Dressage experts can select horses for performance by observing a foal’s gaits at walk, trot, and canter. But choosing prospects for jumping demands a different way of judging the equine athlete, and now two research teams are trying to develop scientific methods that can analyze jumping ability.

Two university professors presented the results of their recent studies at the World Breeding Federation for Sport Horses Seminar last winter in Guadalajara, Mex-ico. Dr. René ¶an Weeren and Prof. Nathalie Crevier-De-noix, who conducted their studies in the Netherlands and France, each used computer-generated models of jumpers that calculated data to predict performance.

In the Netherlands, the question was how to predict a foal’s future career prospects by the way it jumps at 6 months of age. In France, researchers aimed to determine how body measurements indicated jumping success.

These studies go beyond the visual observation of a “cute” or “flashy” jumping style, to measure traits shared by efficient jumpers. Both are looking to define the characteristics of horses that clear obstacles consistently.

The research can benefit breeders, trainers and riders, all of whom would like to know which inborn traits make a horse a good jumper under saddle. But, at least so far, these studies have only given breeders and trainers some new tools with which to look at young horses.

Their methods and results may help breeders make decisions based on objective data, although so far the research has been carried out on a limited number of horses. Still, Crevier-Denoix is hoping to develop “a scientific basis for rational selection programs.”

Foals Over Fences

Van Weeren is an associate professor of veterinary medicine at Utrecht University in the Netherlands. His study featured a group of 40 foals, divided into an experimental group of 20 and a control group of 20. Each group was filmed free-jumping at ages 6 months, 4 years and 5 years.

The experimental group of foals were “trained” five days a week: three days’ exercise on a horse walker and two days’ free-jumping in a jumping lane with two obstacles: a crossrail, and at 5 to 6 meters (16′ to 19′) later, a rail set at .6 meters (2′).

University researchers conducted kinematic analysis of the horses’ jumping technique. (Kinematics is the study of gait patterns, or the cycle of a stride.) A series of six cameras recorded each of the 40 foals of the two groups cantering through the lane.

The research team aimed to quantify the technique through producing a computerized model, defined from 14 parameters they captured and analyzed. The phases of the jump determined the parameters to quantify–across the take-off, flight, and landing.

In each phase, van Weeren explained, “You look at the kinematics of the center of gravity. In the jump, there’s nothing very different from a cannonball in flight.”

The parameters, or variables to measure, included (with van Weeren’s comments in quotes):

Take-off phase: Two parameters: Velocity. Height and distance of the center of gravity with respect to the obstacle.

Flight phase: 12 parameters: Height and distance of center of gravity over the obstacle. Distance of front fetlock to the obstacle (“A very important parameter”). Joint angles in the front limbs. Length of the front limbs (“Measured from fetlock to shoulder”). Height and distance of the center of gravity to the obstacle, or the bascule (“Center of gravity is at its maximum height”). In hind limbs over the top rail, the distance of the fetlock to the obstacle. The joint angle of the hind limbs. The length of the hind limbs, or the measurement from fetlock to hip. The angle of hind limbs compared with the horizontal (ground).
The inclination of the back, or as the horse begins its descent, the angle of the back compared with the horizontal. The retroflexion angle of hind limbs (“The degree to which the horse kicks out with the hind limbs”). The total distance covered and the duration of the jump.

Researchers placed 25 reflective markers on the horses to record data for computer analysis. They filmed horses again at 4 years, in a series of three fences: a rail .4 meters high (16″), then at 7 meters (23′) a rail .6 meters high (2′), and at 6.4 meters (19′), a rail set at 1.10 meters (3’7″).

The third filming of horses, at 5 years, used the same three fences, with the final rail set at 1.2 meters (3’11”).

All the 5-year-olds went through a year of jumping training under saddle. They were filmed both free-jumping and under saddle through the jumping lane.

With the foals recorded, van Weeren said, “Then we tried to answer our question: Can we predict performance? The analysis of the experimental group was to see if training helps the foal.”

The answer was “yes.”

Said van Weeren, “In the take-off, the trained horses had less velocity, more elbow flexion, and decreased forelimb length. In flight, their center of gravity was lower.”

He added, “Observing the foal might tell you something about its future performance–its potential value as a show jumper.”

The trained foals were able to clear fences with lower body heights, without overjumping. They used themselves more efficiently in the hindquarters, for a jump of less duration and length.

Researchers also documented fewer refusals and knockdowns in the trained foals.

The same group maintained superior ability as 4-year-olds. “The experimental horses were more efficient and showed less effort,” reported van Weeren. “They needed less energy to clear the obstacles.”

