Rider study highlights effects of saddle and stirrup adjustments

The effects of stirrup length and saddle tilt have been highlighted in a recent study, with a significant influence found on rider kinetics.

Marc Elmeua González and Nejc Šarabon, writing in the journal PeerJ, noted that lower back pain is the most common chronic injury experienced by horse riders, linked to poor postural control and pelvic alignment.

“Despite this, adjusting saddles to fit riders has not been a priority in the scientific literature of showjumping equestrianism,” they said. “Instead, authors have focused on how manipulating saddles to fit their horses can influence the animal’s performance and top line health.”

The pair, with the University of Primorska in Slovenia, set out to describe how manipulating two main adjustments that an end-user is likely to perform – saddle tilt and stirrup length – affects the biomechanics of a horse rider.

Eleven showjumpers volunteered to take part in the study. Each performed a 120-stride standardization trial at trot and canter, with 0 degrees of saddle tilt and a stirrup length that positioned each rider’s knees at 90 degrees.

Following this, four interventions were performed, which consisted of 60 strides with 60mm shorter stirrups, 60mm longer stirrups, a 4-degree forward-tilted saddle, and a 4-degree backward-tilted saddle.

Stirrup and rein tension forces were measured with tension loadcells.

Symmetry was investigated and indexed. Acceleration was measured with inertial measuring units at the helmet and back of the rider, and shock attenuation was calculated.

González and Šarabon said they had expected singular and distinct responses from each rider, while depicting common trends.

“Shortening the stirrups enhanced shock attenuation while riding at canter, and increased the force applied at the stirrups both at trot and canter. Longer stirrups lead to lighter stirrup forces.”

These results agree with previous findings that peak forces underneath the saddle decrease with higher stirrup forces.

Adjusting saddle tilt either forward or backward resulted in an improved shock attenuation at the canter, suggesting that small (less than 4 degree) tilts can significantly reduce the impact on the rider’s back. Indeed, 65% of the subjects responded positively to such saddle modifications.

At the trot, adjusting the saddle tilt and stirrup length surprisingly decreased the amount of uneven pressure applied to the bit.

The authors said their results allow for general guidelines to be proposed, although individualization became an evident part of any saddle setup design due to high variability between the subjects.

“In any athletic discipline, it is hard to postulate absolutes in terms of correct techniques, equipment setups, etc. In equestrian sports it is even harder, as a living animal that we barely understand comes into the game as the main character.”

They said their findings can serve as a base to modify specific parameters of the saddle setup according to the needs of each rider.

“While some conclusions can be drawn, at this stage it would be premature to claim a correct way of adjusting saddle parameters to fit a rider.

“It is undeniable however, that the importance of individualization is paramount, and that adjusting a saddle to fit a rider has a potential impact on the rider’s back health and should not be neglected.

“Moreover, our data suggest that elongating stirrups shifts the weight from stirrup to saddle and shortening does the opposite action.

“While no length is better than another, it is useful to know the direction of change to properly apply it during training and competition in a show-jumping setting.”

Elmeua González M, Šarabon N. 2022. Effects of saddle tilt and stirrup length on the kinetics of horseback riders.
PeerJ 10:e14438 http://doi.org/10.7717/peerj.14438

The study, published under a Creative Commons License, can be read here.