The speed corresponds to the time necessary to cover a certain distance.
However, it is not a notion specific to the practice of horse-riding. Indeed, it is found in many fields such as automobile racing or running for example. Even though the universal computing unit of speed is either mph or m/s, for equestrian sports the speed is given in m/min.
Computing the speed is easy. You simply divide the distance you covered by the time it took you to cover it.
The speed notion is essential in several disciplines in equestrian sports. During a jumping course, it is the speed which will help you to improve your time compared to your competitors, thus enabling you to claim victory.
The reference speed in competition varies from 250 m/min to 400m/min depending on the classes and levels, according the federation norms.