Effects of saddle tilt and stirrup length on the kinetics of horseback riders

BACKGROUND: How the modification of saddle fitting parameters in horse riding affects rider’s kinetics is very uncertain. The aim of this study is to describe how manipulating the two main adjustments that an end-user is likely to perform (saddle tilt and stirrup length) affects the biomechanics of a horse rider on a living horse. METHODS: Eleven showjumpers volunteered to take part in this study. Each participant performed a 120-strides standardization trial at trot and canter, with 0° saddle tilt and stirrup length that would position the rider’s knee at 90°. Following the standardization trial, four interventions were performed, which consisted of 60 strides with 60 mm shorter stirrups, 60 mm longer stirrups, 4° forward tilted saddle and 4° backward tilted saddle. Stirrup and rein tension forces were measured with tension loadcells. A symmetry index was calculated. Acceleration was measured with inertial measuring units at the helmet and back of the rider and shock attenuation was calculated. RESULTS: Shortening the stirrups and adjusting saddle tilt significantly enhanced shock attenuation at canter and increased force on the stirrups at trot and canter (p < 0.05). Lowering the stirrups reduced rein tension forces (p = 0.01). At trot, adjusting saddle tilt and stirrup length enhanced symmetry index on the bit (p < 0.05). These results allowed for general guidelines to be proposed, although individualization became an evident part of any saddle setup design due to a high inter-subject variability.