There are various ways of expressing movement which go beyond the photographically correct depiction of a scene.
Paintings and drawings are by nature still objects, so, if action is depicted, the artist has to convince the viewer that movement is actually happening.
The great master Auguste Rodin once defined movement as the "transition from one attitude to another". He advocated what he called "progressive development of movement" , meaning that he liked to depict successive phases of an action in the same sculpture, condensing the action of several moments into a single figure.
For me, distortion is a good way of expressing movement.
In my example of the horse jumping over the hurdle, the head of the horse has already cleared the obstacle, moving away from us, the hind legs, however, are just about to move into our field of vision and their muscles are in the moment of greatest activity. I made the exaggeration in size intuitively but I like the result, as it helps to create the illusion of movement.