How do you use a martingale and what is it?

A martingale is a piece of tack designed to limit how high a horse can raise his head, preventing the horse from throwing his head above the point where the rider loses effective rein control or where the head position creates a safety risk. There are two primary types — the standing martingale and the running martingale — and while they share the goal of limiting excessive head carriage, they work through different mechanisms and are appropriate in different contexts. The standing martingale is a single strap that runs from the girth, through a neck strap, and attaches directly to the noseband. It limits head elevation through a fixed physical connection — when the horse raises his head beyond the length of the strap, the noseband is pulled downward and the horse feels resistance at his nose. It does not move with the horse's head; it simply establishes a ceiling above which the head cannot travel. It must be correctly adjusted — long enough that it does not restrict the horse's natural head carriage at rest, short enough that it engages when the head goes genuinely above the appropriate range. The running martingale divides into two branches that each end in a ring, and the reins pass through those rings rather than attaching directly to any part of the horse's head. When the horse raises his head and the reins angle upward beyond the point where the martingale rings engage, the running martingale changes the angle of the rein pressure — redirecting it downward through the martingale ring and asking the horse to lower his head to find the release. The running martingale is more forgiving than the standing martingale because it works with the rein rather than independently of it. Neither martingale is a substitute for correct training. Both are management tools that limit a specific problematic behavior in the moment without developing the horse's self-carriage or acceptance of the bit that correct training produces. A horse worked exclusively in a martingale without addressing the training reasons for the high head carriage will return to that carriage the moment the martingale is removed. Used correctly as a temporary tool while training work addresses the underlying cause, both types serve a legitimate purpose in specific situations.