EXTERNAL LOADS ON THE LIMBS OF JUMPING HORSES AT TAKE-OFF AND LANDING

Using a force plate, ground reaction force (GRF) patterns at take-off and landing between the hooves and the ground were recorded for all li mbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the righ t-leading canter. Distribution of the GRF and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory GRF of the hind limbs were 3 to 5 times higher than at the normal canter, depend ing on the jumping technique of the horse. At landing, the propulsory GRF were mainly increased in the trailing forelimb and in both hind li mbs. The vertical GRF amplitudes and force impulses were of similar ma gnitude to those at the canter, although increases up to 160% were fou nd in the hind limbs of the horse with the worst jumping technique. Th e trailing forelimb carried the highest loads, up to twice the animal' s body weight; GRF amplitudes tended to increase when higher fences we re used. However, the jumping technique of the horse may have more inf luence, because an easily jumping horse could clear a 1.3-m-high fence with similar loads on the limbs.