REASONS FOR PERFORMING STUDY: To a large extent the success of a racehorse depends on effective and health preserving training methods. An important issue is the prevention of back pain. The influence of different types of training saddles (normal tree: S(A), treeless: S(B), flexible tree: S(C)) on the saddle pressure patterns in racehorses have not previously been investigated. It is commonly assumed that S(A) limits the motion of the back especially in the lower thoracic region during gallop. Hypothesis: S(A) produces higher pressures in the caudal part of the saddle at trot (rising trot), canter and gallop (both in a jockey seat) compared to S(B) and S(C). METHODS: Saddle pressures were measured in 8 racehorses ridden on a training track at trot (3.5 m/s), canter (6.4 m/s) and gallop (12.6 m/s). Each horse performed the protocol with each saddle. To analyse the pressure distribution over the horse's back the pressure picture was divided into thirds (TD(front), TD(mid), TD(hind)). The stride-mean loaded areas, forces and mean and peak pressures were determined. RESULTS: At canter and gallop, all 3 saddles were mainly loaded in TD(front) (>80% of the rider's weight), with a decreasing gradient to TD(mid) and TD(hind) (<3%), which was least pronounced in S(C). At trot, the load was shifted towards TD(mid) and TD(hind) (10-15%, each). High peak pressures occurred in TD(front) at canter and gallop and in TD(hind) at trot. CONCLUSIONS: The type of tree had no influence on the pressure picture of the caudal third at gallop. The high peak pressures observed in TD(hind) at trot in all saddles may limit the activity of the horse's back, which is of particular importance since trot is an integral part of the daily work.