The saddle mat is a new measuring device to evaluate the pressure distribution under a saddle. With this mat it is possible to check the fit of the saddle. The aim of this study is to find and describe the relation between the calculated force progression and the movement of the horse in order to create a data base with reference data for further studies. The determination of the movement of the centre of pressure and the comparison of the movement of the horse's back with and without rider were additional goals of this study. We measured 12 horses with their used saddles which were ridden by their normal riders. The backs of the horses were clinically evaluated for abnormalities and the fit of the saddles were checked. All the riders were able to ride their horses in a correct way. Simultaneously combined recordings were taken with the saddle mat and the kinematic measuring system. The measurements were taken at walk, trot and canter with the rider and at walk and trot without the rider mounted on the horse. The data allow an accurate association of the overall force, the forces in the four parts (fore left, fore right, hind left, hind right) and the movement of the centre of pressure with the movement in the different gaits. The graphs show a standard pattern, which indicates that it is possible to compare different groups as long as they fulfil certain standards like all riders sitting in a correct way. The comparison of the movement of the horses back with and without rider showed very clearly that especially in the withers region the presence of a rider constricts the movement of the back. The results show that it is very important to have a saddle which fits correctly, because if the saddle doesn't fit the restriction of the movement increases and lasting damage of the spine and the muscles of the back can occur.