How do I train a horse for the back-through straight chute obstacle?

The straight back-through chute — two parallel poles or rails that define a narrow corridor the horse must back through cleanly without touching either side — is one of the most common trail obstacles and one that clearly reveals the quality of the horse's backup and its responsiveness to individual leg aids for straightness. A horse that backs through a straight chute without touching either side is a horse with a confirmed, straight backup driven by hind leg awareness and lateral leg responsiveness. The prerequisite for the chute is a horse that backs straight in open space from light, consistent rein pressure with leg aids available to correct drift. Building this open-space backup first, with emphasis on straightness from the beginning rather than adding it as a correction after drift appears, develops the muscle memory and responsiveness that the chute obstacle requires. A horse that has backed straight a thousand times in open space brings that habit into the chute; a horse that has backed crooked in open space will back crooked in the chute as well, with the added complication that the chute makes the crookedness immediately visible and costly. Begin training the chute by making it wide enough that the horse has room to drift slightly without touching the poles and backing through it with emphasis on straightness from the first repetition. As the horse demonstrates consistent straight backup through the wide version, gradually narrow the chute by moving the poles closer together until it approaches competition width. The narrowing process should happen over many sessions rather than in a single session, giving the horse time to adjust its awareness to each new challenge. Stopping the horse midway through the chute and asking it to stand before completing the backup teaches the horse that the chute is not a situation to be escaped quickly but a task to be completed carefully, which directly addresses the rushing tendency that many horses show when backing in confined spaces.