Ground Reaction Forces of Dressage Horses Performing the Piaffe

SIMPLE SUMMARY: One of the most difficult movements performed by dressage horses is the piaffe, in which the horse raises and lowers alternating diagonal limb pairs while remaining in place. Piaffe is an artificial movement that requires good balance. Knowledge of the unique stresses on the horse’s limbs and body during the performance of the piaffe are needed to understand the mechanics of the movement and the implications for injury. In this study, we used force plates to measure ground reaction forces (GRFs) in the vertical, longitudinal and transverse directions in seven highly trained horses performing the piaffe. The results showed that the hindlimbs carried relatively more weight in the piaffe than in trot or passage, though the peak vertical GRF was significantly higher in the forelimbs. The forces acting in the horizontal plane showed considerable variability from step-to-step within individual horses. This was thought to represent the difficulty of maintaining balance when the horse stands on one diagonal pair of limbs. ABSTRACT: The piaffe is an artificial, diagonally coordinated movement performed in the highest levels of dressage competition. The ground reaction forces (GRFs) of horses performing the piaffe do not appear to have been reported. Therefore, the objective of this study was to describe three-dimensional GRFs in ridden dressage horses performing the piaffe. In-ground force plates were used to capture fore and hindlimb GRF data from seven well-trained dressage horses. Peak vertical GRF was significantly higher in forelimbs than in the hindlimbs (7.39 ± 0.99 N/kg vs. 6.41 ± 0.64 N/kg; p < 0.001) with vertical impulse showing a trend toward higher forelimb values. Peak longitudinal forces were small with no difference in the magnitude of braking or propulsive forces between fore and hindlimbs. Peak transverse forces were similar in magnitude to longitudinal forces and were mostly directed medially in the hindlimbs. Both the intra- and inter-individual variability of longitudinal and transverse GRFs were high (coefficient of variation 25–68%). Compared with the other diagonal gaits of dressage horses, the vertical GRF somewhat shifted toward the hindlimbs. The high step-to-step variability of the horizontal GRF components is thought to reflect the challenge of balancing on one diagonal pair of limbs with no forward momentum.