But at age 5, the control group matched the experimental group in jumping. “There were no significant differences in technique or faults and refusals,” van Weeren summarized. “The variation in jumping technique levels out after a year of training.”

He did add, though, “At 5 years the best jumpers showed significantly more forelimb flexion and hind limb retroflexion than the worst jumpers–both at 6 months and 5 years.”

He also pointed out that the horse’s power over fences could compensate for faulty technique. “And character is very important. Look at the horse’s personality traits,” he said.

Van Weeren agreed that the rider’s influence could have affected the 5-year-olds’ jumping. “But the rider can’t make a really bad jumper into a good one,” he said.

Measuring Jumpers’ Structure In 3-D

From France’s National Veterinary School in Alfort, Crevier-Denoix presented “A 3-D Video Morphometric Measurement Method.” (Morphometric is the measuring of structure.) This study focused on how jumpers inherit the conformation that’s related to superior performance.

“The study is to calculate heritability,” said Crevier-Denoix.

Typically, horsemen evaluate jumpers’ conformation through observation, a subjective opinion. Crevier-Denoix commented on scientific methods such as (1) objective measurements of height, width and circumference of the limbs; or (2) photographs of reference-point markers glued to the horse. But method 1 may not indicate data relevant to performance, and method 2 takes time and requires each horse to stand squarely.

“A breeding program needs objective, precise measurement on large numbers, such as young horses in the field,” explained Crevier-Denoix. Therefore, she used a video method similar to van Weeren’s, “derived from kinematic analysis to record the horse while walking. It uses natural and spontaneous reference positions.”

Computerized video techniques form a model, producing three-dimensional data from real-life distances and angles of the horse’s body in motion.

Researchers measure anatomical landmarks of the horse’s skeletal structure, filmed for later analysis. “3-D gives you real length and angles,” said Crevier-Denoix.

Working with the Haras Nationaux (French National Stud) and Selle Franç¡©s breeders, Crevier-Denoix and her team recorded horses in the field. In their initial study, they chose 40 jumpers already showing in France.

They marked a path for each horse to walk, with four digital video cameras to record the gait. Each horse was led down the path, turned, and walked back.

“We recorded a calibration structure,” said Crevier-Denoix. In the structure formed from the four video images, they tracked positions of landmarks related to the horse’s offside legs.

She explained, “The reference position was the vertical image of the right fore and right hind at the walk. We selected 15 bony landmarks for the forelimb and 13 on the hind limb.”

Landmarks included tracking the withers, croup, and hip angle on both the fore and hind legs.

This study was able to record many horses in a short time (2 minutes each), at the owners’ convenience. Horses simply walked the path while cameras recorded the gait.

“The recording time is very short, and so it was accepted by owners and riders,” said Crevier-Denoix. “It could be done at a show.”

They chose the walk because it’s a uniform gait. “There is less variability at the walk, compared to the horse standing square. Also, it’s easier with foals,” said Crevier-Denoix.

The video produced morphometric (structure-measuring) data for computer software to calculate the height and length of body segments. In the laboratory, software projected angles between segments in the structure and produced the three-dimensional image. Researchers could view a horse’s skeletal planes–both straight on and lengthwise.

The first study compared two groups of 20 Selle Franç¡©s jumpers. Group A had a high sport index, greater than 150; group B had a low index of 101. Researchers found that the group A jumpers were higher in the hindquarters by 2 to 3 centimeters. They had longer croups, longer thighs (femur bones), and longer cannon bones. They were also shorter in length of the trunk (the measurement from shoulder to hip).

So are jumpers built “downhill”? Crevier-Denoix said no, clarifying, “The motor is in the hindquarters for speed and propulsion.”

She also noted that breeders like short cannon bones, but the study showed that the better jumpers had longer cannons. “It reduces inertia in jumping. It facilitates elbow flexion. The horse actively flexes the elbow and jumps more efficiently,” she said.

In their angles, the group A horses had a smaller angle (less steep) from croup to withers. The angle of the hind pastern was straighter, and the angle of forearm to shoulder was less.

“The longer croup and thigh are well-known in race horses,” said Crevier-Denoix. “Longer proximal bones and muscles are more efficient in both propulsion and engagement.”

She added, “We need to study a larger population to validate the data. In the literature, there is little data to compare conformation with performance, but this method can reveal significant differences.”

The French are now expanding this study to young horses (750 Selle Franç¡©s aged 4 and 5 years) and keeping records of 130 foals. Crevier-Denoix described the foal study:

“The foals were measured at 6 months, then filmed at 18 months, and next year at 3 years of age. We will study the evolution of conformation, especially the limbs–to judge the 6-month-old conformation as a prediction of the 3-year-old.”