Running a horse in circles on a line is called longeing.
A rope, 20 to 30 feet long is attached to the horse’s bridle or halter while the handler stands in the middle of a circle. The horse then goes round and round the handler as part of training. The horse learns the voice commands to walk, trot and canter.
Although the handler holds a long whip in the other hand, it is not used to hit the horse. The whip is used to signal the horse to move forward. There are times when the sound of the crack of the whip is necessary to get the horse’s attention. But most times just the sight of the whip is enough to get the horse moving. The horse learns to respond to other voice commands as well.
Longeing helps horses that have an excess of energy work out before being ridden safely.