An assembly for training and/or instruction of horses, for maintaining, building-up and improving the muscles and stance and posture of the horse by making the animal to walk or trot in the correct positions and stances, with the assembly comprising a girth fixed to the breast portion of the animal's body, the girth having a plurality of connecting points to which a rear cord and side cords are connected, with both cords connected to a rear tensor, wherein the cords and the tensor forces the animal to adopt a desired stance during the training thereof.