Coordination variability reveals the features of the 'independent seat' in competitive dressage riders.

The rider's ability to consistently coordinate their movements to their horse is a key determinant of performance in equestrian sport. This study investigated the inter-segmental coordination variability between the vertical displacement of a riding simulator and the pitch rotation of 28 competitive female dressage riders' head, trunk, pelvis, and left foot, in simulated medium and extended trot. A statistical non-parametric mapping three-way repeated-measures ANOVA investigated the influence of gait, competition level and segment on coordination variability. There was a significant main effect of gait and segment (p = 0.05), however, no significant effect of competition level. In medium trot, simulator-pelvis coupling was significantly (p < 0.001) less variable than simulator-head, -trunk, and -foot couplings. Significantly greater coordination variability of simulator-head and -foot relative to the trunk and pelvis suggested that riders can maintain stability in the saddle with their trunk and pelvis while allowing greater variability of their head and foot coupling to the simulator's vertical displacement. It is proposed that stronger coupling of the rider's pelvis relative to their other segments is one facet of the equestrian dressage skill of the independent seat. However, greater perturbations during simulated extended trot may necessitate a decrease in the independence of the rider's seat.