What is throughness in dressage and how do you achieve it?

Throughness — the German Durchlässigkeit, sometimes translated as permeability or throughness — describes the unobstructed flow of energy from the horse's hindquarters through a supple, swinging back, over the topline, and into a soft, elastic contact with the rider's hand, combined with the equally unobstructed transmission of the rider's aids from the hand, through the horse's body, to the hindquarters. A horse that is truly through is a horse through which energy flows in both directions without blockage — the hindquarter impulse reaches the contact, and the rein influence reaches the hindquarters — creating the sensation of riding a connected, responsive whole rather than a collection of parts that communicate imperfectly. Throughness is considered one of the most important qualities in dressage because it is the physical expression of the entire Training Scale working correctly: a horse can only be genuinely through if it has rhythm, suppleness, contact, impulsion, and straightness all functioning together, which is why experienced judges can read the quality of the training in the horse's throughness even before analyzing specific movements. Achieving throughness requires first establishing genuine forward energy from the hindquarters — not speed but active, elastic thrust — and then allowing that energy to flow through a relaxed, swinging back and into a soft, receiving contact rather than being blocked by tension anywhere along the chain. The primary causes of loss of throughness are tension in the horse's back — which blocks the forward flow of energy — and resistance or heaviness in the contact — which prevents the rider's influences from reaching the hindquarters. Every gymnastic exercise in dressage training ultimately serves the goal of developing or restoring throughness, which is why a horse that is genuinely through feels qualitatively different to ride than one that merely goes forward.