The lunger is one of the three scored elements in competitive vaulting and is arguably the most technically demanding role on the team. The lunger controls the horse from the center of the 15-meter circle using a lunge line and whip, maintaining the consistent rhythm, tempo, and shape of the circle that the vaulters depend on for every skill they perform.
At the competitive level the lunger must keep the horse in a correct, balanced canter that remains absolutely consistent regardless of what is happening on the horse's back — whether a single vaulter is performing a stand or a squad of eight vaulters is distributing weight unpredictably. Any irregularity in the canter that originates from the lunger's handling is reflected in the scores.
In training the lunger shapes every aspect of the horse's work. The relationship between the lunger and the horse is developed over years, and top vaulting horses typically work with the same lunger throughout their competition careers. A skilled lunger can correct problems in tempo before they affect the vaulter, calm a tense horse through quiet handling, and adjust the circle when surface conditions change.