarters, and responsive enough to change the footfall sequence through an entire gait in a single suspended moment. The specific collection that flying changes require is best understood by examining what actually happens during the change. The horse must be light enough on his forehand that the front end can reorganize freely during the suspension, engaged enough in his hindquarters that he can push off cleanly from the departing lead and land correctly on the new lead, and balanced enough through his body that the change does not produce a disruption in rhythm, straightness, or tempo. A horse on his forehand cannot do any of those things cleanly — a heavy forehand reduces the suspension and produces the disunited or four-beat changes that indicate the horse is changing in front before he changes behind. Shoulder-in prepares the horse for flying changes through several specific mechanisms. The inside hind leg in shoulder-in is being trained to step under the body and carry weight in exactly the way it needs to step under and carry during the landing stride of a flying change. The suppleness through the horse's topline that shoulder-in develops is the same suppleness that allows the horse to reorganize his body cleanly through the change. And the responsiveness to the leg that shoulder-in requires is the responsiveness that the flying change cue depends on. The training sequence that arrives at reliable correct flying changes most efficiently runs through shoulder-in confirmed on both reins, haunches-in confirmed on both reins, counter-canter confirmed through increasingly demanding figures, simple changes through the walk confirmed with clean transitions, and then finally flying changes introduced when all preceding elements are solid. Each element develops a specific physical or communicative quality that the next element requires.