Stirrup Placement and Rider Biomechanics: What's the Link?
Where do you place your stirrups? We know stirrup length affects your position, forces, and contact with your horse. But recent study results suggest that horizontal stirrup placement does, as well. By adjusting the site where you attach your stirrup leathers to your saddle, you could change the way you ride—for better or for worse.

Equipping saddles with adjustable stirrup bars, bringing the leathers farther forward or father backward on the saddle, can help customize the ride for each horse-rider pair, said Pauline Martin, DVM, PhD, of the University of Lyon, the National Veterinary School of Maisons-Alfort, and CWD France-Sellerie saddlery, in Nontron.

Martin and fellow researcher Marie Sapone, MSc, studied the biomechanical effects on two riders using a saddle with adjustable stirrup bars. Each rider rode the same horse at a canter with the stirrups set to three different positions: forward, central, and back. They presented their results, part of their larger Saddle in Motion Project, at the 2017 French Equine Research Day, held earlier this year in Paris.

They found that each rider’s biomechanics changed dramatically from one position to another, Martin said, and those biomechanics also differed considerably between the riders.

“The first rider was small and had a very high level as an experienced equestrian, and the second rider was taller and had an intermediate level of riding,” Martin said. “Their size differences and especially the differences in their experience are certainly affecting their biomechanics.”

For example, the higher-level rider tended to lean more forward when the stirrups were adjusted farther back, and sit straighter when the stirrups were adjusted more in front. Likewise, her forces on the horse’s back were greater under the front part of the saddle when the stirrups were back and under the back part of the saddle when the stirrups were in front, Martin said.

“She also indicated that she preferred having the stirrups in the most forward position,” she said.

The intermediate-level rider showed little change in her posture, which remained fairly stiff throughout the experiment, regardless of the stirrup position, the researchers said. But the forward (stirrup) position caused her to have equal pressures across the horse’s back. “This rider indicated that the forward position made her feel like she was being thrown backward,” Martin said.

Rider biomechanics can significantly influence their horses’ biomechanics, affecting performance, musculoskeletal health, and welfare, she said. These study results suggest that offering an adjustable stirrup bar that changes the leathers’ horizontal position can provide a more customized seat and ride for rider-horse pairs of all levels.

“The horizontal placement of the stirrups may be as important as their vertical placement,” Martin said.

Even so, it’s possible that teaching the intermediate-level rider to adjust her position might have more importance than adjusting the stirrups’ position, Martin added.

Studies on how these changing rider biomechanics affect the horse’s biomechanics are forthcoming, the researchers stated.