Quantification of the Effect of Saddle Fitting on Rider-Horse Biomechanics Using Inertial Measurement Units

The saddle's adaptability to the rider-horse pair's biomechanics is essential for equestrian comfort and performance. However, approaches to dynamic evaluation of saddle fitting are still limited in equestrian conditions. The purpose of this study is to propose a method of quantifying saddle adaptation to the rider-horse pair in motion. Eight rider-horse pairs were tested using four similar saddles with small modifications (seat depth, flap width, and front panel thickness). Seven inertial sensors were attached to the riders and horses to measure the active range of motion of the horses' forelimbs and hindlimbs, stride duration, active range of motion of the rider's pelvis, and rider-horse interaction. The results reveal that even small saddle changes affect the pair's biomechanics. Some saddle configurations limit the limbs' active range of motion, lengthen strides, or modify the rider's pelvic motion. The temporal offset between the movements of the horse and the rider changes depending on the saddle modifications. These findings support the effect of fine saddle changes on the locomotion and synchronization of the rider-horse pair. The use of inertial sensors can be a potential way for quantifying the influence of dynamic saddle fitting and optimizing saddle adaptability in stable conditions with saddle fitter constraints.